Hi everyone
My friend has an '84 944 that won't pass emissions at idle. CO and HC's are very high, several times their standards. Loaded, the car passes with the specs right were they should be. He has a new factory cat, new O2 sensor, and new spark plugs. The AFM has never been opened, but is original.
The car runs decently, and pulls strong vacuum at idle. So far i'm thinking it could be the AFM being worn out, the DME could have a fault, or mayber the throttle position sensor?? Any ideas of how to test these or other possible culprits for problems? Thanks