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Thread: Need help after engine swap! Car runs terrible

  1. #1
    Join Date
    Apr 2002
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    Charlotte, NC
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    09 335i, 17 Jeep GC

    Need help after engine swap! Car runs terrible

    So i just completed swapping an 89 325i motor into my 85 325e. The car cranks right up every time. The problem is tha it has NO power at all. It will start and idle OK but as soon as it goes under any load at all it feels as if it is running on about 3 cylinders. Out of gear if you rev the motor the engine shakes a lot, its not smooth at all. Idle is smooth though and all cylinders hit at idle. Before swapping the motor I adjusted the valves, replaced all seals/gaskets, timing belt, H20 pump, cap, rotor, and spark plugs.

    I have checked fuel pressure and put fresh gas in the car. Fuel pressure is showing up around ~38 PSI, 45 if you unplug the vac hose going to the FPR. IT is able to maintain this when reving the motor.

    I have checked resistance on the Coolant Temp Sensor, it is in spec on the ohm meter.

    One odd thing, if you unplug the AFM it will idle smooth and REV smooth if you increase the throttle very slowly, much smoother than if the afm attached. I am leaning towards a faulty AFM but dont have one to swap at the moment to test.

    What is left that I can test to find the fault with out just throwing money at the car and blindly swapping parts?

    Any help is appreciated

  2. #2
    Join Date
    Oct 2003
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    Santa Clarita, CA
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    10,161
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    E30 Turbo
    When you did the swap did you use ALL of the 325i parts? AFM, FPR, injectors, wiring, ECU?
    BimmerHeads
    Classic BMW Specialists
    Santa Clarita, CA

    www.BimmerHeads.com


  3. #3
    Join Date
    Apr 2002
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    09 335i, 17 Jeep GC
    Yup, had the car gutted down to the shell, everything that went in is from the 89. Everything seems to work, also swapped ECU and it ran about the same.

  4. #4
    Join Date
    Dec 2004
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    Huntsville, AL
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    87 325is
    With those symptoms and knowing that the fuel pressure is okay I think I'd suspect the AFM or engine harness.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  5. #5
    Join Date
    Apr 2002
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    09 335i, 17 Jeep GC
    What part of the engine harness should check out? I have checked the plug for the injector rail as well as pulled the boot back on each connector and all seems ok. I guess the next step will be to swap the AFM and see what happens.

    I have also had a suggestion to try swapping the ignition coil, what are your thoughts there? Could weak spark cause similar issues?

  6. #6
    Join Date
    Jan 2010
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    Tampa, FL
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    '01 540i/6, '06 R1200ST
    Are you sure all the connectors are in place? Sounds like an electrical issue. I agree, check the wiring harness.

  7. #7
    Join Date
    Dec 2004
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    Quote Originally Posted by Andrew9682 View Post
    What part of the engine harness should check out? I have checked the plug for the injector rail as well as pulled the boot back on each connector and all seems ok. I guess the next step will be to swap the AFM and see what happens.

    I have also had a suggestion to try swapping the ignition coil, what are your thoughts there? Could weak spark cause similar issues?
    Engine harness problems can be subtle and hard to find. If continuity checks from the DME connector pins to the AFM pins don't indicate a problem, you still won't know if the harness is good. I'd eliminate the other possibility by swapping in a good AFM and if that doesn't help I'd change the harness.
    The car makes it possible, but the driver makes it happen.
    Jim Levie, Huntsville, AL

  8. #8
    Join Date
    Apr 2002
    Location
    Charlotte, NC
    Posts
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    09 335i, 17 Jeep GC
    I double checked all connectors were in the right place, checked the connector it self to make sure there was no corrosion and all pins were present. I am including some pictures to make the tread a little more interesting, as you can tell the AFM has been apart before, who knows what was done to it. I am about to head to the pull-a-part to see what i can find.












    Update! The issue has been resolved. After swapping the ECU, Coil, AFM, Coolant Temp Sensor, Checking timing, and Distributor Cap the problem remained. Then we pulled the fuel rail and injectors out, dirt brown gas poured out of the FPR, all the injectors were full of crap (rust?). Swapped in a new fuel rail/injectors and now she flies. Just wanted to let everyone know the resolution and thanks all for the assistance.
    Last edited by Andrew9682; 02-25-2012 at 08:41 PM. Reason: Automerged Doublepost

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