Detonator

URGENT HELP NEEDED HERE !!

My 2003 A4 3.0 QT MT6 has suddenly developed this really rough idle/drive and I can't seem to find what is causing it.

Car has 74k miles (timing belt has NOT been replaced yet).

I took it today to get an oil change & Flush at a local Audi/VW shop hoping the new oil would make the issue go away but no luck.

They checked out the car and could not find the problem, they checked for codes - and not a single error. That is when my gut started to tie into a knot (fearing the possible worst) as their only guess could be a malfunctioning pulley causing the rough idle. Could this be ?? Has anyone had an issue like this ??

A little more about the problem - this is not the FIRST time this rough idle shows up, it has happened a 2 times before and the car would rough idle for like 2 days and THEN go back to NORMAL. Also about all 3 times the issue has occurred it has showed up after spirited driving on the highway at 80-90mph - once I would get OFF I would notice the idle had changed ... It has been more than 8 days now and it still persist, now Im fearing the worst.

Again the car gives NO CODES, also the ENGINE MOUNTS checked out ok.

WTF could it be ??

ajg617

Ditto here. Just got my A6 Avant 3.0 back from Audi after a recall fix on the fuel tank overflow valve. Drove it home and it smelled like rubber and then plastic burning in the engine compartment. Now it's running on 4 or 5 cylinders at all speeds. No codes either. Still stinks when hot. Visually, can't find anything touching the exhaust. Anyone have any suggestions before I have it towed to Audi?

THanks

S4_Cinci (I S'edTFA)

(intake air temperature) that can give slightly incorrect readings. You can buy a spray can of MAF cleaner at most any auto parts store - just make sure it says it is safe for plastics. Use it on the IAT sensor as well. The throttle body cleaning is more complicated, check out the Tech Articles. BTW, I am assuming that the 3.0L 30V is bery similar to the 2.8L 30V in giving these suggestions. Not every small issue will throw a code. Could also be an issue with the PCV system (commonly called a suck pump in these forums as the system is quite different from Detroit iron style PVC rattle valve). If you suck up a lot of vaporized oil from the spirited driving, it can clog the system and give problems.

Doubt it is anything to do with a pulley.

DaveInSaltLake

there are a number of devices it runs and that's a quick way to eliminate problems related to too much friction in any of those. for instance, I once bought a A4 that had a seized AC compressor that created so much friction on the serp belt that the car wouldn't even start. pulled the serp belt and the car fired right up.

don't take it for a run on the freeway or anything with the belt off, but idle it in your garage or drive it around the block to test.