[s-cars] rough idle

[Martin Baggenstos]

Hello everyone,

  I am hoping someone might have some insight into why I am getting a rough
idle on my 1995 S6. My car has most of the RS2 mods (MRC chip, turbo, FMIC,
manifold, etc) When at idle, the engine runs rough and it is worst if the AC
is off and, after about 10 seconds, the check engine light will come on, but
goes off if I hit the gas. The car will not stall but just runs rough at
idle. The only things I have change recently is a bad HO coil from the 034
kit which was giving me problems more under boost. I also recently replaced
the MAF to turbo hose with the silicone 034 hose for my Rs2 turbo and have
read some some reports that large silicone MAF to turbo hoses could cause a
rough idle, but I believe that this one is designed for my turbo. Could it
be related to a bad O2 sensor? I also have a digital A/F monitor and at idle
it reads numbers as low as 10-15 when this probelm occurs leading me to
believe that the car is running very lean.

Martin