Today I was driving about 75-80 and when I downshifted to 4th to accelerate, the car hesitated for a second and then took off. It also did it when I went from 5th to 3rd. It only happened twice and after that when I downshifted, the car accelerated normally. I was not driving that long of a distance or at a constant speed when I the delay happened, so I don't think it was one of the TSBs. Does anyone know what the delay could have been?

 

Although there's a TSB out there for the fuel pump, mine does it on rare occasions and I suspect it's the Traction Control System. Others have said that my symptoms and the one you describe aren't fuel pump related. Mine hasn't done it when I've had the TCS off. A few months back I had the TCS on, mashed it and it hesitated. At the same time I saw the TCS symbol on the speedometer light up.

 

I had the t/c off. It may have been a little water in the gas.

 

Try running some Techron in the next fillup, clean the MAF, and throttle body.

 

There's also 2 other theories that seem to arise in these discussions.

1. the Fuel Pump TSB which is aimed at '05's and '06's but some '07 owners claimed the TSB "fix" worked for them; others not
2. the drive-by-wire system is prone to "delays"

And another one that came to mind is throttle lag which is fixed with a custom tune. But a lot of people reporrting the problem HAVE custom tunes.

It's one of life's little mysteries...

 

Problem solved! Cleaned the TB and that made a difference in sound and performance. Even at idle my RPMS tend to stay a little higher. As far as sound, one of my co-workers said my car sounds meaner now.

 

gman,
what did you use to clean it?

 

Valvoline carb and choke cleaner.