[s-cars] Rough Idle on startup, Rich exhaust, warms up and fine...

[Nic Bode]

Gentleman,

 

93 S4 with 109K on the clock. Start up on cold, either overnight or after a
day of sitting the parking garage at work. Runs rough like on 4 cyl and
strong unburnt fuel smell from exhaust. Let it idle like that for 5 minutes
maybe and something changes and it idles fine, runs fine. My thoughts are
obviously it is temp related but what? Coolant? Oil? I really think coolant
related but I don't know of a sensor that would read either coolant or oil
temp and feed that info to the ECU to tell it to run rough like that when
cold. Am I looking at another Multi Function Coolant Temp switch under the
intake replacement? 

Just want to narrow down my buy a switch and replace repair bill. I know I
could run all kinds of temp and ohm readings from various spots but really
don't have that kind of time or money for the indy to spend that time under
the hood with all the probes. 

 

Thanks