[s-cars] Re: Emissions Test Failure

[William Noland]

Gary -
Have you checked the O2 Sensor?  I'd agree that you're running rich.
 The ECU will default to its last mixture setting before the sensor goes
out, if it, or the wiring, has gone bad. One other possibility would be
a bad thermostat.  If you're water temp gauge isn't consistently getting
to the first bold hash mark, your thermostat may be toast.  If the motor
isn't warming up properly, it could be running on the rich side.  I was
experiencing a rotten egg (rich idle) smell, which was drastically
reduced, after replacing the thermostat.  Temp gauge shows the motor
finally warming up properly now.

Bill Noland

>
>My '92 S4 failed  the emissions test, in particular the hydrocarbons at idl=
>e were very high. All other readings (CO,CO2) were normal at idle and at 25=
>00rpm. The car has had a stumble off idle recently, so I suspect it may be =
>running rich at idle. I checked the throttle switch per the instructions on=
> S. Mockry's site, looked for vacuum leaks, and pulled the ECU codes, all t=
>o no avail.
>