Hey guys and gals. I'm trying to track down the cause of a fast idle of around 1100rpm. So far I have eliminated the extra air valve, throttle bodies and linkage and vacuum leaks. My idle adjustment is turned all the way in so I have no more adjustment left there. My knowledge of the V12 is limited so I'm wondering if I could be missing a sensor or some other component that could cause this. Forgot to mention I also re-torqued all the intake manifolds.
Thanks in advance for any help you can offer.

John
1990 XJS

 

Hi John,have you checked the coolant temp sensor(beside the left thermostat) and the air temp sensor(left air filter housing trumpet)
Good luck
Les
88 1/2XJ-S

 

Not yet but I'll check them next.
Thank you......

 

Culprit was the extra air valve. Cleaned, lubed and reinstalled.