Re: Adding an O2 sensor?
 

Matt Ion <soundy@moltenimage.com> wrote in
news:DaVNg.536500$iF6.347125@pd7tw2no:

> sharx333 wrote:
>>>>Jim Yanik said:
>>>
>>>I doubt it would be worth the expense.
>>>Considering you would have to change the ECU in addition. That's big
>>>bucks. If you're looking for better gas mileage,changing your driving
>>>habits would be far more productive,keeping your tires inflated
>>>properly.
>>>
>>
>>
>>
>> Thanks, jim. You make a good point.
>>
>> I'm really curious about this "open" vs "closed" loop mode. Are we
>> greatly disadvantaged by always running in open loop?
>
> Well, it's worked for over 100 years... your average classic muscle
> car has virtually nothing in the way of "engine management".
>
>
>
>

Often,those "classic muscle cars" would not run well in other than optimal
weather or driving conditions.

--
Jim Yanik
jyanik
at
kua.net

Re: Adding an O2 sensor?
 

"sharx333" <emil.santos@gmail.com> wrote in
news:1158148754.494920.139830@d34g2000cwd.googlegr oups.com:

>
>> > Jim Yanik said:
>>
>> I doubt it would be worth the expense.
>> Considering you would have to change the ECU in addition. That's big
>> bucks. If you're looking for better gas mileage,changing your driving
>> habits would be far more productive,keeping your tires inflated
>> properly.
>>
>
>
> Thanks, jim. You make a good point.
>
> I'm really curious about this "open" vs "closed" loop mode. Are we
> greatly disadvantaged by always running in open loop? Or are we
> "lucky" as TeGGer says? Can't an ECU run in closed loop using just
> MAP, TPS, TA, etc sensors?
>

"closed loop" is just using feedback from the O2 sensor to continually
adjust input fuel/air mix to optimum. Fine tuning on the run.

"open loop" is just "dump enough gas in to make it run" for a wide range of
conditions. There's no correctional feedback.

Without the sensor measuring at the END of the combustion process,it's not
"closed loop".

the "loop" is; input..combustion..output..*measure output*..make CORRECTION
to input;repeat.
Without the correction,there's no "loop",it's an "open-ended" process.
The closure is the feedback corrections.

Think of the AC and thermostat in your home; you set a temp,and the AC
runs,cools the room,and the TS measures what the room temp is,and when it
reaches your setpoint,it shuts off the AC,and cycles. That's "closed
loop".

"Open loop" would be you turning on the AC and running it for 10 minutes
every hour,say on a timer.
The room MAY be close to where you want it,perhaps not.That would depend on
how hot the room was to begin,and how how it is outside.
There's no measurement and feedback control.

--
Jim Yanik
jyanik
at
kua.net

Re: Adding an O2 sensor?
 

"sharx333" <emil.santos@gmail.com> wrote in
news:1158148754.494920.139830@d34g2000cwd.googlegr oups.com:

>
>> > Jim Yanik said:
>>
>> I doubt it would be worth the expense.
>> Considering you would have to change the ECU in addition. That's big
>> bucks. If you're looking for better gas mileage,changing your driving
>> habits would be far more productive,keeping your tires inflated
>> properly.
>>
>
>
> Thanks, jim. You make a good point.
>
> I'm really curious about this "open" vs "closed" loop mode. Are we
> greatly disadvantaged by always running in open loop? Or are we
> "lucky" as TeGGer says? Can't an ECU run in closed loop using just
> MAP, TPS, TA, etc sensors?
>

"closed loop" is just using feedback from the O2 sensor to continually
adjust input fuel/air mix to optimum. Fine tuning on the run.

"open loop" is just "dump enough gas in to make it run" for a wide range of
conditions. There's no correctional feedback.

Without the sensor measuring at the END of the combustion process,it's not
"closed loop".

the "loop" is; input..combustion..output..*measure output*..make CORRECTION
to input;repeat.
Without the correction,there's no "loop",it's an "open-ended" process.
The closure is the feedback corrections.

Think of the AC and thermostat in your home; you set a temp,and the AC
runs,cools the room,and the TS measures what the room temp is,and when it
reaches your setpoint,it shuts off the AC,and cycles. That's "closed
loop".

"Open loop" would be you turning on the AC and running it for 10 minutes
every hour,say on a timer.
The room MAY be close to where you want it,perhaps not.That would depend on
how hot the room was to begin,and how how it is outside.
There's no measurement and feedback control.

--
Jim Yanik
jyanik
at
kua.net

Re: Adding an O2 sensor?
 

