Unofficial FAQ: Ignition corrections
#31
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
r2000swler@hotmail.com wrote in
news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com:
> I now consider the igniter a subsystem that is doomed to failure. It
> simply operates too hot for prolonged life.
>
> Having said that, a friend's 1990 Civic has ~200K and is still on the
> original igniter.
My '91 Integra has 248K miles and the interior of the distributor is
entirely original, except for the rotor which I change every few years.
I wonder if maintenance might be a factor in igniter longevity the way it
is with coil longevity. Since the igniter is doing a lot of monitoring as
well as current carrying, might a large enough deviation from design spec
in ignition system characteristics overload the igniter?
--
TeGGeR®
The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/
news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com:
> I now consider the igniter a subsystem that is doomed to failure. It
> simply operates too hot for prolonged life.
>
> Having said that, a friend's 1990 Civic has ~200K and is still on the
> original igniter.
My '91 Integra has 248K miles and the interior of the distributor is
entirely original, except for the rotor which I change every few years.
I wonder if maintenance might be a factor in igniter longevity the way it
is with coil longevity. Since the igniter is doing a lot of monitoring as
well as current carrying, might a large enough deviation from design spec
in ignition system characteristics overload the igniter?
--
TeGGeR®
The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/
#32
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
"TeGGeR®" <tegger@tegger.c0m> wrote in
news:Xns96769CB008B15tegger@207.14.113.17:
> r2000swler@hotmail.com wrote in
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com:
>
>> I now consider the igniter a subsystem that is doomed to failure. It
>> simply operates too hot for prolonged life.
>>
>> Having said that, a friend's 1990 Civic has ~200K and is still on the
>> original igniter.
>
>
>
> My '91 Integra has 248K miles and the interior of the distributor is
> entirely original, except for the rotor which I change every few
> years.
>
>
> I wonder if maintenance might be a factor in igniter longevity the way
> it is with coil longevity. Since the igniter is doing a lot of
> monitoring as well as current carrying, might a large enough deviation
> from design spec in ignition system characteristics overload the
> igniter?
>
>
>
It might be related to spark plug wire condition,and spark plug
condition;if your wires are breaking down,it would place a greater load on
the coil,and if the plugs were gummed up,slagged,or carboned,that would
affect the coil voltage.
IMO,igniters fail because of transients and migration of metals in the
Darlington and IC.
One could conceivably use an electron microscope and examine failed igniter
semiconductors and see why they failed,but it would be an expensive
undertaking,unless you're a college student with access to an e-
microscope,and doing a thesis or paper.
--
Jim Yanik
jyanik
at
kua.net
news:Xns96769CB008B15tegger@207.14.113.17:
> r2000swler@hotmail.com wrote in
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com:
>
>> I now consider the igniter a subsystem that is doomed to failure. It
>> simply operates too hot for prolonged life.
>>
>> Having said that, a friend's 1990 Civic has ~200K and is still on the
>> original igniter.
>
>
>
> My '91 Integra has 248K miles and the interior of the distributor is
> entirely original, except for the rotor which I change every few
> years.
>
>
> I wonder if maintenance might be a factor in igniter longevity the way
> it is with coil longevity. Since the igniter is doing a lot of
> monitoring as well as current carrying, might a large enough deviation
> from design spec in ignition system characteristics overload the
> igniter?
>
>
>
It might be related to spark plug wire condition,and spark plug
condition;if your wires are breaking down,it would place a greater load on
the coil,and if the plugs were gummed up,slagged,or carboned,that would
affect the coil voltage.
IMO,igniters fail because of transients and migration of metals in the
Darlington and IC.
One could conceivably use an electron microscope and examine failed igniter
semiconductors and see why they failed,but it would be an expensive
undertaking,unless you're a college student with access to an e-
microscope,and doing a thesis or paper.
--
Jim Yanik
jyanik
at
kua.net
#33
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
"TeGGeR®" <tegger@tegger.c0m> wrote in
news:Xns96769CB008B15tegger@207.14.113.17:
> r2000swler@hotmail.com wrote in
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com:
>
>> I now consider the igniter a subsystem that is doomed to failure. It
>> simply operates too hot for prolonged life.
>>
>> Having said that, a friend's 1990 Civic has ~200K and is still on the
>> original igniter.
>
>
>
> My '91 Integra has 248K miles and the interior of the distributor is
> entirely original, except for the rotor which I change every few
> years.
>
>
> I wonder if maintenance might be a factor in igniter longevity the way
> it is with coil longevity. Since the igniter is doing a lot of
> monitoring as well as current carrying, might a large enough deviation
> from design spec in ignition system characteristics overload the
> igniter?
>
>
>
It might be related to spark plug wire condition,and spark plug
condition;if your wires are breaking down,it would place a greater load on
the coil,and if the plugs were gummed up,slagged,or carboned,that would
affect the coil voltage.
IMO,igniters fail because of transients and migration of metals in the
Darlington and IC.
One could conceivably use an electron microscope and examine failed igniter
semiconductors and see why they failed,but it would be an expensive
undertaking,unless you're a college student with access to an e-
microscope,and doing a thesis or paper.
--
Jim Yanik
jyanik
at
kua.net
news:Xns96769CB008B15tegger@207.14.113.17:
> r2000swler@hotmail.com wrote in
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com:
>
>> I now consider the igniter a subsystem that is doomed to failure. It
>> simply operates too hot for prolonged life.
>>
>> Having said that, a friend's 1990 Civic has ~200K and is still on the
>> original igniter.
>
>
>
> My '91 Integra has 248K miles and the interior of the distributor is
> entirely original, except for the rotor which I change every few
> years.
>
>
> I wonder if maintenance might be a factor in igniter longevity the way
> it is with coil longevity. Since the igniter is doing a lot of
> monitoring as well as current carrying, might a large enough deviation
> from design spec in ignition system characteristics overload the
> igniter?
>
>
>
It might be related to spark plug wire condition,and spark plug
condition;if your wires are breaking down,it would place a greater load on
the coil,and if the plugs were gummed up,slagged,or carboned,that would
affect the coil voltage.
IMO,igniters fail because of transients and migration of metals in the
Darlington and IC.
One could conceivably use an electron microscope and examine failed igniter
semiconductors and see why they failed,but it would be an expensive
undertaking,unless you're a college student with access to an e-
microscope,and doing a thesis or paper.
--
Jim Yanik
jyanik
at
kua.net
#34
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
r2000swler@hotmail.com wrote:
> Jim Yanik wrote (in part):
>
> Yes,coil current has to reach some preset point before the IC shuts off
> the
> Darlington. That's the job of that IC.
