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Dave and I have been working on this problem on the board for a while now and I am sure many of you are board with this,so here is some additional boring testing.My 740 with b234 has had a idle trim code 232 for some time,code 232 doesn't indicate rich or lean;(that would be nice)just that the mixture is incorrect and the ecm has compensated as much as possible.Anyways after exhaustive testing and looking for vacuum leaks and setting and cleaning the throttle plate,checking fuel pressure,many other tests.I then used an adjustable resistor(pot)and jumped on end to a good ground and the other to the coolant temp sensor plug on the harness side going to the fuel system ecm,I have done this with honda motorcycles and have good success in determining if the engine is rich or lean(no o2 on these types).The b234 wanted more injection duration to smooth out the chunky idle indicating a lean condition,when I went back to the base line of 200 ohms(190d temp) the engine went back to its old chunky idle.At 2.3k ohms(76d temp) the engine idled like a dream nice and smooth like before the alternator went south years ago,possibly related,I don't have a exhaust gas analyzer to confirm the fact the the mixture is lean so this works for now.To require this much duration change is it possible that a large enough vacuum leak is present to make the engine want more fuel or is the fuel ecm just not providing the proper duration?
Also when I performed function tests in controll function #2 for the thottle body switch test I got code 332 instead of code 322(there is no 332 in this test mode)maybee this indicates more internal problems with the ecu.Is there some place that checks full function of an ecm unit?
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