"sharx333" <emil.santos@gmail.com> wrote in
news:1158148754.494920.139830@d34g2000cwd.googlegr oups.com:

>
>> > Jim Yanik said:
>>
>> I doubt it would be worth the expense.
>> Considering you would have to change the ECU in addition. That's big
>> bucks. If you're looking for better gas mileage,changing your driving
>> habits would be far more productive,keeping your tires inflated
>> properly.
>>
>
>
> Thanks, jim. You make a good point.
>
> I'm really curious about this "open" vs "closed" loop mode. Are we
> greatly disadvantaged by always running in open loop? Or are we
> "lucky" as TeGGer says? Can't an ECU run in closed loop using just
> MAP, TPS, TA, etc sensors?
>

"closed loop" is just using feedback from the O2 sensor to continually
adjust input fuel/air mix to optimum. Fine tuning on the run.

"open loop" is just "dump enough gas in to make it run" for a wide range of
conditions. There's no correctional feedback.

Without the sensor measuring at the END of the combustion process,it's not
"closed loop".

the "loop" is; input..combustion..output..*measure output*..make CORRECTION
to input;repeat.
Without the correction,there's no "loop",it's an "open-ended" process.
The closure is the feedback corrections.

Think of the AC and thermostat in your home; you set a temp,and the AC
runs,cools the room,and the TS measures what the room temp is,and when it
reaches your setpoint,it shuts off the AC,and cycles. That's "closed
loop".

"Open loop" would be you turning on the AC and running it for 10 minutes
every hour,say on a timer.
The room MAY be close to where you want it,perhaps not.That would depend on
how hot the room was to begin,and how how it is outside.
There's no measurement and feedback control.

--
Jim Yanik
jyanik
at
kua.net

Re: Adding an O2 sensor?
 

Jim Yanik wrote:
>
> "closed loop" is just using feedback from the O2 sensor to continually
> adjust input fuel/air mix to optimum. Fine tuning on the run.
>
> "open loop" is just "dump enough gas in to make it run" for a wide range of
> conditions. There's no correctional feedback.
>
> Without the sensor measuring at the END of the combustion process,it's not
> "closed loop".


Thanks. I think I see now. That since the main output of the ECU is the
injector duration, then the main input (to have a true feedback
"closed" loop) is a sensor that measures the effects of combustion (O2
sensor).

So I take it you mean that based on the other sensors (MAP, TA, TPS,
PA), the ECU does no fine tuning based on real-time combustion result,
but rather only bases the injector duration on predefined "maps" in its
ROM. So, the ECU does vary the injector duration and spark timing, but
only based on what it "thinks" is best for a given situation, but would
still not be "closed loop". You really need to somehow measure the
exhaust. Is my understanding correct?

This makes sense, but isn't the O2 sensor just another input for the
ECU? Is it any different from the other sensors, that the ECU uses to
vary timing and injection? What makes O2 so special, if the responses
to it are also based on a ROM "map"?

TIA

Re: Adding an O2 sensor?
 

Jim Yanik wrote:
>
> "closed loop" is just using feedback from the O2 sensor to continually
> adjust input fuel/air mix to optimum. Fine tuning on the run.
>
> "open loop" is just "dump enough gas in to make it run" for a wide range of
> conditions. There's no correctional feedback.
>
> Without the sensor measuring at the END of the combustion process,it's not
> "closed loop".


Thanks. I think I see now. That since the main output of the ECU is the
injector duration, then the main input (to have a true feedback
"closed" loop) is a sensor that measures the effects of combustion (O2
sensor).

So I take it you mean that based on the other sensors (MAP, TA, TPS,
PA), the ECU does no fine tuning based on real-time combustion result,
but rather only bases the injector duration on predefined "maps" in its
ROM. So, the ECU does vary the injector duration and spark timing, but
only based on what it "thinks" is best for a given situation, but would
still not be "closed loop". You really need to somehow measure the
exhaust. Is my understanding correct?

This makes sense, but isn't the O2 sensor just another input for the
ECU? Is it any different from the other sensors, that the ECU uses to
vary timing and injection? What makes O2 so special, if the responses
to it are also based on a ROM "map"?

TIA

Re: Adding an O2 sensor?
 

Jim Yanik wrote:
>
> "closed loop" is just using feedback from the O2 sensor to continually
> adjust input fuel/air mix to optimum. Fine tuning on the run.
>
> "open loop" is just "dump enough gas in to make it run" for a wide range of
> conditions. There's no correctional feedback.
>
> Without the sensor measuring at the END of the combustion process,it's not
> "closed loop".


Thanks. I think I see now. That since the main output of the ECU is the
injector duration, then the main input (to have a true feedback
"closed" loop) is a sensor that measures the effects of combustion (O2
sensor).

