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Thread: Motronic 745i Information... wiring diagrams, pinouts, etc

  1. #26
    Join Date
    Sep 2016
    Location
    barbados
    Posts
    31
    My Cars
    1985 745i bmw
    also can the speed sensor clearance be adjusted??

  2. #27
    Join Date
    Jun 2010
    Location
    TX
    Posts
    4,487
    My Cars
    1983/84/85 745i

    Thumbs up

    Voltages look good. Make sure black plug goes to the speed sensor and 'D' on the transmission.

    There are only 27 pins on the engine side, easy to test them all really with the documents I sent you. Check for simple continuity. It appears Pin 20 on the ECU is the ground signal to the FP relay. Check this with a simple test light...to make sure the ECU is outputting the correct signal. It should only output this signal during engine cranking or running.

    You may also want to bypass the ignition switch as well as the main relays. These are well known culprits for failure to start on these cars.



    Please remember, these ECUs are all 31 years old at the very newest. Solder joints fail, power transistors fail, among other items. You may just need a rebuilt ECU, luckily your coil is pulsing via Pin 1. I have a dead ECU here that does nothing. One pulses the injectors but does not trip the coil and another with a burned internal trace.
    I make E23 parts.
    09/1983 745i (stolen spring '13 around Houston, TX Achatgruen on nutria buffalo. 8481080)
    10/1984 745i
    11/1984 745i
    11/1984 735i (10:1-265/6)
    Ford, MB, and GM round out the pack.



  3. #28
    Join Date
    Sep 2016
    Location
    barbados
    Posts
    31
    My Cars
    1985 745i bmw
    I finally started the car I had to replace the darlington transistor in the computer so I'm good now u were very helpful. the injectors were sticking too so I'll service the engine next.

    it started and ran nice and quiet cool running engine
    Last edited by sius072; 05-15-2017 at 03:32 PM.

  4. #29
    Join Date
    Sep 2016
    Location
    barbados
    Posts
    31
    My Cars
    1985 745i bmw
    one question for ya, does the e23 745i 1986 have a fuel accumulator because I notice that some thing is missing in the area of the fuel filter under the car so I'm wondering what it could be, it's not the fuel pump I'm sure of that

  5. #30
    Join Date
    Jun 2010
    Location
    TX
    Posts
    4,487
    My Cars
    1983/84/85 745i

    Thumbs up

    Glad to hear you are operational again!

    Shoot me some pictures please. Depending how your vehicle was optioned, it could be one of many things under there.
    I make E23 parts.
    09/1983 745i (stolen spring '13 around Houston, TX Achatgruen on nutria buffalo. 8481080)
    10/1984 745i
    11/1984 745i
    11/1984 735i (10:1-265/6)
    Ford, MB, and GM round out the pack.



  6. #31
    Join Date
    Sep 2016
    Location
    barbados
    Posts
    31
    My Cars
    1985 745i bmw
    I'll send some pics soon also if u sell the motronic delete chips I'll buy one from ya. Also u'll have to help with the Watergate mod.

    - - - Updated - - -

    I also need some info on how to remove the headliner cover and get at the sunroof

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