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VS V6 Bad miss

Discussion in 'VR - VS Holden Commodore (1993 - 1997)' started by Harvs82, Jul 26, 2017.

  1. Harvs82

    Harvs82 Active Member

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    Over the past couple of years I've replaced the DFI module, and more recently all 3 coil packs with genuine DELPHI units, which worked fine up until last week. Now have have a really bad miss, to the point that the car isn't driveable at all. Replaced all the spark plugs and ignition leads today, and the problem persists. Have tested the resistance on the leads and coil packs, all ok.

    Turned my attention to the fuel injectors, and after disconnecting each one at idle, I found that disconnecting injectors for cylinders 1 and 4 made no difference to the idle. Wiring seems to be ok as we tested with a test lamp, so it looks like the injectors are kaput.

    Where to from here? What do you guys recommend? Engine is mechanically sound apart from the leaking inlet manifold gasket, and has 195,000 original km... as do the injectors.

    Am I up for a small fortune, what do you recommend doing etc...


    Cheers
     
  2. VR38

    VR38 Well-Known Member

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    whilst running, detach one injector plug lead at a time.
    This will perform a balance test.
    If you pull one and the REVS DO NOT CHANGE then that cylinder is at fault.
    If you have spark then it will be a dud injector.
    Has happened to me.
     
  3. gtrboyy

    gtrboyy Well-Known Member

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    1 & 4 cylinders have same ignition coil so that sounds like worth another look..hopefully a simple fix.
     
  4. CCCMikey

    CCCMikey Active Member

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    Is there any danger (apart from getting shocked) if you pull plug leads from the coil packs while idling? (ie gas buildup blowing up the cat etc?)
     
  5. VR38

    VR38 Well-Known Member

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    Holden recommends checking spark at the coil pack, I forget the exact procedure but you can see the spark.
    Alternatively, you can earth a good known plug to the engine and run one lead at a time on it.
    If you think you will over fuel the exhaust etc then pull the fuel fuse.
     
  6. Harvs82

    Harvs82 Active Member

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    Yep that's exactly what we did. Injectors 1 and 4 made no difference to the idle, injector 3 caused the engine to stall.

    Coil packs are barely a month old, all tested under 6 kilo ohms resistance on the secondary side, can't test primary as the multimeter probes don't fit.

     
  7. VR38

    VR38 Well-Known Member

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    Extend them with some jumper wire.
    Alternatively, swap coil locations.
    And/or
    Swap injector locations...
     
  8. Harvs82

    Harvs82 Active Member

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    Looking like the DFI module has shat itself... again. Not terribly impressed given it was a genuine replacement from Holdens not more than 18 months ago I reckon. No spark on cylinders 1 and 4. As a final check I'll swap the coils over, but given the secondary resistance on all of them is fine, and they are virtually a month old I'd expect them to be fine!
     
  9. greenacc

    greenacc Searching for the billion

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    :D DFI's are the work of the devil! :mad:
    Aftermarket ones are shyte too. Not sure if the red MSD ones are any better ?
     
  10. Harvs82

    Harvs82 Active Member

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    Ok well today I grabbed another DFI from the wrecker, and installed that, and the bloody problem is still there... it's still missing really badly at idle to the point it now stalls and is difficult to start but coughs into life.

    Put the original DFI back on now and its still the same, plus a loud ticking noise, which isn't mechanical.

    If I take each lead off individually at the coil, it sparks against the coil pack...
     
  11. greenacc

    greenacc Searching for the billion

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    What codes are coming up?
     
  12. VR38

    VR38 Well-Known Member

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    Pop the bonnet at night, in the dark, have a look what the sparks are doing.
     
  13. Harvs82

    Harvs82 Active Member

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    No codes...
     
  14. Harvs82

    Harvs82 Active Member

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    Switched the coils around tonight... still have nothing firing for cylinders 1 and 4... same injectors also not pulsing.

    Does the ECU cut the spark if injectors fail?
     
  15. greenacc

    greenacc Searching for the billion

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    Don't think the ECU would know which injectors were stuffed.
    Are all the terminals clean on the DFI plug?
     
  16. Harvs82

    Harvs82 Active Member

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    Yep everything perfectly clean. The DFI at best is 18 months old. Coils are a month old. Absolutely giving me the shits now.

    Found that the new leads were also arcing against the heat shields too FFS...
     
  17. greenacc

    greenacc Searching for the billion

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    Are they genuine leads? I think they're the best.
     
  18. VR38

    VR38 Well-Known Member

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    Plugs torqued to spec?
     
  19. Harvs82

    Harvs82 Active Member

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    Not genuine leads but brand new anyway. Plugs brand new and torqued correctly. If I take the lead off cylinder 1 and 4 at idle there's no spark. Have swapped the coils around... same deal, all coils are working.
     
  20. VR38

    VR38 Well-Known Member

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    Maybe some faulty wiring somewhere.
     

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