I'm at a loss here and was hoping someone could shed some light on what's going on.

My girlfriend has an '04 A4 3.0 Auto tranny with 14x,xxx miles on it and has recently been experiencing some issues.

A few weeks ago the traction control light (Triangle with circle arrow around it) had turned on in the dash but the car seemingly drove just as it always has at all speed from 0-80mph. This light turned off by itself later on in the day, then came back on about a week later, this time with issues.

The car will hesitate upon acceleration with violent jerking (Imagine not giving a manual tranny enough throttle), and sometimes will stall out, other times will jerk and slowly accelerate. The light will randomly go off and the car will drive flawlessly until it turns on again where it drives like a teen girl driving a manual for the 1st time.

I only have 2 guesses as what this could be.

1) Torque converter

2) Since the traction light is on, maybe the sensor is going bad and it's messing with the transmission upon acceleration thinking the wheels are spinning?

What do you guys think? Any help is appreciated!


EDIT: There are no mods on this car, the most recent change was replacing the MAF sensor a few days ago. Also, there has yet to be a CEL thrown, and no codes when scanned.

 

A common reason for the ESP light to come on is the failure of the brake light switch which is mounted under the brake pedal. The ESP light has popped up then cleared on its own a few times over the years on my 02 A4 3.0 MT, but until last week it's been so seldom I haven't done anything about it. Now it's happening more often so I ordered a new switch which should arrive in a couple days. A bad brake light switch wouldn't explain why your car was performing so poorly, unless cars with automatic transmissions handle the fault a lot differently than cars with manual transmissions do.

Also, even though no CEL came up when the ESP came on, when I scanned my car I did see an entry for the bad brake light switch.

 

I don't think it's the switch based solely on how it's driving. Maybe the MAF that I replaced it with, though new, was a faulty one.

 

A bad MAF would likely explain why your car is performing poorly, but I don't see how it could cause the ESP light to come on, but then I'm no master mechanic. Perhaps you have multiple problems - bad MAF and bad brake light switch.

Also, if your MAF is bad, I would think it would throw a code.