Have a 03 A6 3.0 Avant... on occasion and it seems this only does this when the tank goes below 1/4 I have idle/surge issues. It acts like the ICV is not functioning and will surge back and forth between 200 and 1200. After a bit of the surging my ESP light will come on and the tranny will shift harder than normal and will "clunk" from Park to Drive... Now that I have noticed the gas level connection, I will fill the tank after this happens and drive on the highway for a bit and it all clears up and functions normally after maybe 10-15 miles. I had a coil go bad a while back and at first I thought this may be the case, but it's not acting like the other one that went bad. What is also interesting is that all this started when I put new tires on the car about a month ago. The tires were just a touch bigger.. From 215/55R-16 to 215/60R-16. Any input would be great... thanks!!


Oh and it seems my power steering is real noisy when it's colder out. Is this normal or is the pump getting weak?

 

You must have a haunted car one could say.


Quattro?

Mileage?

Any DTC?

 

Quattro and it has 90k on it. I have not pulled codes yet.

 

For the problem to be tire change related, it may be that the process involved some damage to something under the car, such as a fuel line, EVAP line, a tranny cable or similar. I would start by being sure the fuel supply or return line is not damaged.

 

Solved... Well.. looks like a intermittent misfire on cylinder 1.. popped in a new coil for 30 bux.. seemed to solve it. What's weird is how this misfire also affected the esp and it would disable during a times when the coil would go out..

 

Actually not solved and then solved again.. the car ran fine for a day after putting in cylinder 1 coil and then started acting funny again. I have access to http://www.shopkey5.com/ and one of the trouble shooting steps was to verify there were no vacuum and or air leaks.. So I was checking and when I took the back plastic cover off the vacuum/intake stuff I noticed that the main intake hose had come loose from the intake at the motor.. SO I was sucking air from there instead of through the filter etc..all the time bypassing the mass air flow sensor etc.. I popped the hose on and all the problems are gone..