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Vt 3.8 missfire

Discussion in 'VT - VX Holden Commodore (1997 - 2002)' started by Jack pollock, Feb 10, 2019.

  1. Jack pollock

    Jack pollock New Member

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    So I have just finished a motor swap put everything back together starts and idles fine. So I took it for a drive and it backfires out of the exhaust and shudders and struggles when giving it gas then when you stop it dies any ideas??
     
  2. Brysha89

    Brysha89 Member

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    Check all Vacc hoses at the back of the engine are connected if so then the flywheel is miss aligned were the engine connects to the torque converter and gearbox did a engine change last year in a old VX i had i had the same problem after install but mine was a vacc hose and it will need a tune as your ecu is tuned to the old engine.
     
  3. Jack pollock

    Jack pollock New Member

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    The motor and gbox were complete never been separated and I have checked all the vac lines they are all in the right place
     
  4. Brysha89

    Brysha89 Member

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    well if all vacc hoses at the back of the engine are on, i don't need to ask about the front, it would definitely need a ECU tune as when i installed my ecotec to the VX i had shuddering too i thought it would be ether a engine or gearbox mount took it to my mechanic he said it needs to be tuned to the engine thats what is causing Struggling, back fire and shuddering after a certain speed.
     
  5. Brysha89

    Brysha89 Member

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    Unless there is more sinister noises from the engine besides the shuddering that will set you back an hours work at a mechanics and cost me 150 for the tune so dont pay more than $300 for a mechanic to get it right .
     
  6. _R_J_K_

    _R_J_K_ Well-Known Member

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    No it won't, in terms of engine management all Ecotecs are effectively the same. Would really love to know what 'tuning' this mechanic did for $150.

    OP, I'd do basic service stuff first if you haven't already and don't have a history on the engine. Plugs, leads, the obvious stuff.
     
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  7. Brysha89

    Brysha89 Member

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    I'm No Mechanic i was told that by my last mechanic as i did an ecotec engine swap and had exact same problem as the first post by jack pollock, when i changed the engine plugs and leads were new when i installed it had the shuddering, lack of power at certain speeds and my last mechanic told me just needed to be tuned . Now i dont go to any mechanics now i can self diagnose with my scan tool but that was what i was told the last time i did and ecotec engine last year, i now own a super 6 vt and LS1 Statesman.
     
  8. _R_J_K_

    _R_J_K_ Well-Known Member

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    Well whatever he did, it wasn't a tune, not for $150. It's not something you can just go down to the local for, and it costs a lot more from reputable shops.

    Shoulda asked him for a dynograph.
     
    Last edited: Feb 13, 2019 at 10:37 PM
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  9. VT2Commie

    VT2Commie Active Member

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    Something was damaged in the engine swap for sure. Knocked and cracked something. Stretched or pulled something. Broken cracked sparkplug, coilpack, etc. stretched/pulled spark plug lead/s, electrical harness. I could keep going but you get the drift. Check everything again and then physically check it again. Did I say check everything again? Yeah I did, check everything again.
     
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