>
> The only way we will truly know for sure is to get a look at the IC's
> app
> sheet,or scope the ECU signal to the igniter and see if it's pulse
> width
> increases.If it does,then it controls the PW,not the IC.
>
> --
> Jim Yanik
> ---------------------------
>
> I have several "systems" pulled from cars to be crushed.
> I rigged a 1990 ECM and sensors, with igniter to try
> and figure out what was going on.
>
> I am after a simple way to monitor the on time of the FIs.
>
> I was kind of suprised to see the ignition pulse width
> incrase with engine speed. I used a dual channel oscilloscope
> and the output from the ECM stayed the same.
>
> I experimented using a HP pulse generator to drive the igniter
> by itself and found the same thing to be true. In my celica the PW
> is directly controled by the ECM. I am asuming the IC monitors the
> delta V, or rate of change and integrates the data to determine PW.
>
> I will try to test my 1991 Civc this weekend. I have brought most of
> the
> ECM outputs and inputs via 1K isolation resistors to a breakout box
> for testing.
that would be most excellent!
>
> I think it will be very usefull to measure on ratio of the FIs to
> squeeze
> every erg from the fuel for best MGP.
>
> I can say that in many ways the ECM doesn't work the way I thought.
> There are odd actions during the warm up period.
>
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
> Having said that, a friend's 1990 Civic has ~200K and is still on the
> original igniter. Somewhere I have a motorola "designing for long
> life of Si devices"(something like that) that says that for every 3
> degree
> rise in temp over 20C, the life will be cut in half. But based on that
> the
> ~90 degrees C engine temp the igniter ought to fail in the first 100
> miles.
> There are many things I just don't understand here.
>
> But I now carry a spare ECM and igniter "just in case".
>
> Terry
>
> Jim Yanik wrote (in part):
>
> Yes,coil current has to reach some preset point before the IC shuts off
> the
> Darlington. That's the job of that IC.
>
> The only way we will truly know for sure is to get a look at the IC's
> app
> sheet,or scope the ECU signal to the igniter and see if it's pulse
> width
> increases.If it does,then it controls the PW,not the IC.
>
> --
> Jim Yanik
> ---------------------------
>
> I have several "systems" pulled from cars to be crushed.
> I rigged a 1990 ECM and sensors, with igniter to try
> and figure out what was going on.
>
> I am after a simple way to monitor the on time of the FIs.
>
> I was kind of suprised to see the ignition pulse width
> incrase with engine speed. I used a dual channel oscilloscope
> and the output from the ECM stayed the same.
>
> I experimented using a HP pulse generator to drive the igniter
> by itself and found the same thing to be true. In my celica the PW
> is directly controled by the ECM. I am asuming the IC monitors the
> delta V, or rate of change and integrates the data to determine PW.
>
> I will try to test my 1991 Civc this weekend. I have brought most of
> the
> ECM outputs and inputs via 1K isolation resistors to a breakout box
> for testing.
that would be most excellent!
>
> I think it will be very usefull to measure on ratio of the FIs to
> squeeze
> every erg from the fuel for best MGP.
>
> I can say that in many ways the ECM doesn't work the way I thought.
> There are odd actions during the warm up period.
>
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
> Having said that, a friend's 1990 Civic has ~200K and is still on the
> original igniter. Somewhere I have a motorola "designing for long
> life of Si devices"(something like that) that says that for every 3
> degree
> rise in temp over 20C, the life will be cut in half. But based on that
> the
> ~90 degrees C engine temp the igniter ought to fail in the first 100
> miles.
> There are many things I just don't understand here.
>
> But I now carry a spare ECM and igniter "just in case".
>
> Terry
>
#35
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
r2000swler@hotmail.com wrote:
> Jim Yanik wrote (in part):
>
> Yes,coil current has to reach some preset point before the IC shuts off
> the
> Darlington. That's the job of that IC.
>
> The only way we will truly know for sure is to get a look at the IC's
> app
> sheet,or scope the ECU signal to the igniter and see if it's pulse
> width
> increases.If it does,then it controls the PW,not the IC.
>
> --
> Jim Yanik
> ---------------------------
>
> I have several "systems" pulled from cars to be crushed.
> I rigged a 1990 ECM and sensors, with igniter to try
> and figure out what was going on.
>
> I am after a simple way to monitor the on time of the FIs.
>
> I was kind of suprised to see the ignition pulse width
> incrase with engine speed. I used a dual channel oscilloscope
> and the output from the ECM stayed the same.
>
> I experimented using a HP pulse generator to drive the igniter
> by itself and found the same thing to be true. In my celica the PW
> is directly controled by the ECM. I am asuming the IC monitors the
> delta V, or rate of change and integrates the data to determine PW.
>
> I will try to test my 1991 Civc this weekend. I have brought most of
> the
> ECM outputs and inputs via 1K isolation resistors to a breakout box
> for testing.
that would be most excellent!
>
> I think it will be very usefull to measure on ratio of the FIs to
> squeeze
> every erg from the fuel for best MGP.
>
> I can say that in many ways the ECM doesn't work the way I thought.
> There are odd actions during the warm up period.
>
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
> Having said that, a friend's 1990 Civic has ~200K and is still on the
> original igniter. Somewhere I have a motorola "designing for long
> life of Si devices"(something like that) that says that for every 3
> degree
> rise in temp over 20C, the life will be cut in half. But based on that
> the
> ~90 degrees C engine temp the igniter ought to fail in the first 100
> miles.
> There are many things I just don't understand here.
>
> But I now carry a spare ECM and igniter "just in case".
>
> Terry
>
> Jim Yanik wrote (in part):
>
> Yes,coil current has to reach some preset point before the IC shuts off
> the
> Darlington. That's the job of that IC.
>
> The only way we will truly know for sure is to get a look at the IC's
> app
> sheet,or scope the ECU signal to the igniter and see if it's pulse
> width
> increases.If it does,then it controls the PW,not the IC.
>
> --
> Jim Yanik
> ---------------------------
>
> I have several "systems" pulled from cars to be crushed.
> I rigged a 1990 ECM and sensors, with igniter to try
> and figure out what was going on.
>
> I am after a simple way to monitor the on time of the FIs.
>
> I was kind of suprised to see the ignition pulse width
> incrase with engine speed. I used a dual channel oscilloscope
> and the output from the ECM stayed the same.
>
> I experimented using a HP pulse generator to drive the igniter
> by itself and found the same thing to be true. In my celica the PW
> is directly controled by the ECM. I am asuming the IC monitors the
> delta V, or rate of change and integrates the data to determine PW.
