I have been trolling and searching this wonderful forum for an answer to my cold start problem.

A little history on the problem to begin with. It all started after the alternator and battery kicked the bucket, Confirmed with my multimeter. After replacing the alternator, alternator bushings, and the battery it now starts extremely rough almost as if its missing on a cylinder. I have checked the plugs and none of them are wet/wetter than each other. I cleaned the throttle body, IACV, the AMM connector, all engine grounds, and almost all vacuum hoses. I have also replaced the plugs, wires, cap, and rotor.

The hard start never happens after it is warmed up. When starting cold if i let it idle for a few minutes it is just fine. I do have a 1-2-1 code from hole 2 on the diagnostic box under the hood. Could someone provide me with some more insight on what to do? Any help is much appreciated.

 

1-2-1 indicates a funky signal to/from the AMM (I usually call it the MAF, mass air flow, but same difference). if you can find another 1989+ 240/740/940 (1990+ for turbos) you can borrow the MAF from, try swapping them, see if this goes away. older LH2.2 cars used a different MAF, you need a -016. if swapping it fixes your codes (and breaks the other), you need another one. warning: the after market budget rebuilds are often crappy and fail fast. the MAF spray cleaners seem to do as much harm as good.

the cold start symptoms sound like the ECT (engine coolant temperature) sensor is funky. this is a 2 wire temperature-variable resistance device screwed into the block below the intake manifold between cyl 2 and 3. one wire goes to the ignition control unit (ICU), the other to the engine control unit (ECU). an ohm meter on either pin to ground (with it disconnected) should read around 6000 ohms at freezing, 2300 ohms at 68F ('room temp') and 200 ohms at 212F (boiling). but, they also could be the MAF, so I dunno.

 

UPDATE: I haven't been able to locate another MAF to test yet but after cleaning a bunch of sensor connectors it is getting better. Specifically after testing and cleaning the ECT. My multimeter bit the dust so I am unable to test it right now. I'll keep updating this thread with my findings.