Hi, my ride : Jun'05 Audi A4 2.0MU. Problem : Fluctuating RPM between 600 to 1200 which is intermittent. I have changed the spark plugs, cleaned the throttle (reset it), changed battery & air filter and bleed the coolant to rid of airlock. It only got better after the airlock is removed but after 1-2 weeks, the rpm needle started fluctuating again. It usually starts to fluctuate (not when i start the car in the morning) in the mid-day when i restart the car after it has "rested" for 1-2 hrs or sometimes <1hr... & only when the air-con is turned on and either in the D or R gear (in the R gear it is more prone to happen) and when i gave the accelerator a slight push... it then fluctuates for less than 1-2mins before settling at 800.. there is no error code when i went back to the agent for test. Please advise. thanks..

 

I had the same problem its a sensor that went bad it was warranty on my car all dig around and see if i can find what the part was that they replaced.

 

Thanks!! Hope you'll be able to find the sensor that they replaced and get me out of my misery.... Thanks.....

 

Hi Ocadam, any good news for me?
problem getting worser now... thanks......

 

I have a 2005.5 and i am having the same problem. almost feels like an IAC (idle air control valve)Mine is very intermittent and does it more with the AC on.

 

amt it could be sparkplugs on you depending on how many miles u have driven

 

Yes, you seem to have exactly the same problem as me.
It stops fluctuating the moment the aircon is switched off..
Frustratingly intermittent too...
I am not familiar at all with all the sensors that could cause this and hope someone here can pinpoint to the exact sensor that needs to be replaced.. hope it does not lead to any bigger problems...
IAC - is that the Y shaped valve that is located quite close to the throttle?
I was told it can't be cleaned like the throttle but has to be replaced...
Anyway, did you manage to solve the problem yet or have you changed the IAC? thanks..

 

26,000 miles so far. Had the spark plugs replaced about 1mths ago....

 

I'm getting this issue also. RPM fluctuates a bit.. up to like 1400rpm even (on idle).. or when i shift, the RPMs go down slowly but not to the regular 800 lets say. Haven't tried the A/C (its like -20*C outside). Kinda seems like a vaccum issue, as if there was a leak.

I had barely noticed before but just figured it was the cold, or maybe when the fan went on.. I got a check engine light yesterday. Tried to check with my ebay vag cable but couldn't access the engine module. The car seems to run fine besides that.. no hesitations or anything like that.. just the RPM fluctuation. It wasn't consistent though.

Possibly drive by wire system? Will get the car scanned and probably find out soon enough

 

did u find out what the problem is?