>
> I will try to test my 1991 Civc this weekend. I have brought most of
> the
> ECM outputs and inputs via 1K isolation resistors to a breakout box
> for testing.
that would be most excellent!
>
> I think it will be very usefull to measure on ratio of the FIs to
> squeeze
> every erg from the fuel for best MGP.
>
> I can say that in many ways the ECM doesn't work the way I thought.
> There are odd actions during the warm up period.
>
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
> Having said that, a friend's 1990 Civic has ~200K and is still on the
> original igniter. Somewhere I have a motorola "designing for long
> life of Si devices"(something like that) that says that for every 3
> degree
> rise in temp over 20C, the life will be cut in half. But based on that
> the
> ~90 degrees C engine temp the igniter ought to fail in the first 100
> miles.
> There are many things I just don't understand here.
>
> But I now carry a spare ECM and igniter "just in case".
>
> Terry
>
#36
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
Jim Yanik wrote:
> "TeGGeR®" <tegger@tegger.c0m> wrote in
> news:Xns96769CB008B15tegger@207.14.113.17:
>
>
>>r2000swler@hotmail.com wrote in
>>news:1118859696.926058.152280@z14g2000cwz.google groups.com:
>>
>>
>>>I now consider the igniter a subsystem that is doomed to failure. It
>>>simply operates too hot for prolonged life.
>>>
>>>Having said that, a friend's 1990 Civic has ~200K and is still on the
>>>original igniter.
>>
>>
>>
>>My '91 Integra has 248K miles and the interior of the distributor is
>>entirely original, except for the rotor which I change every few
>>years.
>>
>>
>>I wonder if maintenance might be a factor in igniter longevity the way
>>it is with coil longevity. Since the igniter is doing a lot of
>>monitoring as well as current carrying, might a large enough deviation
>>from design spec in ignition system characteristics overload the
>>igniter?
>>
>>
>>
>
>
> It might be related to spark plug wire condition,and spark plug
> condition;if your wires are breaking down,it would place a greater load on
> the coil,and if the plugs were gummed up,slagged,or carboned,that would
> affect the coil voltage.
> IMO,igniters fail because of transients and migration of metals in the
> Darlington and IC.
there are two "migration" mechanisms - first is solid state diffusion.
that's where the bit about the life halving every 3 degrees comes in.
the other is a mass transportation effect at high current densities.
unfortunately, high current leads to heat, and semi conductors have high
current densities, so the only real way to know for sure about the
failure mechanism, as you say, is microscopy.
>
> One could conceivably use an electron microscope and examine failed igniter
> semiconductors and see why they failed,but it would be an expensive
> undertaking,unless you're a college student with access to an e-
> microscope,and doing a thesis or paper.
>
of the two igniter types tegger shows, the second is designed more for a
high temperature environment from what i can see. the small scale
circuitry in the components of the first igniter have much smaller
diffusion paths. the larger scale thick film device has, for
semiconductors at any rate, truly massive scale features. these are bad
for speed, but even at 10,000 rpm, that's only 166Hz, not exactly a high
frequency challenge.
> "TeGGeR®" <tegger@tegger.c0m> wrote in
> news:Xns96769CB008B15tegger@207.14.113.17:
>
>
>>r2000swler@hotmail.com wrote in
>>news:1118859696.926058.152280@z14g2000cwz.google groups.com:
>>
>>
>>>I now consider the igniter a subsystem that is doomed to failure. It
>>>simply operates too hot for prolonged life.
>>>
>>>Having said that, a friend's 1990 Civic has ~200K and is still on the
>>>original igniter.
>>
>>
>>
>>My '91 Integra has 248K miles and the interior of the distributor is
>>entirely original, except for the rotor which I change every few
>>years.
>>
>>
>>I wonder if maintenance might be a factor in igniter longevity the way
>>it is with coil longevity. Since the igniter is doing a lot of
>>monitoring as well as current carrying, might a large enough deviation
>>from design spec in ignition system characteristics overload the
>>igniter?
>>
>>
>>
>
>
> It might be related to spark plug wire condition,and spark plug
> condition;if your wires are breaking down,it would place a greater load on
> the coil,and if the plugs were gummed up,slagged,or carboned,that would
> affect the coil voltage.
> IMO,igniters fail because of transients and migration of metals in the
> Darlington and IC.
there are two "migration" mechanisms - first is solid state diffusion.
that's where the bit about the life halving every 3 degrees comes in.
the other is a mass transportation effect at high current densities.
unfortunately, high current leads to heat, and semi conductors have high
current densities, so the only real way to know for sure about the
failure mechanism, as you say, is microscopy.
>
> One could conceivably use an electron microscope and examine failed igniter
> semiconductors and see why they failed,but it would be an expensive
> undertaking,unless you're a college student with access to an e-
> microscope,and doing a thesis or paper.
>
of the two igniter types tegger shows, the second is designed more for a
high temperature environment from what i can see. the small scale
circuitry in the components of the first igniter have much smaller
diffusion paths. the larger scale thick film device has, for
semiconductors at any rate, truly massive scale features. these are bad
for speed, but even at 10,000 rpm, that's only 166Hz, not exactly a high
frequency challenge.
#37
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
Jim Yanik wrote:
> "TeGGeR®" <tegger@tegger.c0m> wrote in
> news:Xns96769CB008B15tegger@207.14.113.17:
>
>
>>r2000swler@hotmail.com wrote in
>>news:1118859696.926058.152280@z14g2000cwz.google groups.com:
>>
>>
>>>I now consider the igniter a subsystem that is doomed to failure. It
>>>simply operates too hot for prolonged life.
>>>
>>>Having said that, a friend's 1990 Civic has ~200K and is still on the
>>>original igniter.
>>
>>
>>
>>My '91 Integra has 248K miles and the interior of the distributor is
>>entirely original, except for the rotor which I change every few
>>years.
>>
>>
>>I wonder if maintenance might be a factor in igniter longevity the way
>>it is with coil longevity. Since the igniter is doing a lot of
>>monitoring as well as current carrying, might a large enough deviation
>>from design spec in ignition system characteristics overload the
>>igniter?
>>
>>
>>
>
>
> It might be related to spark plug wire condition,and spark plug
> condition;if your wires are breaking down,it would place a greater load on
> the coil,and if the plugs were gummed up,slagged,or carboned,that would
> affect the coil voltage.
