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Crank-no start-E30Motronic 1.0 M20 1987 325ix

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    Crank-no start-E30Motronic 1.0 M20 1987 325ix

    Hey all,
    I’ve done my best to get through all of the troubleshooting guides and still can’t get my e30 to start so I’m looking for help.

    The Situation:
    Died when I came to a stop, never able to restart after that. A strange thing had happened before that drive: when I was driving out of my driveway, I realized that the car (manual) would just die if it was put into gear and the door was open. I tested this twice to be sure it wasn’t a fluke, as i was able to put the car into gear fine when the door was closed. A safety feature, or a clue?

    Recent Work:
    -Timing belt + water pump, ran fine following this but seemed to be starting a little harder (did not replace distributor)
    -Rear brake lines replaced and bled - also ran fine after this but then died the next day.

    Tests completed:
    -Green wire @ coil, 12V with ignition on.
    -fusable link in trunk seemed good, I didn’t unwrap the shrink wrap because it looked pristine
    -3 pin connector under dashboard looks to be in good shape with minimal corrosion.
    -Coil terminal resistance is around 1ohm
    -Coil to king lead resistance is around 5k ohm or so but I don’t remember exactly
    -distributor cover and rotor removed, were heavily corroded so I sanded down the corrosion and reinstalled
    -Fuel pump runs when car is cranking (can hear, and also can hear when jumpering the relay)
    -Main relay jumpered, still would not run
    -With ignition on, ICV buzzes
    -No spark tested both at ignition coil and at distributor HT leads
    -Both crank position sensors test at 950 ohms
    -Continuity to dme tested good for CPS sensors
    -When spark plugs were pulled, they were wet with what seemed like gasoline, so I think fuel is getting to the cylinders.

    What am I missing here? What are some good next steps for troubleshooting?

    #2
    I know you've already run through some of these tests but I attached two very thorough guides and a pinout of the DME for reference. Off the bat it sounds spark-related. Have you taken a plug out and put it up against something metal to see if it fires while cranking?

    Not sure how the door open would affect anything, the only thing that would trigger is the light switch and that doesn't share any circuits with the functionality of the car. If you're worried about a short in the lighting circuit yank fuse number 27 to take the light switch out of the equation. Speaking of fuses - another thing to check is all your fuses, always annoying but worth a shot.


    "It wouldn't be there if it wasn't..." - Milton Berle

    1988 325iS - M20

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      #3
      Yes, I did pull a plug. Also checked all the fuses.. I tried connecting it to both the HT leads from the distributor, and the main lead from the coil itself. I verified 12V at coil both during cranking and in run, and also did the screwdriver stethoscope trick to see if the injectors were firing (they seem to be ticking pretty loudly and can be heard without a screwdriver next to them).

      I also today verified continuity from the coil - terminal to the correct ECU pin. I also double checked the coil resistances, and they line up with everything I’m seeing online.

      At this point I’m somewhat at a loss, thinking it could either be the ecu or the coil. I took the ecu mostly apart today and didn’t see anything obvious but I need a torx bit to see the bottom of it where the connector connects.

      Seems strange to me that the ICV, injectors, and fuel pump seems to be working but the ignition is not at all. I have a new coil on the way, and I’ll take the ecu apart and check for connector continuity there.

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        #4
        Update: The coil was bad. Replaced it and the car fired right up!

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