Folks,

2002 S4 Avant, 6 Sp with GIAC software, 101k miles. I have a misfire that I'm having difficulty diagnosing. It's not leaving any traces- no CEL/DTC's, and the VAG-COM didn't pull any codes.

I just did a tune up (plugs, air filter, fuel filter, general cleanup). The plugs that came out were uniform in color and completely clean- no oil fouling. The stock breather hose was just replaced with a cold-weather version (I was having difficulty in winter with freeze-up).

The misfire only occurs at light load (30% throttle or so). It tends to be a morning thing when the air is slightly cooler. It does not happen at all while on cruise control. I monitored the TPS with the VAG-COM and the readout looked smooth and clean, though I do reach 100% before the pedal hits its stop. I vaguely remember reading about that being typical, however.

Any suggestions? Is there anything I can look at/monitor with the VAG-COM? If so, I'll need specifics- I'm brand new to the thing (it's borrowed, anyway).

Many thanks in advance.

Regards,
Rob

 

id recheck your plugs and/or make sure the coil packs are on properly and plugged up all the way.. it could be something simple.. maybe a plug was dropped and closed the gap and thats easy to miss....

 

Thank you for the reply. I should have been clearer- I did the tuneup in response to the problem, so it has performed the same way on two sets of identical plugs.

The plugs are stock NGK's.