1994 940 Rex-Regina intermittent check engine lite and smog issues
 

Hello everyone, I am in need of some advice regarding my recently purchased 1994 940 with Rex-Regina fuel/ignition system. The car is in amazingly good shape for its year (I live near San Diego) with only 137,000 miles on the odometer; a very sweet auto for sure. However, the check engine lite comes on intermittently and although the engine runs like a top, it will not pass California smog. HCs= perfect. CO= perfect. NOX= way high. Since the car does not have an EGR system, we are thinking that the high combustion chamber temp which is causing the high NOX is due to a lean running condition. Catalytic converter is a few years old according to the records. O2 sensor very recent. Engine intake air temperature sensor (which sits where the Bosch air mass meters sit at the intake air hose) is new. Tune-up fresh. The only running issue that I notice is a very slight stumble at cold start up for about 5-10 seconds, then it evens out perfectly. Something else that might be related is a faulty fuel gauge; I understand that this system has only one fuel pump in the tank and is mounted with the fuel gauge assembly. Long shot, but possibly affecting the condition. Also, unfortunately, I cannot retrieve fault codes from the diagnostic socket. When I initiate the retrieval process the red light begins to flash continuously, so no help there. I know these systems can be a bit glitchy. Any one have any experience which would help me out; I would greatly appreciate it. Thanks.