I have a 2004 Audi A4 3.0 Quattro ... After the new a/c compressor was added, my car has been having trouble starting. It will turn over, but takes at least 10 minutes and finally it turns on. Which thereafter the EPC light comes on. It will remain on till I turn it off and restart. When I restart the car, the EPC light will turn off. The check engine light is always on, due to my torque, so the only light that is concerning me is the EPC and the fact it only comes on after my car decides to start. I never had this trouble before with the car starting till after the repair shop added the 2nd a/c compressor, which they were not too happy about doing since they just added one a year ago. I know the EPC deals with something about throttle... I don't understand what that means..but I am hoping someone might have some answers. I can't keep affording to take it to a mechanic, especially the only one in town that is not happy with me nor me with them.

 

Theres a possibility that it could be the Throttle position Sensor. If you do the work on your care yourself, I would clean out the MAF Sensor, and remove the Throttle Body and clean it out. Is your throttle cable or electronically controlled?

 

I don't even know what you mean all I know is that it doesn't start .. it keeps trying to start by turning over, it takes about 10 minutes of doing that to do that and finally the car does start and when it does the EPC pops up, but then I'll turn the car off and turn it back on and EPC is gone.

 

If you have your mechanic working on your car, it might be confusing to understand. I'm just giving out my suggestion on what I think it might be, or the causes of it. So it turns over but doesn't start immediately, The throttle position sensor is a sensor that detects the angle of the throttle during start up and acceleration, if that sensor is at fault, it could be throwing off a wrong reading to the computer that the throttle isn't open enough to allow the proper air into the cylinder for the right fuel/air mixture. So, throttle position sensor might be the cause.