> IMO,igniters fail because of transients and migration of metals in the
> Darlington and IC.
there are two "migration" mechanisms - first is solid state diffusion.
that's where the bit about the life halving every 3 degrees comes in.
the other is a mass transportation effect at high current densities.
unfortunately, high current leads to heat, and semi conductors have high
current densities, so the only real way to know for sure about the
failure mechanism, as you say, is microscopy.
>
> One could conceivably use an electron microscope and examine failed igniter
> semiconductors and see why they failed,but it would be an expensive
> undertaking,unless you're a college student with access to an e-
> microscope,and doing a thesis or paper.
>
of the two igniter types tegger shows, the second is designed more for a
high temperature environment from what i can see. the small scale
circuitry in the components of the first igniter have much smaller
diffusion paths. the larger scale thick film device has, for
semiconductors at any rate, truly massive scale features. these are bad
for speed, but even at 10,000 rpm, that's only 166Hz, not exactly a high
frequency challenge.
> "TeGGeR®" <tegger@tegger.c0m> wrote in
> news:Xns96769CB008B15tegger@207.14.113.17:
>
>
>>r2000swler@hotmail.com wrote in
>>news:1118859696.926058.152280@z14g2000cwz.google groups.com:
>>
>>
>>>I now consider the igniter a subsystem that is doomed to failure. It
>>>simply operates too hot for prolonged life.
>>>
>>>Having said that, a friend's 1990 Civic has ~200K and is still on the
>>>original igniter.
>>
>>
>>
>>My '91 Integra has 248K miles and the interior of the distributor is
>>entirely original, except for the rotor which I change every few
>>years.
>>
>>
>>I wonder if maintenance might be a factor in igniter longevity the way
>>it is with coil longevity. Since the igniter is doing a lot of
>>monitoring as well as current carrying, might a large enough deviation
>>from design spec in ignition system characteristics overload the
>>igniter?
>>
>>
>>
>
>
> It might be related to spark plug wire condition,and spark plug
> condition;if your wires are breaking down,it would place a greater load on
> the coil,and if the plugs were gummed up,slagged,or carboned,that would
> affect the coil voltage.
> IMO,igniters fail because of transients and migration of metals in the
> Darlington and IC.
there are two "migration" mechanisms - first is solid state diffusion.
that's where the bit about the life halving every 3 degrees comes in.
the other is a mass transportation effect at high current densities.
unfortunately, high current leads to heat, and semi conductors have high
current densities, so the only real way to know for sure about the
failure mechanism, as you say, is microscopy.
>
> One could conceivably use an electron microscope and examine failed igniter
> semiconductors and see why they failed,but it would be an expensive
> undertaking,unless you're a college student with access to an e-
> microscope,and doing a thesis or paper.
>
of the two igniter types tegger shows, the second is designed more for a
high temperature environment from what i can see. the small scale
circuitry in the components of the first igniter have much smaller
diffusion paths. the larger scale thick film device has, for
semiconductors at any rate, truly massive scale features. these are bad
for speed, but even at 10,000 rpm, that's only 166Hz, not exactly a high
frequency challenge.
#38
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
<r2000swler@hotmail.com> wrote in message
news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
I don't think the heat is too great for the ignitor. There apparently aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction temperature
and to collector voltage. When the collector junction gets hot enough, the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the device
being shorted.
But the heat required to melt the junction without the voltage stress is
much higher than your engine compartment - the melting point of silicon is
over 2500 degrees F. The silicon chips are typically soldered to the heat
sink internally, and I have personally soldered a UHF power transistor to a
large copper heatsink with an acetylene torch.
Mike
news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
I don't think the heat is too great for the ignitor. There apparently aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction temperature
and to collector voltage. When the collector junction gets hot enough, the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the device
being shorted.
But the heat required to melt the junction without the voltage stress is
much higher than your engine compartment - the melting point of silicon is
over 2500 degrees F. The silicon chips are typically soldered to the heat
sink internally, and I have personally soldered a UHF power transistor to a
large copper heatsink with an acetylene torch.
Mike
#39
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
<r2000swler@hotmail.com> wrote in message
news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
I don't think the heat is too great for the ignitor. There apparently aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction temperature
and to collector voltage. When the collector junction gets hot enough, the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the device
being shorted.
But the heat required to melt the junction without the voltage stress is
much higher than your engine compartment - the melting point of silicon is
over 2500 degrees F. The silicon chips are typically soldered to the heat
sink internally, and I have personally soldered a UHF power transistor to a
large copper heatsink with an acetylene torch.
Mike
news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
> One important point is that it looks like Honda skimps on teh heat sink
> compound. Of course the engine runs hotter then the igniter, so I am
> not at all sure that adding more thermal coupling will help. I have
> thought
> of adding a "heat pipe" tp remove heat from the igniter. I now consider
> the
> igniter a subsystem that is doomed to failure. It simply operates too
> hot
> for prolonged life.
>
I don't think the heat is too great for the ignitor. There apparently aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction temperature
and to collector voltage. When the collector junction gets hot enough, the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the device
being shorted.
But the heat required to melt the junction without the voltage stress is
much higher than your engine compartment - the melting point of silicon is
over 2500 degrees F. The silicon chips are typically soldered to the heat
sink internally, and I have personally soldered a UHF power transistor to a
large copper heatsink with an acetylene torch.
Mike
#40
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
Michael Pardee wrote:
I don't think the heat is too great for the ignitor. There apparently
aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction
temperature
and to collector voltage. When the collector junction gets hot enough,
the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the
device
being shorted.
But the heat required to melt the junction without the voltage stress
is
much higher than your engine compartment - the melting point of silicon
is
over 2500 degrees F. The silicon chips are typically soldered to the
heat
sink internally, and I have personally soldered a UHF power transistor
to a
large copper heatsink with an acetylene torch.
Mike
--------------------------------------
Yes, but you didn't put power to it until after it cooled down, and I
bet you moved a lot of air across that heatsink to keep it cool. In
service the
transisotr is switching at least 5A. I have the exact value in my
notes,
and yes it is a fast switch, the transistor is driven completly and
rapidly into full conduction so the Vec is about .5V for ~2mS every few
10s of aMsec.
Not a haeavy duty cydle by any means, but it runs, with "perfect"
heatsinking
to the block at ~195F. Those I measured actualy ran about 210~220F.
Somewhere I have the leakage versus temp from motorola and at +200F
we are getting too darn hot. I saw a Ducati pointless ignition system
that
used a flip flop to switch between 2 transitor to cut the Pd in half.
