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Thread: Chevy K30 LQ4 swap issues

  1. #1
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    Chevy K30 LQ4 swap issues

    OK guys im new here but this site has been very helpful.

    I have built rockcrawlers, classic trucks and performed TBI swaps in a few of them.

    This is my first LS Swap and im at the tuning phase and it is kicking my butt.

    OK now the details and questions

    Project Details...

    85 Chevy K30
    Engine - 2005 Express Van LQ4 rebuilt all stock except Summit stage 2 truck cam, Pac springs, trunnion upgrade, speed engineering long headers.
    ECM - 2005 Express green/blue connnectors Drive By Cable
    Trans - NV4500 5speed
    Maf -2005 Express DL-6158
    Harness - BP Automotive H304 99-06 DBC Manual Trans
    Tune - Stock 05 Express tune with the typical stuff removed VATS ect (friend has hptuner software)


    Questions and issues

    Got her fired up and idling perfect but throwing O2 codes,
    I bought the correct o2s for the harness AFS138 AcDelco
    Turns out the harness was built for Case grounded o2s (flat four pin) and the van ecm is for Isolated (sq black plug).
    Called harness guys told me to install a Op system from a 5.3l which has programming for CG o2s.
    Does this sound correct? if so what year and where do i find one.
    Do i have any other options?(rewir/splice o2s to correct plug config?)

    I will learn how to post results on the engine as im having other issues with the TPS and surging but i need to figured this out first

    appeciate your time .

  2. #2
    I had the same issue on my lq4 swap, I just rewired the O2 sensors in my harness. lt1swap.com has the wiring diagrams for the O2 sensors. Go to the 99-07 harness info section and scroll down to O2 sensor information link, it should be everything you need.

  3. #3
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    Awsome thank you. so looking at the two diagrams ,
    Its looks like pins D and C will have to be switched to run IG o2 ?

    Just to be clear im going to cut CG o2 off the plug and then cut the plug off the IG o2 , then switch D to C and A/B stays the same?

    CG o2.JPG

    IG o2.JPG

  4. #4
    Yep, I just had to tie the tan wires in the harness of the O2 leads to my ground for engine harness.

  5. #5
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    Ok good to go I spliced O2?s as stated and grounded to tan to harness, cleared all codes and fired her up .. no CEL so I think I?m good,

    Now my next issue. With everything plugged in, I?m having difficulty getting out of idle, I mean when I give any kind of throttle I get an engine surge no matter what.

    But when I disconnect the TPS the engine revs up perfect . I kept everything or ordered for the 05 express I don?t know what it could be.

    What would be my next step??

  6. #6
    Sounds like abuse mode might be kicking in. Probably need to check that and maybe disable torque managment. Here's a link for how to do it and some other helpful tuning steps/ideas.
    https://forum.hptuners.com/showthrea...ng-Step-inside

  7. #7
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    Quote Originally Posted by 85K5Jake View Post
    Sounds like abuse mode might be kicking in. Probably need to check that and maybe disable torque managment. Here's a link for how to do it and some other helpful tuning steps/ideas.
    Thanks for helping out man! it was still in abuse mode , now shes running perfect ! Back to the mountains

    learned lots of info for squarebody ls swap if anybodys needs part #s or whatever K30/Lq4/Nv4500/np205

    thanks again
    Attached Images Attached Images

  8. #8
    No problem. Glad I could help you out.