Im anonymous

I don't know if I missed something long ago, but I discovered while in
stop and go interstate traffic that my Accord *might* be adjusting
engine RPM on it's own during upshifts.
For example, while I'm disengaging the clutch and shifting to the next
highest gear, the engine RPM drops some but not all the way to idle.
Usually between 1500 and 2000 or so. And I found that if I allow the
engine RPM to settle (less than a second), and just let the clutch out
WITHOUT gas, it drops right in perfectly.
I haven't had a chance to test it out any more since yesterday since I
drove my old car today, but does this seem right? Seems like
something they should be doing if they're not. I've had the car less
than 4 months, it's a 6 speed V6.

George Macdonald

On 30 Apr 2004 06:29:24 -0700, acctforjunk@yahoo.com (Im anonymous) wrote:

>I don't know if I missed something long ago, but I discovered while in
>stop and go interstate traffic that my Accord *might* be adjusting
>engine RPM on it's own during upshifts.
>For example, while I'm disengaging the clutch and shifting to the next
>highest gear, the engine RPM drops some but not all the way to idle.
>Usually between 1500 and 2000 or so. And I found that if I allow the
>engine RPM to settle (less than a second), and just let the clutch out
>WITHOUT gas, it drops right in perfectly.
>I haven't had a chance to test it out any more since yesterday since I
>drove my old car today, but does this seem right? Seems like
>something they should be doing if they're not. I've had the car less
>than 4 months, it's a 6 speed V6.

Hard to envisage exactly the conditions you're describing but if most
noticeable in traffic/low rpms situations, certainly most modern engine
management systems will not abruptly throttle the engine, when you let off
the accelerator, for emissions reasons. It's also possible that Honda did
not engineer the flywheel weight of the V6 MT properly for a manual
transmission.<shrug>

What I've noticed in my '99 Integra is that, in say traffic, when I coast
in neutral occasionally (bad driving practice but in traffic saves wear on
the clutch/gears) , the engine will not drop below 1000rpm as long as the
car is moving. With our 2K Accord 4L Coupe, if the engine is cold, when
you declutch to change gear, the engine actually sounds like it's racing -
its not much, say 1500rpm, but is noticeable compared with its behavior
when hot.

I haven't been able to confirm this but I've also been told that some
recent engines are set to a high "idle speed" on gear changes during the
1st 5K or so miles. I haven't been able to find any docs to back this up
though so it could be just a dealer story to placate a persnickety
customer. Certainly the next phase of "emissions controls" is going after
various aspects of engine running regime -- moderate & hard acceleration,
warm-up, engine braking -- which could make the drivability ugly.
Apparently some auto-makers are back to that awful (70s era) air-pump
device to cope with this - dunno about Honda. I guess bureaucrats need
jobs too.:-)

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

Tegger®

George Macdonald <fammacd=!SPAM^nothanks@tellurian.com> spake unto the
masses in news:9nt690hkk91219pe7tr0jc3ohbkstd6494@4ax.com:

> Certainly the next phase of "emissions
> controls" is going after various aspects of engine running regime --
> moderate & hard acceleration, warm-up, engine braking -- which could
> make the drivability ugly. Apparently some auto-makers are back to
> that awful (70s era) air-pump device to cope with this - dunno about
> Honda. I guess bureaucrats need jobs too.:-)



Yeah. They're not happy with a 99% reduction in emissions. They want 99.9%,
cost and reasonability be damned!

--
TeGGeR®

The Unofficial Honda FAQ
http://www3.telus.net/public/johnings/faq.html

How to find anything on the Internet or in Usenet Groups:
www.google.com
www.groups.google.com

Im anonymous

George Macdonald <fammacd=!SPAM^nothanks@tellurian.com> wrote in message news:<9nt690hkk91219pe7tr0jc3ohbkstd6494@4ax.com>. ..
> On 30 Apr 2004 06:29:24 -0700, acctforjunk@yahoo.com (Im anonymous) wrote:

Sorry for overexplaining it. What I was getting at is it seems like
when I shifted, the engine sets its RPM to what the transmission side
of the clutch would be spinning at, ie. the clutch engages perfectly
with virtually no slip. Of course this means I keep my foot off the
gas until the clutch is engaged.

I haven't driven it since, but I'll check it out more when I do. I
think it's cool if this is what the car is really doing. I seem to
have a problem with this particular car on judging how much gas to
give it when shifting.

