[Thymeclock]

Originally Posted by katiep

I've noticed my car shifting late also, just like yours, but I wasn't car-wise enough to realize this during the years my car was under warranty Y'all know how much it might be for them to replace the accelerator pedal assembly? Thymeclock, did you see an overall gain in mpg?

We can't assume that there is any connection between the accelerator pedal being faulty and it shifting late. Before they replaced the pedal the shifts felt murky, or ill-defined. After replacement the shifts feel more solid and well-defined, much clearer as you watch the tachometer. The shift points are determined by the TCM, much more than by the gas pedal. No, it didn't improve the MPG at all.

Do you think using the "hold" button would make a difference? I haven't had a chance to play with it, but I don't *think* it would really help with this particular problem, since it seems that you have to have already shifted up to a certain gear to "hold" it there.

No, the hold button doesn't function that way. It was designed for use in snow or mud to provide better traction. It is for when you want it to remain in first gear without revving into a higher gear; otherwise it might upshift due to your wheels spinning. Beside which the torque converter lockup is not really an actual gear. TC lockup is a more direct coupling of the transmission with less slippage than the amount that normally occurs in the lower gears. It feels and acts like a shift, but it really isn't. When the car is not in full lockup mode the transmission isn't really fully engaged - which is why we call automatic transmissions "slushboxes". All traditional automatics are programmed to fall out of TC lockup below a certain speed (in this case it seems to be at 40 MPH). The real problem is that it won't enter lockup until about 45.

What totally bites about all this is that mine is a 2004, and if yours is a 2009, it's like Chevy totally ignored this issue! Surely they were/are aware???? Surely it would've been a quick fix in the assembly process? =/

It appears they probably used the same lousy programming of the TCM for all the cars they make. When the dealer was replacing the gas pedal they provided me with a loaner car, which was a an HHR. The shift points were the same. Actually, they could redesign and change the programming of the module as it does run on software. But why should they? They don't want to improve the car you've got, they only want you to buy a new one. The only things a car manufacturer is concerned with are avoidance of lawsuits from things that could be safety related. And GM was/is bankrupt, to boot.

Actually the delayed shift points give a slight increase in acceleration. Unfortunately, it also results in reduced FE. If the shift points were lower, the car would have comparatively more sluggish performance, and most people don't want to buy a car that can't seem to get out of its own way.