Idle speed

[Laurie]

Hi, I recently bought a 2003 RS saloon (64000 miles) which has just developed a fault of idling too quickly (up to 1500 rpm). It's recently been serviced with new plugs, filters and air mass sensors and the garage (a VAG independent) seems flummoxed by the error. The fault developed almost straight after they resealed the sump to cure a small oil leak. The only clue seems to be an error code related to a engine mounting vibration sensor, which shows up as a sporadic fault. Anyone come across this problem before? if so, would be great to hear what the solution is!

[grizz]

I would say the air box is not seated and you've got a air leak

[vinny]

hey laurie, that fault with the engine mount is related to torque. dont think it will affect the idle though, but i know on the A8's, there is a factory mod where a blank off harness is sold to plug into the existing harness, to keep the ecu happy - i think these mountings are a little over-sensitive...
but like grizz says, maybe check that airbox for correct seating and vacuum/brake booster lines for leaks.....

[Laurie]

hey laurie, that fault with the engine mount is related to torque. dont think it will affect the idle though, but i know on the A8's, there is a factory mod where a blank off harness is sold to plug into the existing harness, to keep the ecu happy - i think these mountings are a little over-sensitive...
but like grizz says, maybe check that airbox for correct seating and vacuum/brake booster lines for leaks.....

Thanks, Vinny and Grizz. both responses are really helpful. Bosche have told my garage that the rubber seals on the airflow meters can deteriorate and cause an air leak. My meters were recently replaced, but seals weren't in stock. They will be replaced next week. However, the problem started before the meters were replaced (that's why they were replaced), so I'll have to wait and see whether it does the trick.
Sounds like the engine mounting fault is a red herring, although my garage say that a faulty knock sensor can cause the engine idle speed to increase by foolling the ECU into thinking the engine is about to stall.

[vinny]

hey laurie, maybe the engine mount fault is a red herring... ive done yet another rs6 at the shop with high idling issues - replaced the following: seals where airmass goes into intake tubes, o-rings where airmass seals in airbox, ALL vacuum hoses - problem solved!!!!! car goes like a rocket!!!! dont replace just the seals on the intake tubes - do all as listed above