But
that system was expossed directly to the airstream. Of the people
I know who have had igniter failurs, Honda or Toyota, it has always
been in >90F weather, most frequently in stop and go traffic on the way
home.
Except for one that failed in ~-25F weather on startup. I can't prove
it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
the failure rate would drop "way down". Another failure mode that is
only slightly heat related is the piezo effect on the junction when it
switches.
I had a early JBL switch mode power amp that ate switching transistors
at fairly regular intervals. I had built, and still have, a ultrasonic
down
converter and you could plainly hear the transitors screaming at 40KHz.
I supsect that heat, plus current stress, plus the piezo effect could
explain
most igniter failures. One could always attempt to place it remotly, in
front
of the radiator to breath cool air, but I suspect the lead inductanc
would
kill you and the RFI would be "interesting".
When I needed to align my R2000 SW I needed an "ignition like"
noise source "with harmonics extending up too beyond 30MHz"
I pulled my 1991 Civic under my "long" wire antenna, and adjusted
the noise blanker. Worked much better then the puilse generator
at the shop where I work.
Terry
I don't think the heat is too great for the ignitor. There apparently
aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction
temperature
and to collector voltage. When the collector junction gets hot enough,
the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the
device
being shorted.
But the heat required to melt the junction without the voltage stress
is
much higher than your engine compartment - the melting point of silicon
is
over 2500 degrees F. The silicon chips are typically soldered to the
heat
sink internally, and I have personally soldered a UHF power transistor
to a
large copper heatsink with an acetylene torch.
Mike
--------------------------------------
Yes, but you didn't put power to it until after it cooled down, and I
bet you moved a lot of air across that heatsink to keep it cool. In
service the
transisotr is switching at least 5A. I have the exact value in my
notes,
and yes it is a fast switch, the transistor is driven completly and
rapidly into full conduction so the Vec is about .5V for ~2mS every few
10s of aMsec.
Not a haeavy duty cydle by any means, but it runs, with "perfect"
heatsinking
to the block at ~195F. Those I measured actualy ran about 210~220F.
Somewhere I have the leakage versus temp from motorola and at +200F
we are getting too darn hot. I saw a Ducati pointless ignition system
that
used a flip flop to switch between 2 transitor to cut the Pd in half.
But
that system was expossed directly to the airstream. Of the people
I know who have had igniter failurs, Honda or Toyota, it has always
been in >90F weather, most frequently in stop and go traffic on the way
home.
Except for one that failed in ~-25F weather on startup. I can't prove
it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
the failure rate would drop "way down". Another failure mode that is
only slightly heat related is the piezo effect on the junction when it
switches.
I had a early JBL switch mode power amp that ate switching transistors
at fairly regular intervals. I had built, and still have, a ultrasonic
down
converter and you could plainly hear the transitors screaming at 40KHz.
I supsect that heat, plus current stress, plus the piezo effect could
explain
most igniter failures. One could always attempt to place it remotly, in
front
of the radiator to breath cool air, but I suspect the lead inductanc
would
kill you and the RFI would be "interesting".
When I needed to align my R2000 SW I needed an "ignition like"
noise source "with harmonics extending up too beyond 30MHz"
I pulled my 1991 Civic under my "long" wire antenna, and adjusted
the noise blanker. Worked much better then the puilse generator
at the shop where I work.
Terry
#41
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
Michael Pardee wrote:
I don't think the heat is too great for the ignitor. There apparently
aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction
temperature
and to collector voltage. When the collector junction gets hot enough,
the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the
device
being shorted.
But the heat required to melt the junction without the voltage stress
is
much higher than your engine compartment - the melting point of silicon
is
over 2500 degrees F. The silicon chips are typically soldered to the
heat
sink internally, and I have personally soldered a UHF power transistor
to a
large copper heatsink with an acetylene torch.
Mike
--------------------------------------
Yes, but you didn't put power to it until after it cooled down, and I
bet you moved a lot of air across that heatsink to keep it cool. In
service the
transisotr is switching at least 5A. I have the exact value in my
notes,
and yes it is a fast switch, the transistor is driven completly and
rapidly into full conduction so the Vec is about .5V for ~2mS every few
10s of aMsec.
Not a haeavy duty cydle by any means, but it runs, with "perfect"
heatsinking
to the block at ~195F. Those I measured actualy ran about 210~220F.
Somewhere I have the leakage versus temp from motorola and at +200F
we are getting too darn hot. I saw a Ducati pointless ignition system
that
used a flip flop to switch between 2 transitor to cut the Pd in half.
But
that system was expossed directly to the airstream. Of the people
I know who have had igniter failurs, Honda or Toyota, it has always
been in >90F weather, most frequently in stop and go traffic on the way
home.
Except for one that failed in ~-25F weather on startup. I can't prove
it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
the failure rate would drop "way down". Another failure mode that is
only slightly heat related is the piezo effect on the junction when it
switches.
I had a early JBL switch mode power amp that ate switching transistors
at fairly regular intervals. I had built, and still have, a ultrasonic
down
converter and you could plainly hear the transitors screaming at 40KHz.
I supsect that heat, plus current stress, plus the piezo effect could
explain
most igniter failures. One could always attempt to place it remotly, in
front
of the radiator to breath cool air, but I suspect the lead inductanc
would
kill you and the RFI would be "interesting".
When I needed to align my R2000 SW I needed an "ignition like"
noise source "with harmonics extending up too beyond 30MHz"
I pulled my 1991 Civic under my "long" wire antenna, and adjusted
the noise blanker. Worked much better then the puilse generator
at the shop where I work.
Terry
I don't think the heat is too great for the ignitor. There apparently
aren't
any electrolytic capacitors in it, and those are the big heat sensitive
worries.
The vulnerability of transistors to heat is related to junction
temperature
and to collector voltage. When the collector junction gets hot enough,
the
reverse voltage across it can make the dopants migrate and "blur" the
junction. That spot gets hotter and eventually melts, leading to the
device
being shorted.
But the heat required to melt the junction without the voltage stress
is
much higher than your engine compartment - the melting point of silicon
is
over 2500 degrees F. The silicon chips are typically soldered to the
heat
sink internally, and I have personally soldered a UHF power transistor
to a
large copper heatsink with an acetylene torch.
Mike
--------------------------------------
Yes, but you didn't put power to it until after it cooled down, and I
bet you moved a lot of air across that heatsink to keep it cool. In
service the
transisotr is switching at least 5A. I have the exact value in my
notes,
and yes it is a fast switch, the transistor is driven completly and
rapidly into full conduction so the Vec is about .5V for ~2mS every few
10s of aMsec.