So I take it you mean that based on the other sensors (MAP, TA, TPS,
PA), the ECU does no fine tuning based on real-time combustion result,
but rather only bases the injector duration on predefined "maps" in its
ROM. So, the ECU does vary the injector duration and spark timing, but
only based on what it "thinks" is best for a given situation, but would
still not be "closed loop". You really need to somehow measure the
exhaust. Is my understanding correct?

This makes sense, but isn't the O2 sensor just another input for the
ECU? Is it any different from the other sensors, that the ECU uses to
vary timing and injection? What makes O2 so special, if the responses
to it are also based on a ROM "map"?

TIA

Re: Adding an O2 sensor?
 

sharx333 wrote:
>>> Jim Yanik said:
>> I doubt it would be worth the expense.
>> Considering you would have to change the ECU in addition. That's big bucks.
>> If you're looking for better gas mileage,changing your driving habits would
>> be far more productive,keeping your tires inflated properly.
>>
>
>
> Thanks, jim. You make a good point.
>
> I'm really curious about this "open" vs "closed" loop mode. Are we
> greatly disadvantaged by always running in open loop? Or are we "lucky"
> as TeGGer says? Can't an ECU run in closed loop using just MAP, TPS,
> TA, etc sensors?
>

Closed loop is the way to optimize for low emissions and good fuel
economy. Open loop certainly can work. Most cars manufactured before
1980 were open loop systems be they carbs or early fuel injection.

For those countries where leaded fuel continued to be available the open
loop style carried on for a long time.

John

Re: Adding an O2 sensor?
 

sharx333 wrote:
>>> Jim Yanik said:
>> I doubt it would be worth the expense.
>> Considering you would have to change the ECU in addition. That's big bucks.
>> If you're looking for better gas mileage,changing your driving habits would
>> be far more productive,keeping your tires inflated properly.
>>
>
>
> Thanks, jim. You make a good point.
>
> I'm really curious about this "open" vs "closed" loop mode. Are we
> greatly disadvantaged by always running in open loop? Or are we "lucky"
> as TeGGer says? Can't an ECU run in closed loop using just MAP, TPS,
> TA, etc sensors?
>

Closed loop is the way to optimize for low emissions and good fuel
economy. Open loop certainly can work. Most cars manufactured before
1980 were open loop systems be they carbs or early fuel injection.

For those countries where leaded fuel continued to be available the open
loop style carried on for a long time.

John

Re: Adding an O2 sensor?
 

sharx333 wrote:
>>> Jim Yanik said:
>> I doubt it would be worth the expense.
>> Considering you would have to change the ECU in addition. That's big bucks.
>> If you're looking for better gas mileage,changing your driving habits would
>> be far more productive,keeping your tires inflated properly.
>>
>
>
> Thanks, jim. You make a good point.
>
> I'm really curious about this "open" vs "closed" loop mode. Are we
> greatly disadvantaged by always running in open loop? Or are we "lucky"
> as TeGGer says? Can't an ECU run in closed loop using just MAP, TPS,
> TA, etc sensors?
>

Closed loop is the way to optimize for low emissions and good fuel
economy. Open loop certainly can work. Most cars manufactured before
1980 were open loop systems be they carbs or early fuel injection.

For those countries where leaded fuel continued to be available the open
loop style carried on for a long time.

John

Re: Adding an O2 sensor?
 

sharx333 wrote:
> Jim Yanik wrote:
>> "closed loop" is just using feedback from the O2 sensor to continually
>> adjust input fuel/air mix to optimum. Fine tuning on the run.
>>
>> "open loop" is just "dump enough gas in to make it run" for a wide range of
>> conditions. There's no correctional feedback.
>>
>> Without the sensor measuring at the END of the combustion process,it's not
>> "closed loop".
>
>
> Thanks. I think I see now. That since the main output of the ECU is the
> injector duration, then the main input (to have a true feedback
> "closed" loop) is a sensor that measures the effects of combustion (O2
> sensor).

yes.

>
> So I take it you mean that based on the other sensors (MAP, TA, TPS,
> PA), the ECU does no fine tuning based on real-time combustion result,
> but rather only bases the injector duration on predefined "maps" in its
> ROM.

yes.

> So, the ECU does vary the injector duration and spark timing, but
> only based on what it "thinks" is best for a given situation, but would
> still not be "closed loop".

yes.

> You really need to somehow measure the
> exhaust. Is my understanding correct?

absolutely.

>
> This makes sense, but isn't the O2 sensor just another input for the
> ECU?

yes.

