Re: 92 740 wagon B230 turbo LH Jetronic.... Ok...I finally ran my own tests today. Spark is strong to all 4 cylinders. Fuel pressure in the rail is 42 when cranking. I lifted the entire fuel rail/injectors up and watched them while cranking. They are not leaking fuel. When cranked they are spraying a LOT of fuel, I think it is way too much, from the first shot on. It remains the same large volume no matter how long you crank. So I figured out what is happening. On the first attempt to start car, it "fires" like it is going to start for about one second, then nothing--- because the cylinders are being flooded with gas. This is why it will not fire again at all unless the car sits for a day. Whatever it is, it was making the car run rich for a couple of months or so. Ocasionally during this time, the defect would get suddenly worse, and the injectors would go to max, flooding the engine...causing it to die while driving. I have a strong supspicion it is a bad or missing sensor input, probably not the ECM itself that is causing this. But....the ECM is not setting any codes to show what fuel control component is bad. THe crummy 82-88 740 Haynes manual I have says there are six inputs to the ECM that control fuel delivery/mixture: AMM, ECT, 02 sensor, plus an air control valve and transmission and charge overpressure switch.
Problem is, I don't have specific info on how to test these components. Is there perhaps one component that, if bad, would make the injectors go full rich on cranking?
I think that when a car *runs* rich, most likely thing is a bad O2 sensor...but doesn't the control system ignore the O2 sensor until the engine is up to operating temp? That would mean that it is not the culprit in this case.
Thanks, Geronimo