Not a haeavy duty cydle by any means, but it runs, with "perfect"
heatsinking
to the block at ~195F. Those I measured actualy ran about 210~220F.
Somewhere I have the leakage versus temp from motorola and at +200F
we are getting too darn hot. I saw a Ducati pointless ignition system
that
used a flip flop to switch between 2 transitor to cut the Pd in half.
But
that system was expossed directly to the airstream. Of the people
I know who have had igniter failurs, Honda or Toyota, it has always
been in >90F weather, most frequently in stop and go traffic on the way
home.
Except for one that failed in ~-25F weather on startup. I can't prove
it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
the failure rate would drop "way down". Another failure mode that is
only slightly heat related is the piezo effect on the junction when it
switches.
I had a early JBL switch mode power amp that ate switching transistors
at fairly regular intervals. I had built, and still have, a ultrasonic
down
converter and you could plainly hear the transitors screaming at 40KHz.
I supsect that heat, plus current stress, plus the piezo effect could
explain
most igniter failures. One could always attempt to place it remotly, in
front
of the radiator to breath cool air, but I suspect the lead inductanc
would
kill you and the RFI would be "interesting".
When I needed to align my R2000 SW I needed an "ignition like"
noise source "with harmonics extending up too beyond 30MHz"
I pulled my 1991 Civic under my "long" wire antenna, and adjusted
the noise blanker. Worked much better then the puilse generator
at the shop where I work.
Terry
#42
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
Michael Pardee wrote:
> <r2000swler@hotmail.com> wrote in message
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
>
>>One important point is that it looks like Honda skimps on teh heat sink
>>compound. Of course the engine runs hotter then the igniter, so I am
>>not at all sure that adding more thermal coupling will help. I have
>>thought
>>of adding a "heat pipe" tp remove heat from the igniter. I now consider
>>the
>>igniter a subsystem that is doomed to failure. It simply operates too
>>hot
>>for prolonged life.
>>
>
>
> I don't think the heat is too great for the ignitor. There apparently aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction temperature
> and to collector voltage. When the collector junction gets hot enough, the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the device
> being shorted.
the "blurring" is diffusion - the operating temp doesn't even get close
to melting - but diffusion is powerful stuff and it definitely destroys
semiconductors.
>
> But the heat required to melt the junction without the voltage stress is
> much higher than your engine compartment - the melting point of silicon is
> over 2500 degrees F. The silicon chips are typically soldered to the heat
> sink internally, and I have personally soldered a UHF power transistor to a
> large copper heatsink with an acetylene torch.
the two factors at play are temperature & time. if the device was
physically big enough and you solderd quick enough, there's no reason
you couldn't do it - afterall, what temperature does a silcon foundry
work at? but you got to be /quick/ if you go to high temps. or best
not at all if you want good service life.
>
> Mike
>
>
> <r2000swler@hotmail.com> wrote in message
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
>
>>One important point is that it looks like Honda skimps on teh heat sink
>>compound. Of course the engine runs hotter then the igniter, so I am
>>not at all sure that adding more thermal coupling will help. I have
>>thought
>>of adding a "heat pipe" tp remove heat from the igniter. I now consider
>>the
>>igniter a subsystem that is doomed to failure. It simply operates too
>>hot
>>for prolonged life.
>>
>
>
> I don't think the heat is too great for the ignitor. There apparently aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction temperature
> and to collector voltage. When the collector junction gets hot enough, the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the device
> being shorted.
the "blurring" is diffusion - the operating temp doesn't even get close
to melting - but diffusion is powerful stuff and it definitely destroys
semiconductors.
>
> But the heat required to melt the junction without the voltage stress is
> much higher than your engine compartment - the melting point of silicon is
> over 2500 degrees F. The silicon chips are typically soldered to the heat
> sink internally, and I have personally soldered a UHF power transistor to a
> large copper heatsink with an acetylene torch.
the two factors at play are temperature & time. if the device was
physically big enough and you solderd quick enough, there's no reason
you couldn't do it - afterall, what temperature does a silcon foundry
work at? but you got to be /quick/ if you go to high temps. or best
not at all if you want good service life.
>
> Mike
>
>
#43
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
Michael Pardee wrote:
> <r2000swler@hotmail.com> wrote in message
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
>
>>One important point is that it looks like Honda skimps on teh heat sink
>>compound. Of course the engine runs hotter then the igniter, so I am
>>not at all sure that adding more thermal coupling will help. I have
>>thought
>>of adding a "heat pipe" tp remove heat from the igniter. I now consider
>>the
>>igniter a subsystem that is doomed to failure. It simply operates too
>>hot
>>for prolonged life.
>>
>
>
> I don't think the heat is too great for the ignitor. There apparently aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction temperature
> and to collector voltage. When the collector junction gets hot enough, the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the device
> being shorted.
the "blurring" is diffusion - the operating temp doesn't even get close
to melting - but diffusion is powerful stuff and it definitely destroys
semiconductors.
>
> But the heat required to melt the junction without the voltage stress is
> much higher than your engine compartment - the melting point of silicon is
> over 2500 degrees F. The silicon chips are typically soldered to the heat
> sink internally, and I have personally soldered a UHF power transistor to a
> large copper heatsink with an acetylene torch.
the two factors at play are temperature & time. if the device was
physically big enough and you solderd quick enough, there's no reason
you couldn't do it - afterall, what temperature does a silcon foundry
work at? but you got to be /quick/ if you go to high temps. or best
not at all if you want good service life.
>
> Mike
>
>
> <r2000swler@hotmail.com> wrote in message
> news:1118859696.926058.152280@z14g2000cwz.googlegr oups.com...
>
>>One important point is that it looks like Honda skimps on teh heat sink
>>compound. Of course the engine runs hotter then the igniter, so I am
>>not at all sure that adding more thermal coupling will help. I have
>>thought
>>of adding a "heat pipe" tp remove heat from the igniter. I now consider
>>the
>>igniter a subsystem that is doomed to failure. It simply operates too
>>hot
>>for prolonged life.
>>
>
>
> I don't think the heat is too great for the ignitor. There apparently aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction temperature
> and to collector voltage. When the collector junction gets hot enough, the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the device
> being shorted.
the "blurring" is diffusion - the operating temp doesn't even get close
to melting - but diffusion is powerful stuff and it definitely destroys
semiconductors.