> Is it any different from the other sensors, that the ECU uses to
> vary timing and injection? What makes O2 so special, if the responses
> to it are also based on a ROM "map"?

based on the maps and readings of the sensors, including lambda, the ecu
can then compute in real time the precise amount of fuel to be injected.

if you're interested, there's an open source injector project out there
called [charmingly] "megasquirt". once googled, you can read the whole
nine yards about how injection works, even source code an ecu runs on.

Re: Adding an O2 sensor?
 

sharx333 wrote:
> Jim Yanik wrote:
>> "closed loop" is just using feedback from the O2 sensor to continually
>> adjust input fuel/air mix to optimum. Fine tuning on the run.
>>
>> "open loop" is just "dump enough gas in to make it run" for a wide range of
>> conditions. There's no correctional feedback.
>>
>> Without the sensor measuring at the END of the combustion process,it's not
>> "closed loop".
>
>
> Thanks. I think I see now. That since the main output of the ECU is the
> injector duration, then the main input (to have a true feedback
> "closed" loop) is a sensor that measures the effects of combustion (O2
> sensor).

yes.

>
> So I take it you mean that based on the other sensors (MAP, TA, TPS,
> PA), the ECU does no fine tuning based on real-time combustion result,
> but rather only bases the injector duration on predefined "maps" in its
> ROM.

yes.

> So, the ECU does vary the injector duration and spark timing, but
> only based on what it "thinks" is best for a given situation, but would
> still not be "closed loop".

yes.

> You really need to somehow measure the
> exhaust. Is my understanding correct?

absolutely.

>
> This makes sense, but isn't the O2 sensor just another input for the
> ECU?

yes.

> Is it any different from the other sensors, that the ECU uses to
> vary timing and injection? What makes O2 so special, if the responses
> to it are also based on a ROM "map"?

based on the maps and readings of the sensors, including lambda, the ecu
can then compute in real time the precise amount of fuel to be injected.

if you're interested, there's an open source injector project out there
called [charmingly] "megasquirt". once googled, you can read the whole
nine yards about how injection works, even source code an ecu runs on.

Re: Adding an O2 sensor?
 

sharx333 wrote:
> Jim Yanik wrote:
>> "closed loop" is just using feedback from the O2 sensor to continually
>> adjust input fuel/air mix to optimum. Fine tuning on the run.
>>
>> "open loop" is just "dump enough gas in to make it run" for a wide range of
>> conditions. There's no correctional feedback.
>>
>> Without the sensor measuring at the END of the combustion process,it's not
>> "closed loop".
>
>
> Thanks. I think I see now. That since the main output of the ECU is the
> injector duration, then the main input (to have a true feedback
> "closed" loop) is a sensor that measures the effects of combustion (O2
> sensor).

yes.

>
> So I take it you mean that based on the other sensors (MAP, TA, TPS,
> PA), the ECU does no fine tuning based on real-time combustion result,
> but rather only bases the injector duration on predefined "maps" in its
> ROM.

yes.

> So, the ECU does vary the injector duration and spark timing, but
> only based on what it "thinks" is best for a given situation, but would
> still not be "closed loop".

yes.

> You really need to somehow measure the
> exhaust. Is my understanding correct?

absolutely.

>
> This makes sense, but isn't the O2 sensor just another input for the
> ECU?

yes.

> Is it any different from the other sensors, that the ECU uses to
> vary timing and injection? What makes O2 so special, if the responses
> to it are also based on a ROM "map"?

based on the maps and readings of the sensors, including lambda, the ecu
can then compute in real time the precise amount of fuel to be injected.

if you're interested, there's an open source injector project out there
called [charmingly] "megasquirt". once googled, you can read the whole
nine yards about how injection works, even source code an ecu runs on.

Re: Adding an O2 sensor?
 

"sharx333" <emil.santos@gmail.com> wrote in
news:1158179035.612237.136510@i42g2000cwa.googlegr oups.com:

>
> Jim Yanik wrote:
>>
>> "closed loop" is just using feedback from the O2 sensor to
>> continually adjust input fuel/air mix to optimum. Fine tuning on the
>> run.
>>
>> "open loop" is just "dump enough gas in to make it run" for a wide
>> range of conditions. There's no correctional feedback.
>>
>> Without the sensor measuring at the END of the combustion
>> process,it's not "closed loop".
>
>
> Thanks. I think I see now. That since the main output of the ECU is
> the injector duration, then the main input (to have a true feedback
> "closed" loop) is a sensor that measures the effects of combustion (O2
> sensor).
>
> So I take it you mean that based on the other sensors (MAP, TA, TPS,
> PA), the ECU does no fine tuning based on real-time combustion result,
> but rather only bases the injector duration on predefined "maps" in
> its ROM. So, the ECU does vary the injector duration and spark timing,
> but only based on what it "thinks" is best for a given situation, but
> would still not be "closed loop". You really need to somehow measure
> the exhaust. Is my understanding correct?