>
> ><snip>

> Hard to envisage exactly the conditions you're describing but if most
> noticeable in traffic/low rpms situations, certainly most modern engine
> management systems will not abruptly throttle the engine, when you let off
> the accelerator, for emissions reasons. It's also possible that Honda did
> not engineer the flywheel weight of the V6 MT properly for a manual
> transmission.<shrug>
>
> What I've noticed in my '99 Integra is that, in say traffic, when I coast
> in neutral occasionally (bad driving practice but in traffic saves wear on
> the clutch/gears) , the engine will not drop below 1000rpm as long as the
> car is moving. With our 2K Accord 4L Coupe, if the engine is cold, when
> you declutch to change gear, the engine actually sounds like it's racing -
> its not much, say 1500rpm, but is noticeable compared with its behavior
> when hot.
>
> I haven't been able to confirm this but I've also been told that some
> recent engines are set to a high "idle speed" on gear changes during the
> 1st 5K or so miles. I haven't been able to find any docs to back this up
> though so it could be just a dealer story to placate a persnickety
> customer. Certainly the next phase of "emissions controls" is going after
> various aspects of engine running regime -- moderate & hard acceleration,
> warm-up, engine braking -- which could make the drivability ugly.
> Apparently some auto-makers are back to that awful (70s era) air-pump
> device to cope with this - dunno about Honda. I guess bureaucrats need
> jobs too.:-)
>
> Rgds, George Macdonald
>
> "Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

Pars

Not sure what your getting at, but a friend of mine has a standard 1.8T
Passat which is drive by wire.The Passat, will acutally modulate the
engine's rpm when the clutch is being engaged to assisst with shifting.
Considering the weight of car and the little 1.8T engine, the help with
intial clutch take-up is a bonus.

Regarding your V6 standard Accord. Having to wait allmost a second in
order for the engine to wind down seems a little excessive in stop and go
driving. I suppose the V6's excessive torque can make for an abrupt up
, unless the engine is completely idling (I defently don't have that
problem with my teenie 106hp DX engine).

In normal situtation, up shift's on a standard tranny can be made smooth
if you're willing to ride the clutch a bit during take-up. Also, it's good
driving practice to be completely off the accelerator before going down on
the clutch. If you speed up the shifting process, going down on the clutch
and letting off the gas can seem juxtapositoned, but when you slow things
down, your right foot should be completely off the gas before going down
on the clutch with your left foot (unless you're blipping...)

Pars


Im anonymous wrote:

> I don't know if I missed something long ago, but I discovered while in
> stop and go interstate traffic that my Accord *might* be adjusting
> engine RPM on it's own during upshifts.
> For example, while I'm disengaging the clutch and shifting to the next
> highest gear, the engine RPM drops some but not all the way to idle.
> Usually between 1500 and 2000 or so. And I found that if I allow the
> engine RPM to settle (less than a second), and just let the clutch out
> WITHOUT gas, it drops right in perfectly.
> I haven't had a chance to test it out any more since yesterday since I
> drove my old car today, but does this seem right? Seems like
> something they should be doing if they're not. I've had the car less
> than 4 months, it's a 6 speed V6.

Im anonymous

Yes, that's it, it's modulating the engine RPM when I shift. I
checked it out more this last weekend, and that's definatly what it's
doing. If I don't give it gas until the clutch is engaged or almost
all the way engaged, usually I can hardly tell the clutch was engaged,
ie, it doesn't immediately pull the engine RPM down or speed it up to
match the road speed/gear ratio.

Pars <"sdaro(remove)"@hotmail.com> wrote in message news:<4093B479.E0A85105@hotmail.com>...
> Not sure what your getting at, but a friend of mine has a standard 1.8T
> Passat which is drive by wire.The Passat, will acutally modulate the
> engine's rpm when the clutch is being engaged to assisst with shifting.
> Considering the weight of car and the little 1.8T engine, the help with
> intial clutch take-up is a bonus.
>
> Regarding your V6 standard Accord. Having to wait allmost a second in
> order for the engine to wind down seems a little excessive in stop and go
> driving. I suppose the V6's excessive torque can make for an abrupt up
> , unless the engine is completely idling (I defently don't have that
> problem with my teenie 106hp DX engine).
>
> In normal situtation, up shift's on a standard tranny can be made smooth
> if you're willing to ride the clutch a bit during take-up. Also, it's good
> driving practice to be completely off the accelerator before going down on
> the clutch. If you speed up the shifting process, going down on the clutch
> and letting off the gas can seem juxtapositoned, but when you slow things
> down, your right foot should be completely off the gas before going down
> on the clutch with your left foot (unless you're blipping...)
>
> Pars
>

w_tom

I don't understand the mystery? This holding the engine
near to what should be the necessary RPM was standard even in
carburetor cars. With electronics, the concept is controlled
better. But the concept is older than Honda made cars.

Im anonymous wrote:
> Yes, that's it, it's modulating the engine RPM when I shift. I
> checked it out more this last weekend, and that's definatly what
> it's doing. If I don't give it gas until the clutch is engaged or
> almost all the way engaged, usually I can hardly tell the clutch
> was engaged, ie, it doesn't immediately pull the engine RPM down
> or speed it up to match the road speed/gear ratio.

JXStern

On Mon, 03 May 2004 12:08:34 -0400, w_tom <w_tom1@hotmail.com> wrote:
> I don't understand the mystery? This holding the engine
>near to what should be the necessary RPM was standard even in
>carburetor cars. With electronics, the concept is controlled
>better. But the concept is older than Honda made cars.

