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Thread: Need Your Opinions on this Injector/Wiring Diagnosis

  1. #1
    Join Date
    Jan 2023
    Location
    Niagara, Ontario, Canada
    Posts
    4
    My Cars
    2008 335i Coupe

    Need Your Opinions on this Injector Diagnosis

    Wondering if another set of eyes can confirm my next logical step here in diagnosing an issue.

    2008 335i Coupe.

    Car could barely idle. Got it to dealership and they diagnose bad injector #4. Tell me to swap all injectors and it's going to be $6700 plus tax. I laugh, say no thanks, buy one index-12 injector from them and bring it home.

    I've put the brand new injector in #4. Coded it in using INPA. All other injectors are index-9.
    I've replaced all 6 spark plugs. Coils are the same, however.
    Cleared codes.

    I'm still getting rough idle and codes for injector #4. 29D0 and 2E33
    Since sparks are new, I swapped coils #1 and #4 just to eliminate the coil as a problem. No new codes, still getting same codes for Injector #4.

    I finally unplug and plug back in (while car is running) each spark coil wiring harness one at a time. They all make a difference to the sound of the engine (gets worse) when unplugged, except for #4. When I unplug #4 nothing changes, it runs the same. This makes me think that #4 isn't getting power to begin with?? The wiring all looks fine, nothing obvious.



    Questions:
    The final confirmation might be to swap injector #3 and #4 and confirm that #4 still throws the code. Would that confirm to you that it's a wiring/power problem?
    Could it be something catastrophic like a piston seized or something crazy?
    I have read posts about a problem with MSD80 DME's blowing MOSFETS and triggering injector codes - but it seemed like most people report having multiple injectors throw codes when that was the problem, whereas this is only one.


    Thank you all for your help and advice in advance!
    Last edited by njk82; 01-11-2023 at 09:32 PM.

  2. #2
    Join Date
    Jan 2023
    Location
    Niagara, Ontario, Canada
    Posts
    4
    My Cars
    2008 335i Coupe
    *Update*

    I swapped injectors 3 & 4 today. Cleared codes and started it back up.

    It is still throwing the 2E33 code - "Injection valve cylinder 4, input signal"

    When I unplug the 4th cylinder while running, it doesn't make a difference at all - all others bring the engine rpm's down significantly when unplugged temporarily.

    I'm already out of my league here but I can't afford the dealership repair bill so any advice or help would be really appreciated here guys. Thanks so much.

  3. #3
    Join Date
    Jan 2023
    Location
    Niagara, Ontario, Canada
    Posts
    4
    My Cars
    2008 335i Coupe
    Would really appreciate ANY insight here. I've been down for almost 2 weeks trying to figure this out.
    I swapped coils and injectors #3 and #4. Re-coded and still getting same code on Injector #4 - so the problem did not follow the swap.

    This led me to believe it could be a power issue. So using a test light I checked #3 & #4 (shared ground) injector power and coil power. Results:

    #4 Injector Power
    White wire: pulse light
    Orange wire: pulse light

    #4 Coil Power
    White wire: NO PULSE **
    Orange wire: pulse light

    #3 Injector Power
    White wire: pulse light
    Brown wire: NO PULSE ** (no codes show for #3)

    #3 Coil Power
    White wire: pulse light
    Orange wire: pulse light


    I believe the white wire on the coil is the power cable (if someone could confirm?)
    BUT... when I plug a noid light in with the engine running on the same #4 coil, I can see the pulse. Which means it's receiving power and control, no? So I'm not sure if I just wasn't getting enough contact with my test light on it or if it was so faint I couldn't see it but I definitely tried over and over again to see a pulse on the test light when checking it.

    I can go down the line and unplug one coil at a time and the engine idle will drop right down and pop back up again once plugged back in. Nothing changes when I unplug #4. It's definitely not participating in running the engine right now.

    Any insight here? Anything would be super helpful and appreciated!! Not sure what to do next here...

  4. #4
    Join Date
    Mar 2014
    Location
    Rotterdam, NY
    Posts
    1,410
    My Cars
    2011 BMW 328xi Auto
    Have you used a multimeter on injector 4 connector? You might get a light pulse, but are you getting an accurate voltage to the injector. Test all injector connectors to see if voltage is consistent. I think it's 12v to the injector, but don't quote me. Also, check the voltage on the ignition coil injector, just to be safe. Did you check the injector connector contacts for corrosion?

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