>
> But the heat required to melt the junction without the voltage stress is
> much higher than your engine compartment - the melting point of silicon is
> over 2500 degrees F. The silicon chips are typically soldered to the heat
> sink internally, and I have personally soldered a UHF power transistor to a
> large copper heatsink with an acetylene torch.
the two factors at play are temperature & time. if the device was
physically big enough and you solderd quick enough, there's no reason
you couldn't do it - afterall, what temperature does a silcon foundry
work at? but you got to be /quick/ if you go to high temps. or best
not at all if you want good service life.
>
> Mike
>
>
#44
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
r2000swler@hotmail.com wrote:
> Michael Pardee wrote:
>
> I don't think the heat is too great for the ignitor. There apparently
> aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction
> temperature
> and to collector voltage. When the collector junction gets hot enough,
> the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the
> device
> being shorted.
>
> But the heat required to melt the junction without the voltage stress
> is
> much higher than your engine compartment - the melting point of silicon
> is
> over 2500 degrees F. The silicon chips are typically soldered to the
> heat
> sink internally, and I have personally soldered a UHF power transistor
> to a
> large copper heatsink with an acetylene torch.
>
> Mike
> --------------------------------------
> Yes, but you didn't put power to it until after it cooled down, and I
> bet you moved a lot of air across that heatsink to keep it cool. In
> service the
> transisotr is switching at least 5A. I have the exact value in my
> notes,
> and yes it is a fast switch, the transistor is driven completly and
> rapidly into full conduction so the Vec is about .5V for ~2mS every few
> 10s of aMsec.
> Not a haeavy duty cydle by any means, but it runs, with "perfect"
> heatsinking
> to the block at ~195F. Those I measured actualy ran about 210~220F.
>
> Somewhere I have the leakage versus temp from motorola and at +200F
> we are getting too darn hot. I saw a Ducati pointless ignition system
> that
> used a flip flop to switch between 2 transitor to cut the Pd in half.
> But
> that system was expossed directly to the airstream. Of the people
> I know who have had igniter failurs, Honda or Toyota, it has always
> been in >90F weather, most frequently in stop and go traffic on the way
> home.
> Except for one that failed in ~-25F weather on startup. I can't prove
> it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
> the failure rate would drop "way down".
no proof required - it's true. google for fick's laws and the arrhenius
equation. i too have considered cooling options for my civic's igniter,
even remote mounting in a location where it's not in the air stream
heated by the exhaust or getting thermal conduction from a nice warm
cylinder head, but so far, i've just not had an appetite for the work
involved. i'm also worried about electrical noise. electrically, it
makes so much sense to have the igniter mounted in close proximity to
the coil - nice clean signal, faster switching, etc. but the reality is
that the igniter is kept so toasty warm located where it is, it's always
going to fry in short order, unless you live up in the frozen north of
course, [tegger]. i now carry a spare.
> Another failure mode that is
> only slightly heat related is the piezo effect on the junction when it
> switches.
> I had a early JBL switch mode power amp that ate switching transistors
> at fairly regular intervals. I had built, and still have, a ultrasonic
> down
> converter and you could plainly hear the transitors screaming at 40KHz.
> I supsect that heat, plus current stress, plus the piezo effect could
> explain
> most igniter failures. One could always attempt to place it remotly, in
> front
> of the radiator to breath cool air, but I suspect the lead inductanc
> would
> kill you and the RFI would be "interesting".
>
> When I needed to align my R2000 SW I needed an "ignition like"
> noise source "with harmonics extending up too beyond 30MHz"
> I pulled my 1991 Civic under my "long" wire antenna, and adjusted
> the noise blanker. Worked much better then the puilse generator
> at the shop where I work.
>
> Terry
>
> Michael Pardee wrote:
>
> I don't think the heat is too great for the ignitor. There apparently
> aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction
> temperature
> and to collector voltage. When the collector junction gets hot enough,
> the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the
> device
> being shorted.
>
> But the heat required to melt the junction without the voltage stress
> is
> much higher than your engine compartment - the melting point of silicon
> is
> over 2500 degrees F. The silicon chips are typically soldered to the
> heat
> sink internally, and I have personally soldered a UHF power transistor
> to a
> large copper heatsink with an acetylene torch.
>
> Mike
> --------------------------------------
> Yes, but you didn't put power to it until after it cooled down, and I
> bet you moved a lot of air across that heatsink to keep it cool. In
> service the
> transisotr is switching at least 5A. I have the exact value in my
> notes,
> and yes it is a fast switch, the transistor is driven completly and
> rapidly into full conduction so the Vec is about .5V for ~2mS every few
> 10s of aMsec.
> Not a haeavy duty cydle by any means, but it runs, with "perfect"
> heatsinking
> to the block at ~195F. Those I measured actualy ran about 210~220F.
>
> Somewhere I have the leakage versus temp from motorola and at +200F
> we are getting too darn hot. I saw a Ducati pointless ignition system
> that
> used a flip flop to switch between 2 transitor to cut the Pd in half.
> But
> that system was expossed directly to the airstream. Of the people
> I know who have had igniter failurs, Honda or Toyota, it has always
> been in >90F weather, most frequently in stop and go traffic on the way
> home.
> Except for one that failed in ~-25F weather on startup. I can't prove
> it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
> the failure rate would drop "way down".
no proof required - it's true. google for fick's laws and the arrhenius
equation. i too have considered cooling options for my civic's igniter,
even remote mounting in a location where it's not in the air stream
heated by the exhaust or getting thermal conduction from a nice warm
cylinder head, but so far, i've just not had an appetite for the work
involved. i'm also worried about electrical noise. electrically, it
makes so much sense to have the igniter mounted in close proximity to
the coil - nice clean signal, faster switching, etc. but the reality is
that the igniter is kept so toasty warm located where it is, it's always
going to fry in short order, unless you live up in the frozen north of
course, [tegger]. i now carry a spare.
> Another failure mode that is
> only slightly heat related is the piezo effect on the junction when it
> switches.
> I had a early JBL switch mode power amp that ate switching transistors
> at fairly regular intervals. I had built, and still have, a ultrasonic
> down
> converter and you could plainly hear the transitors screaming at 40KHz.
> I supsect that heat, plus current stress, plus the piezo effect could
> explain
> most igniter failures. One could always attempt to place it remotly, in
> front
> of the radiator to breath cool air, but I suspect the lead inductanc
> would
> kill you and the RFI would be "interesting".
>
> When I needed to align my R2000 SW I needed an "ignition like"
> noise source "with harmonics extending up too beyond 30MHz"
> I pulled my 1991 Civic under my "long" wire antenna, and adjusted
> the noise blanker. Worked much better then the puilse generator
> at the shop where I work.