Name one carbureted car that did this.

Mine sure didn't (Fiat 124, Honda Accord 87), and I never heard of it,
unless something like the ancient Porsche Tiptronic did that circa
1970. I think my old Accord was at least advanced enough to keep the
RPM up around 1200 if, well, I'm not sure what it knew about road
speed or gearing, but I think the number was constant, and might often
enough approximate where the next upshift should be.

Say, OP, what about downshifts, does it approximate the RPM on those?



J.

w_tom

Ford Capri (using Holley 5210C carburetors). 1980 Honda
Accord. Forgot which one it was, but the shop manual for one
carburetor even gave a dimension for setting the dashpot.

JXStern wrote:
> Name one carbureted car that did this.
>
> Mine sure didn't (Fiat 124, Honda Accord 87), and I never heard of
> it, unless something like the ancient Porsche Tiptronic did that
> circa 1970. I think my old Accord was at least advanced enough
> to keep the RPM up around 1200 if, well, I'm not sure what it knew
> about road speed or gearing, but I think the number was constant,
> and might often enough approximate where the next upshift should
> be.
>
> Say, OP, what about downshifts, does it approximate the RPM on those?

George Macdonald

On Tue, 04 May 2004 18:18:21 -0400, w_tom <w_tom1@hotmail.com> wrote:

> Ford Capri (using Holley 5210C carburetors). 1980 Honda
>Accord. Forgot which one it was, but the shop manual for one
>carburetor even gave a dimension for setting the dashpot.

I thought the dashpots were just a damping device, related to manifold
vacuum, to prevent abrupt throttle shut-off and the resulting emissions
burp. I've never heard of it being linked to road speed and gearing.

>JXStern wrote:
>> Name one carbureted car that did this.
>>
>> Mine sure didn't (Fiat 124, Honda Accord 87), and I never heard of
>> it, unless something like the ancient Porsche Tiptronic did that
>> circa 1970. I think my old Accord was at least advanced enough
>> to keep the RPM up around 1200 if, well, I'm not sure what it knew
>> about road speed or gearing, but I think the number was constant,
>> and might often enough approximate where the next upshift should
>> be.
>>
>> Say, OP, what about downshifts, does it approximate the RPM on those?

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

w_tom

The dashpot also did that. On the Holley's an additional
bypass valve was also installed that would also eliminate
backfiring. Its operation was also controlled by manifold
vacuum. This valve was routinely destroyed when Pinto
camshafts wore down (due to missing oil holes eliminated by
Henry Ford in his American versions of that engine).

But the dashpot was adjusted unique for manual transmission
cars. Other carburetors used a more sophisticated system based
upon engine manifold vacuum. Granted it was not as
sophisticated as done today. But then everything back then
was a crude mechanical solution. No it was not linked to road
speed and gearing. That is the more sophisticated version of
something done decades ago. Just like carburetors could never
accomplish what fuel injection does.

The new version goes by names such as electronic throttle
control. New and fancier ways of doing the same old thing. A
function even back then so subtle that most people don't even
knew it existed or could be adjusted.

George Macdonald wrote:
> I thought the dashpots were just a damping device, related to
> manifold vacuum, to prevent abrupt throttle shut-off and the
> resulting emissions burp. I've never heard of it being linked
> to road speed and gearing.

Im anonymous

JXStern <JXSternChangeX2R@gte.net> wrote in message news:<rvjf905hd0to7dokdcpqes1iru2vgvgahv@4ax.com>. ..
> On Mon, 03 May 2004 12:08:34 -0400, w_tom <w_tom1@hotmail.com> wrote:
>
> 1970. I think my old Accord was at least advanced enough to keep the
> RPM up around 1200 if, well, I'm not sure what it knew about road
> speed or gearing, but I think the number was constant, and might often
> enough approximate where the next upshift should be.
>
> Say, OP, what about downshifts, does it approximate the RPM on those?
>
>
>
> J.

I didn't think it did. When I drove it home from work I tried, and
no, it doesn't. Then I realized....how would it know if you're
upshifting or downshifting? So no, it doesn't. Besides, I only
downshift if my road speed is decreasing. I never downshift for
engine braking. Why put wear on your clutch when your brakes are so
much easier and cheaper to fix.

JXStern

On Wed, 05 May 2004 14:09:25 -0400, w_tom <w_tom1@hotmail.com> wrote:
> But the dashpot was adjusted unique for manual transmission
>cars. Other carburetors used a more sophisticated system based
>upon engine manifold vacuum. Granted it was not as
>sophisticated as done today.

We're still trying to determine if it *is* done today.

Basing it on vacuum might avoid quick engine speed changes for
pollution reasons, and that might have *roughly* the effect of keeping
engine speed closer to the sync range on upshifts, but that would be a
a side-effect -- as I pointed out, it wouldn't help a bit on
downshifts!

J.