sometimes I have to press the gas pedal harder & for longer with higher rpm to reach from 0-60 as quick as other times...when it acclerates faster without flooring the gas pedal, and much less hesitation and effort by the engine (lesser rpm)

Is it because the engine (or a computer) gets used to the regular city driving and records my tame driving habits, and then refuses to respond on rare occasions when I want the engine to perform? ( just asking)

 

If you have an automatic transmission it might be because you're sitting on a "flat spot", for lack of a better term, when you hammer on the accelerator.

I know from experience there are RPM ranges in my car where the acceleration is dead, due to a combination of transmission and rear end gearing.

 

Thats right. My car is auto trans. But how to explain performance variations each time I try a 0 to 60mph

One thing I may have noticed is that if I've tried to race from 0-60 a couple of times one morning, and then reach a traffic signal, then when the lights turn green, it starts taking off to a really quick 0 to 60. It makes me wonder if the engine attunes to my style of driving that morning(??)

Basically it performs well after a couple of tries, and not the first instance when I want good acceleration.

 

For the most part its probably in your head. But IIRC the computers in these things actually take lessons from the way you drive the car.

 

Stick it to the floor.

Moving thread.

 

The PCM does not "learn" your driving style. It learns how to correct the A/F ratio for various combinations of RPM and engine load, and it learns where to set the IAC motor to provide the correct air for startup. May switch between high and low octane fuel with extended use. How fast it learns to fill the correct long term corrections in all the "Cells" (a grid, based on combinations of RPM and MAP) will depend on how long you have actually operated the engine in those cells since the last time the PCM was reset. So there is an advantage to operating the engine over a wide combination of RPM and engine load to insure it fully develops the corrections in each cell. But that's it.

When you go WOT, the PCM should enter power enrichment (PE) mode. At that time, coolant temp can have an impact on how the engine performs. The PCM will set the target A/F ratio based on the coolant temp reading. High inlet air temps also seem to eliminate some timing that the PCM adds in excess of the lookup values in the spark tables.

Other problems with the engine could affect the response to the throttle... erratic TPS voltage, a leaking bellows between the MAF and the throttle body, sloppy engine and PCM grounds, etc. With an A4 and the LS1, there may also be issues with torque management.. I don't know the LS1 PCM's as well.

If you really think there is a difference, try doing some 0-60MPH runs with a stop watch, and find out if its real or imagined.

 

It's in your head.

Scenario 1: When you say you press the pedal harder and RPMs are higher to get to 60mph, sounds like you're probably in 2nd gear. The more throttle you apply, the higher RPM it will take to shift. So the engine "working harder" is b/c you're probably still in 2nd and it's howling.

Scenario 2: When you press less and seem to get to 60mph with little strain, I bet you've shifted already into 4th, and the RPMs are low to reach 60mph.

Now, which is faster?? Well Scenario 1 should be faster, but only way to know is to measure your times.

 

@ injuneer, man when I typed that I couldnt get it into words that made sense at the time, (you know those days when you have a case of "the dumb") so thats what I typed. Although my best explanation still wouldnt have been as clear as yours.

Injuneer saves the day once again!

 

These cars get moody.. -Seriously.. If I've been on the HW she just wants to MOVE afterwords.. But if I've been babying it, she doesn't want to move at all..

Sounds crazy, but it's true..

But on a mechanical note.. You have to take into account for ambient air temperature and humidity, fuel level.. etc etc.

 

Oh I really think that there's some computer hanky panky going on with the stock LS1 PCM programming as far as this subject goes.
Back when my 00 was stock, I went to the track, teched in, waited the 30 minutes, and went down the track. I always did 4 hot laps, park for 30 min. and repeat.
The first pass was always and I mean always .1 to .15 slower. After enough track trips (I usually go 14-20 times a year) to realize that this was a pattern I tried a little experiment.
After turning the last corner before the track I'd pull over and stop. Keep in mind that this is a back country road. When traffic was clear I would go WOT up to about 70 or so from a stop and then proceed to the track.
No more slow first pass it was the same as the rest. So I always thought that there was something in TM or the trans adaptives that the PCM changed under percieved hard acceleration.

 

There you go. You nailed it. I'm convinced there is something under the hood that watches you and then adjusts accordingly. Flooring it (as Injuneer suggested) doesnt help as my Z28, as most Z 28s, have a sticky rear and it just spins and wobbles...so no forward thrust that you might otherwise expect. When I'm in a mood to kill the stang thats next to me at the traffic lights, I need the take-off power on demand

 

You may want to look into a high stall torque convertor and some suspension upgrades and better tires

High stall convertors are supposed really do wonders for launching the A4 cars

 

Well, that certainly has nothing to do with the OP.

 

Maybe not, but I'm sure it would help with "his sticky rear and it just spins and wobbles" when he puts the loud pedal down to the floor