Hi all,

I am desperate need of help/opinions! I have a '99 Audi A4 2.8 L automatic, and have been having trouble with my acceleration.

Back story: A few months ago, I accidently left a light on overnight. The next morning, the battery was dead. I didn't have time to jump it because I had to leave the city for a month, so basically my car was sitting in a garage for a month (I know--bad). When I got back, I tried to jump it, but by then the battery was too dead. Luckily I had a warranty on the battery, so I brought it to the store and they re-charged it. All this seemed to work--my car started with the fully charged battery. However, the engine would start, then suddenly die. I tried a few times, then finally the engine started, but sounded very weak.

Now, my car has been starting but not without the following problems:

I can't seem to accelerate properly--it takes forever. I slam the gas pedal and the car slowly moves to 20mph and lingers, around 1000-2000 rpm. I then feel a shuddering/shaking sound/motion as the the car seems to bounce between trying to get past the 1-2k rpm. This lasts for 5-10 seconds! Finally it gets past, after lurching forward suddenly. This entire process takes forever to accelerate to any speed higher than 20 mph. Luckily I am able to get to 60 mph on the highway after a LONG period of acceleration (I really feel bad for traffic behind me). However the car doesn't seem to want to go past 60.

**I found out today whenever I have the studdering/shaking engine problem, if I switch to triptonic and lower the gear, the car starts accelerating almost normally. Basically if I am at a stop light and I try to start, if I leave it on automatic it starts shaking around 20 mph, then slowly accelerates. However, if I am in triptonic mode and I let the car stay in 1st gear for awhile, the shaking sound becomes very minimal (~1 sec), then accelerates pretty normally and I can change gears. Despite the latter improvement, I would rather not drive like this.

**another important thing: when I am idling, especially for a long period of time at a traffic light, my engine will randomly die and I have to restart the engine!

One last thing (not sure if it's related): my AC unit is not cold at all when I am at low speed. However once I am able to get past 50-60mph it starts working perfectly. Could this be related?

I have brought my car to two garages. The first was an oil change that came with filter changes etc. and a free inspection. Upon the inspection, the mechanic told me the computer diagnostic revealed an error code. I don't have it with me now, but will post it later--it had to do with the throttle. After researching online I found that others had the same symptoms as me with this code and they recommended cleaning the throttle body. I then went to another mechanic this morning to have it done (I know it's a minor job, but I am not experienced with cars, so didn't feel comfortable doing it). He said he did his best to clean it and also found that the air filters were dirty, so he cleaned them for me. He also said he added fuel injection fluid (I forget why?) Unfortunately the acceleration problem hasn't gotten better and I really don't know what to do. Does anybody have any advice or has gone through the same thing? Thank you so much guys!

 

We're going to need the codes to start troubleshooting - there are way too many possible issues to blindly start guessing. If you can, go to Advance Auto for a free ECU scan and you get the codes that way. You may have new ones now, ^^^so that updated list would help a lot.

 

Most likely the throttle body needs to be calibrated, I've only been successful through vagcom. My car would just barely run and was spitting black smoke after my battery was dead for a couple of days, after a calibration it ran perfect.

From ross-tech: