stumped after engine swap ~ 5.3 to 4.8 in 2006 Z71

Discussion in 'GM Powertrain' started by sheldon70, Sep 18, 2013.

  1. sheldon70

    sheldon70 New Member

    I changed out my 5.3 to a 4.8 in my 2006 z71 it will turn over but will not fire have already changed out coil packs any suggestions would be appreciated
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    We might need more info on this one. Did you change the ecm? did you have it reprogrammed? How is the fuel pressure?
  3. sheldon70

    sheldon70 New Member

    Has got good fuel pressure. No didn't know I had to change the ecm also think security system may have faulted out because when I turned the key over lights went to flashing and horn honking
  4. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    Hopefully someone else can help here. I am pretty sure that the ECM control timing, fuel delivery, and a bunch of other things. I am going to move this thread into the power train sub forum to get you better results
  5. sheldon70

    sheldon70 New Member

    Thank you for your help
  6. GM Customer Service

    GM Customer Service Epic Member 5+ Years 500 Posts

    I understand that you are looking for assistance in resolving your vehicle issue yourself and I might not be able to give you any technical advice. If you find that you cannot resolve this vehicle concern yourself, I am happy to assist with any general questions or concerns you may have.


    Jennifer T.
    GM Customer Care
  7. j cat

    j cat Epic Member 5+ Years 1000 Posts

    with the security light on the vehicle will not start. now I do not understand why an engine swap would cause the security to be activated.

    since the engine is cranking then I would measure the fuel pressure. engine swaps could mean many things . give details about the replacement engine . what you did to do with this swap ? engine come with manifolds intake exhaust/throttle body/same year or what year ? injectors /coils with engine or swapped stupid stuff like this .....
  8. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    @sheldon70 has the engine ever run in the truck?
  9. darnie1987

    darnie1987 Rockstar 100 Posts

    make sure your getting spark and fuel first off. and id look intom a pcm or a tune.... also what did u do a 5.3 to a 4.8???

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