1984 245 wagon failed HC and CO on emissions test. NOX passed and was very low.
I have tuned car and it runs great. Things I have done include replaced cap and rotor, replaced thermostat, replaced coolant temp sensor, fixed any/all vacuum leaks, verified TPS is ok, set idle speed, and set timing. The car starts and runs fine; however, it must be running rich because of high HC and CO. One problem I have is that the idle air bypass valve doesn't seem to be working, because the car stays at a fast idle even if I ground the blue wire in the fender connector that you are supposed to ground in order to set the base idle speed. I had to actually block off the bypass in order to check timing at 750 rpm. So the non-working idle bypass valve indicates to me that there may still be a problem with the coolant temp sensor and this is also why the ECU is keeping the mixture richened up even after the engine is hot. Anyone have any other ideas?