>
> Terry
>
#45
Guest
Posts: n/a
Re: Unofficial FAQ: Ignition corrections
r2000swler@hotmail.com wrote:
> Michael Pardee wrote:
>
> I don't think the heat is too great for the ignitor. There apparently
> aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction
> temperature
> and to collector voltage. When the collector junction gets hot enough,
> the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the
> device
> being shorted.
>
> But the heat required to melt the junction without the voltage stress
> is
> much higher than your engine compartment - the melting point of silicon
> is
> over 2500 degrees F. The silicon chips are typically soldered to the
> heat
> sink internally, and I have personally soldered a UHF power transistor
> to a
> large copper heatsink with an acetylene torch.
>
> Mike
> --------------------------------------
> Yes, but you didn't put power to it until after it cooled down, and I
> bet you moved a lot of air across that heatsink to keep it cool. In
> service the
> transisotr is switching at least 5A. I have the exact value in my
> notes,
> and yes it is a fast switch, the transistor is driven completly and
> rapidly into full conduction so the Vec is about .5V for ~2mS every few
> 10s of aMsec.
> Not a haeavy duty cydle by any means, but it runs, with "perfect"
> heatsinking
> to the block at ~195F. Those I measured actualy ran about 210~220F.
>
> Somewhere I have the leakage versus temp from motorola and at +200F
> we are getting too darn hot. I saw a Ducati pointless ignition system
> that
> used a flip flop to switch between 2 transitor to cut the Pd in half.
> But
> that system was expossed directly to the airstream. Of the people
> I know who have had igniter failurs, Honda or Toyota, it has always
> been in >90F weather, most frequently in stop and go traffic on the way
> home.
> Except for one that failed in ~-25F weather on startup. I can't prove
> it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
> the failure rate would drop "way down".
no proof required - it's true. google for fick's laws and the arrhenius
equation. i too have considered cooling options for my civic's igniter,
even remote mounting in a location where it's not in the air stream
heated by the exhaust or getting thermal conduction from a nice warm
cylinder head, but so far, i've just not had an appetite for the work
involved. i'm also worried about electrical noise. electrically, it
makes so much sense to have the igniter mounted in close proximity to
the coil - nice clean signal, faster switching, etc. but the reality is
that the igniter is kept so toasty warm located where it is, it's always
going to fry in short order, unless you live up in the frozen north of
course, [tegger]. i now carry a spare.
> Another failure mode that is
> only slightly heat related is the piezo effect on the junction when it
> switches.
> I had a early JBL switch mode power amp that ate switching transistors
> at fairly regular intervals. I had built, and still have, a ultrasonic
> down
> converter and you could plainly hear the transitors screaming at 40KHz.
> I supsect that heat, plus current stress, plus the piezo effect could
> explain
> most igniter failures. One could always attempt to place it remotly, in
> front
> of the radiator to breath cool air, but I suspect the lead inductanc
> would
> kill you and the RFI would be "interesting".
>
> When I needed to align my R2000 SW I needed an "ignition like"
> noise source "with harmonics extending up too beyond 30MHz"
> I pulled my 1991 Civic under my "long" wire antenna, and adjusted
> the noise blanker. Worked much better then the puilse generator
> at the shop where I work.
>
> Terry
>
> Michael Pardee wrote:
>
> I don't think the heat is too great for the ignitor. There apparently
> aren't
> any electrolytic capacitors in it, and those are the big heat sensitive
> worries.
>
> The vulnerability of transistors to heat is related to junction
> temperature
> and to collector voltage. When the collector junction gets hot enough,
> the
> reverse voltage across it can make the dopants migrate and "blur" the
> junction. That spot gets hotter and eventually melts, leading to the
> device
> being shorted.
>
> But the heat required to melt the junction without the voltage stress
> is
> much higher than your engine compartment - the melting point of silicon
> is
> over 2500 degrees F. The silicon chips are typically soldered to the
> heat
> sink internally, and I have personally soldered a UHF power transistor
> to a
> large copper heatsink with an acetylene torch.
>
> Mike
> --------------------------------------
> Yes, but you didn't put power to it until after it cooled down, and I
> bet you moved a lot of air across that heatsink to keep it cool. In
> service the
> transisotr is switching at least 5A. I have the exact value in my
> notes,
> and yes it is a fast switch, the transistor is driven completly and
> rapidly into full conduction so the Vec is about .5V for ~2mS every few
> 10s of aMsec.
> Not a haeavy duty cydle by any means, but it runs, with "perfect"
> heatsinking
> to the block at ~195F. Those I measured actualy ran about 210~220F.
>
> Somewhere I have the leakage versus temp from motorola and at +200F
> we are getting too darn hot. I saw a Ducati pointless ignition system
> that
> used a flip flop to switch between 2 transitor to cut the Pd in half.
> But
> that system was expossed directly to the airstream. Of the people
> I know who have had igniter failurs, Honda or Toyota, it has always
> been in >90F weather, most frequently in stop and go traffic on the way
> home.
> Except for one that failed in ~-25F weather on startup. I can't prove
> it, but I suspect if we could reduce the temp 20 or even 10 degrees F,
> the failure rate would drop "way down".
no proof required - it's true. google for fick's laws and the arrhenius
equation. i too have considered cooling options for my civic's igniter,
even remote mounting in a location where it's not in the air stream
heated by the exhaust or getting thermal conduction from a nice warm
cylinder head, but so far, i've just not had an appetite for the work
involved. i'm also worried about electrical noise. electrically, it
makes so much sense to have the igniter mounted in close proximity to
the coil - nice clean signal, faster switching, etc. but the reality is
that the igniter is kept so toasty warm located where it is, it's always
going to fry in short order, unless you live up in the frozen north of
course, [tegger]. i now carry a spare.
> Another failure mode that is
> only slightly heat related is the piezo effect on the junction when it
> switches.
> I had a early JBL switch mode power amp that ate switching transistors
> at fairly regular intervals. I had built, and still have, a ultrasonic
> down
> converter and you could plainly hear the transitors screaming at 40KHz.
> I supsect that heat, plus current stress, plus the piezo effect could
> explain
> most igniter failures. One could always attempt to place it remotly, in
> front
> of the radiator to breath cool air, but I suspect the lead inductanc
> would
> kill you and the RFI would be "interesting".
>
> When I needed to align my R2000 SW I needed an "ignition like"
> noise source "with harmonics extending up too beyond 30MHz"
> I pulled my 1991 Civic under my "long" wire antenna, and adjusted
> the noise blanker. Worked much better then the puilse generator
> at the shop where I work.
>
> Terry
>