Excellent!
>
> This makes sense, but isn't the O2 sensor just another input for the
> ECU? Is it any different from the other sensors, that the ECU uses to
> vary timing and injection? What makes O2 so special, if the responses
> to it are also based on a ROM "map"?

Well,the desired end result is complete combustion(a clean exhaust),and
exhaust O2 content is an indication of how well that's happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this feedback
corrects for it.it also allows for individual cylinders' injectors to be
corrected,compensating for differing air flow thru the cylinders.They are
not necessarily all equal!)


I believe there may be two 'maps".
One for open-loop,and one for when everything warms to operating temp.
The 2nd map would be much simpler,and smaller in data size,or just a
refinement on (or corrections for) the primary map.
It's like the ECU first sets injector duration for the TPS,IAT,MAP and RPM
via the map,and -then- looks at O2S data and fine-tunes if needed (at op
temp) for optimal exhaust O2 content. It also minimizes the work the
catalytic has to do,-and makes it last longer.

It does take some amount of time to balance the loop once a variable is
changed.(like throttle position or intake air temp)
Loop response cannot be instant,there's always some hysteresis,but it's
inconsequential,until the O2 sensor gets "slow" in it's response(degrades).

OBD-II systems supposedly measure this O2S response time and set a trouble
code (and CEL)if it gets too long(or fails),and also uses a 2nd O2 sensor
to back up the first sensor and monitor the catalytic converter's
performance to ensure low emissions.


--
Jim Yanik
jyanik
at
kua.net

Re: Adding an O2 sensor?
 

"sharx333" <emil.santos@gmail.com> wrote in
news:1158179035.612237.136510@i42g2000cwa.googlegr oups.com:

>
> Jim Yanik wrote:
>>
>> "closed loop" is just using feedback from the O2 sensor to
>> continually adjust input fuel/air mix to optimum. Fine tuning on the
>> run.
>>
>> "open loop" is just "dump enough gas in to make it run" for a wide
>> range of conditions. There's no correctional feedback.
>>
>> Without the sensor measuring at the END of the combustion
>> process,it's not "closed loop".
>
>
> Thanks. I think I see now. That since the main output of the ECU is
> the injector duration, then the main input (to have a true feedback
> "closed" loop) is a sensor that measures the effects of combustion (O2
> sensor).
>
> So I take it you mean that based on the other sensors (MAP, TA, TPS,
> PA), the ECU does no fine tuning based on real-time combustion result,
> but rather only bases the injector duration on predefined "maps" in
> its ROM. So, the ECU does vary the injector duration and spark timing,
> but only based on what it "thinks" is best for a given situation, but
> would still not be "closed loop". You really need to somehow measure
> the exhaust. Is my understanding correct?

Excellent!
>
> This makes sense, but isn't the O2 sensor just another input for the
> ECU? Is it any different from the other sensors, that the ECU uses to
> vary timing and injection? What makes O2 so special, if the responses
> to it are also based on a ROM "map"?

Well,the desired end result is complete combustion(a clean exhaust),and
exhaust O2 content is an indication of how well that's happening.
They are real-time corrections,and measure ACTUAL exhaust output.
(if a plug misfires,or a input-condition sensor is inaccurate,this feedback
corrects for it.it also allows for individual cylinders' injectors to be
corrected,compensating for differing air flow thru the cylinders.They are
not necessarily all equal!)


I believe there may be two 'maps".
One for open-loop,and one for when everything warms to operating temp.
The 2nd map would be much simpler,and smaller in data size,or just a
refinement on (or corrections for) the primary map.
It's like the ECU first sets injector duration for the TPS,IAT,MAP and RPM
via the map,and -then- looks at O2S data and fine-tunes if needed (at op
temp) for optimal exhaust O2 content. It also minimizes the work the
catalytic has to do,-and makes it last longer.

It does take some amount of time to balance the loop once a variable is
changed.(like throttle position or intake air temp)
Loop response cannot be instant,there's always some hysteresis,but it's
inconsequential,until the O2 sensor gets "slow" in it's response(degrades).

OBD-II systems supposedly measure this O2S response time and set a trouble
code (and CEL)if it gets too long(or fails),and also uses a 2nd O2 sensor
to back up the first sensor and monitor the catalytic converter's
performance to ensure low emissions.


--
Jim Yanik
jyanik
at
kua.net