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Thread: M20 Throttle/revving issues

  1. #1
    Join Date
    Aug 2009
    Location
    Atlanta, GA
    Posts
    158
    My Cars
    '72 tii, '91 318i Sedan

    M20 Throttle/revving issues

    Im having an issue while trying to get my m20 swapped 2002 drivable. Heres the story-

    First got the car running, only ran on 2 cylinders, but revved freely, idled ok considering. Figured out 4 injectors were not triggering. Pulled the intake to replace them, which i now realize was probably not required.

    Put it all back together, car fires right up and is clearly running on all cylinders, revs freely and idle a touch high but steady, but I had the idle control valve in backwards (see orientation in 1st video).
    I flipped the ICV around the proper way (2nd video), (not 100% sure i didnt mess with other stuff) and ever since the motor will not rev higher than 2k, and even if i floor it, it holds 2k for a second, drops to idle for a second, and revs back up - clearly something electronic is not happy.

    Things Ive tried:
    Unplug AFM - car runs rough and/or dies

    Unplug ICV - idle rises to 2k, but revs freely

    Unplug Throttle sensor- nothing happens, still has the intermittent rev, when I plug it back in the revs drop slightly

    Unplug Evap solenoid- nothing happens

    Unplug ecu/battery for awhile- no difference


    Now on to the interesting part:

    My friend has a e30 with the same motor and was kind enough to let me test the above parts(other than ecu) from his car to see if it fixed it, however I didn't notice any difference as I cycled his parts through.
    I should note that his car is not running due to what sounds like a similar issue, so who knows if any of the parts are good/better than mine.

    Whos gonna save the day?

    Video 1 , normal running and revving
    https://youtu.be/mu5agU-QegI

    Video 2, current issue
    https://youtu.be/4X38ZT_Dt6U




    Sent from my iPhone using Tapatalk
    Last edited by meintii; 09-07-2017 at 08:21 PM.

  2. #2
    Join Date
    Feb 2015
    Location
    Maryland
    Posts
    1,221
    My Cars
    325ix, 325ix, 540i
    Remove the ICV, get a penny, drill a small hole in it, and then put it in the intake boot hole. Hose clamp it in place.

    Can you rev past 2000?
    If your e30 runs bad, switch to Megasquirt first. Then try new spark plugs, cap and rotor, wires, oxygen sensor, crank shaft position sensor, coolant temp sensor, air flow meter, idle control valve, throttle position sensor, digital motor electronics unit, harmonic balancer, fuel injectors, engine harness...

  3. #3
    Join Date
    Jun 2021
    Location
    Usa
    Posts
    2
    My Cars
    Yah I'll take them all
    Did you ever figure this out?

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