Mystery Power Burst....

[Steady Eddie]

Back in the day when cars had carbs instead of
fancy multi-port fuel injection, the 4-bbl on a Coaches' gas engine had an accelerator pump as
well as a power enrichment circuit, all living in the bowels of the carb. When you floored it
the pump squirted in some raw gas and the PE
circuit kicked in and away you went, up the hill or down the on-ramp. The newer Vortecs also
have a PE circuit built-in for the same reasons that the old school carb had it. Only this time it is a function of the OBD2 computer to control it. There is no direct mechanical linkage between the throttle pedal and the fuel injection. It is electronic. Within the brain-box there is a PE timer-on, that can be set.
The timer values are pre-set in the software to run for one minute. Or 60 seconds. This timer has to time out (run) BEFORE the PE circuit comes on (or kicks in). It is a kind of built in governor. And it explains why, on a very long hill, after a minute's time of nearly WOT, there happens a small burst of new found power.
Like a passing gear almost. I can time it on my watch. One minute.

The OBD2-controlled LT1 Chevy Hi-performance
engine has this PE timer set to Zero.

The point is that you do not drive your Coach, the computer does...and this is one example.
And it also explains why, sometimes, when you nail into the gas, nothing much happens...

[Steady Eddie]

Back in the day when cars had carbs instead of
fancy multi-port fuel injection, the 4-bbl on a Coaches' gas engine had an accelerator pump as
well as a power enrichment circuit, all living in the bowels of the carb. When you floored it
the pump squirted in some raw gas and the PE
circuit kicked in and away you went, up the hill or down the on-ramp. The newer Vortecs also
have a PE circuit built-in for the same reasons that the old school carb had it. Only this time it is a function of the OBD2 computer to control it. There is no direct mechanical linkage between the throttle pedal and the fuel injection. It is electronic. Within the brain-box there is a PE timer-on, that can be set.
The timer values are pre-set in the software to run for one minute. Or 60 seconds. This timer has to time out (run) BEFORE the PE circuit comes on (or kicks in). It is a kind of built in governor. And it explains why, on a very long hill, after a minute's time of nearly WOT, there happens a small burst of new found power.
Like a passing gear almost. I can time it on my watch. One minute.

The OBD2-controlled LT1 Chevy Hi-performance
engine has this PE timer set to Zero.

The point is that you do not drive your Coach, the computer does...and this is one example.
And it also explains why, sometimes, when you nail into the gas, nothing much happens...

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Steady Eddie:
And it also explains why, sometimes, when you nail into the gas, nothing much happens... </div></BLOCKQUOTE>When I nail my gas pedal my smile goes from 0 to 60 in .04587 seconds.

[Captain Bud]

I sought of remember blowing past a Wnnie with a Blue Tank hung off the ladder, I guess his computer was taking a nap.....

[BellaBo]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">When I nail my gas pedal my smile goes from 0 to 60 in .04587 seconds. </div></BLOCKQUOTE>
And the wallet goes from 60 to 0 just about as fast

[Steady Eddie]

So, we have this issue, put in there by the GM
Powertrain Group to protect the drivetrain from
operator/driver abuse. It is a part of the "torque management" sub-system and it is based on a % value of the position of the module's electronic throttle's position change.

I am big on mechanical tweaks to cure electronic problems, such as spark retard.
The CAI, the T-stat mod and etc. were all the product of several movements and the reading of the Service Manuals.

I believe if you en-VISION a raw egg between your gas pedal foot and the gas pedal and advance the pedal to keep from breaking the egg, then you can defeat this parameter.

You must mimic the gradual throttle increase of the cruise control. This results in greater fuel
economy by default. Ever notice, while in cruise
control, the little rolling hills can be overcome without ever getting into the PE circuit??

[TandW]

My foot gets better milage than the CC. My CC has too much gain. When taking on small hills it actually increases speed by 1 to 2 mph unlike all my other GM products. In the motorhome I only use CC on the flats because of this gain. Anybody know how to reduce this gain?

[max49]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Ever notice, while in cruise
control, the little rolling hills can be overcome without ever getting into the PE circuit?? </div></BLOCKQUOTE>


Not my cruise control. If I lose 1 MPH , mine floors it, slams the downshifts, and is 'on a mission and very aggressive.' It shows no mercy on the engine or transmission.
My CC must work alot different than Steady Eddies.
That's why I don't like to use it too much in Co. It has no patience ( or brains) what so ever. It does'nt like 69 MPH if it's set to 70

[Steady Eddie]

"...My CC has too much gain..."
=========================
Chief--
Mine does it, too. Don't know if it is easily
fixable..the controller may live inside the
brain-box. One thing I'd like you to check,
when in cruise does your rig (on a drop from set-point) increase either the gas pedal position or the engine RPMs to get back up to
set MPH??? I got the chance to study mine for
3000 miles and it sure seems like it'll pick up
speed back to set WITHOUT showing on the Tach
OR pedal...weird...Max says his works different.

[rgrstndgby]

Eddie says....<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">and it sure seems like it'll pick up
speed back to set WITHOUT showing on the Tach </div></BLOCKQUOTE>

Well then, don't you reckon that you are getting some change in the converter lockup, or some reduction of slipage in the trannie.?. What you are describing "shouldnt" be possible with a stick shift.( I know you dont have one, just using that as a "base" example!!).rgr..

[Steady Eddie]

rgr---

I hear ya..

But. I think (don't really know) that for
these small amounts of over-the-road speeds
back up to set-point, the fuel injectors
simply add more fuel (not air) until it gets there. In other words it *enrichens* the mix.
More towards 12 to 1 instead of 14.7 to 1 A/F
Ratio. That is how it could possibly increase
power at a given RPM, and also, increase road speed.

[Bob (WA0MQE)]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">From Max... Not my cruise control. If I lose 1 MPH , mine floors it, slams the downshifts, and is 'on a mission and very aggressive.' It shows no mercy on the engine or transmission. </div></BLOCKQUOTE>Mine does the same thing. You'd think for the cost of this chassis they could come up with a better cruise control, like one that would learn your driving habits and then when in CC operate accordingly.

[rgrstndgby]

Eddie says...<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">That is how it could possibly increase
power at a given RPM, and also, increase road speed. </div></BLOCKQUOTE>

SE, lets assume that the trannie and converter are both "locked"..the ONLY way to increase speed, is to increase RPM.. enrichment may provide more power, and the ability to pull more MPH, but without more RPM it can't increase speed.. Whadda ya think?? Ive noticed, but havnt paid alot of attention to, a "slight surge", but Im pretty sure its a slight converter "unlock", and thus a slight RPM increase.. rgr...

[Steady Eddie]

rgr--

When you step up and buy a W-Series WCC, one of
the (many) "bonus" things that you get is an Allison with a lock-up convertor. My Coach was built with an old-school, all-hydraulic, Allison 4-speed, no lock-up. But I think you are right.
Perhaps my OE tach does not have the scaling
and resolution for me to see an increase in RPMs, when the CC brings the speed back up from a 1 or 1 1/2 MPH decrease from set-point.