Hi.i have a 04 audi a4 1.8t quattro 91k on the clock.The idle speed is too high about 1.2 and fluctuates to normal and then sometimes revs to 2,5 and then settles back again after a couple of seconds.I have also noticed the temp gauge is not moving and no sighn of the fan coming on.Are these problems related.My car just failed its mot due to high exhaust engine idle speed 7.3.d.2.a.. Thanks Tony

Question edited for clarity, (all the typos)!
Question moved from Miscellaneous.

Perfectly normal. The coolant and radiator cools the engine, but at idle there is no passing air to cool the manifold and exhaust. Just make sure there are no codes and that you are not running lean.

You can take it to most auto parts stores such as O'Reilly's or AutoZone and they will scan for diagnostic trouble codes (DTC) that may be set in the computer.

Engine stalls cold or RPM fluctuates at idle up and down or dies near idle.

This problem is commonly caused by a dirty automatic idle speed control valve and throttle valve but always run a OBD2 fault code as well as the cleaning procedure. Buy a can of throttle valve cleaner (do not use carburetor spray cleaner!) from NAPA or Carquest (made by CRC chemicals) and spray it into the air intake while the engine is running, use up about 1/2 the can, engine will try to stall hold the speed up, shut it down and let it soak for 30 minutes, restart and blow out the remaining fluid, shut it down and disconnect the negative battery cable for 5 Min's to reset the base idle control. If the above cleaning doesn't cure your issues you need to have the computer controlled automatic idle speed control system diagnosed and repaired by a dealer or electronic engine control repair shop.

A big vacuum leak will do this it can be from a open PCV valve sticking open EGR valve to a sticking a IAC (idle air control valve) sticking open. You basically have something get stuck and closing.

The oil pressure guage will fluctuate with engine RPM. At idle it should be approximately 20 lbs./sq.in, at high revs about 50-60 lbs./sq.in. Hope this helps any concerns you may have. Good luck!

i would check the throttle butterfly for a carbon build up that may keep it from closing completely. have seen this cause stalling when returning to idle rpm. Best to try to remove and clean from both sides to get good results.this is just one of many possible problems. Hope it helps if so please let me know with a reply and good luck

i have a 2001 Audi A6 quattro 95,000 miles when i change gear the car seems to over rev or keep reving when i put my foot on the clutch for a split second chould you tell me why is this

1. vacuum leak; check all rubber hoses for cracks
2. idle control valve; remove and clean with carb cleaner

mcdevito75 here, A vibration while idleing is not really normal, a rough idle could be many things, wrong octane gas, dirty gas filter, dirty smog controls. Have your local shop take a look for you.

HI,AT WHAT SPEED DID THIS HAPPEN,IF AT IDLE OR VERY LOW SPEED,HAVE A NEW BELT FITTED IF IT RUNS NORMALLY YOU ARE LUCKY,IF IT RUN ROUGH WITH BAD MISFIRE OR NOT STARTING AT ALL THE VALVES ARE BENT,PLEASE LET ME KNOW,ANDY.