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Thread: Only 5psi bad misfire

  1. #1
    Potential Tuner
    Join Date
    Dec 2017
    Posts
    8

    Cool Only 5psi bad misfire

    2008 cobalt ss ldk swap on S256

    The car is missing really bad after about 6psi it falls on its face after a few drives got a random misfire code.

    note* car ran fine for the first 2 days this started happening on the third day (brand new engine/sensors/everything)

    1. tried changing coils & plugs
    2. compression dead even on all cylinders
    3. boost leak tester no leaks at 25psi
    4. gapped spark plugs

    run after exhaust.hplrun home.hpl


    Mods:
    86mm wesico pistons
    K1 rods
    ZZP Turbo Piping
    Bigger fuel pump lobe
    Lt1 fuel pump
    balance shaft delete
    Opels
    S257
    Tr10 intercooler
    38mm wastegate
    Blow off valve
    Full exhaust (catted)
    Upgraded map sensors
    E47
    Stage 3 clutch masters

  2. #2
    Advanced Tuner
    Join Date
    Apr 2011
    Location
    Chicago, IL
    Posts
    763
    1st off your fuel trims are pegged lean at idle so you need to verify that you do not have any vac leaks and fuel pressure is proper and fix the airflow model - ive never used the lt1 fuel pump on a lnf/ldk before so im not sure it will work correctly given im sure the internal attributes are different to a point. Cyl 2 and 4 seem to be the problem childs and you've appeared to of swapped coils and plugs to no success and have good compression - what were your readings?. could possibly be an injector issue. is it a brand new engine or used - same same with the injectors? just a question because sticky valves are known to cause misfires along with shitty fuel - did you recently just fill up? but with your trims being as lean as there are and if everything checks out fine vac leak wise/fuel pressure then you need to work on getting the airflow model tuned better because then it could just be a lean misfire but hopefully it doesn't have anything to do with the fuel pump. add current misfires to you pids and desired fuel pressure
    also what plugs are you running and at what gap?stock coils? tune file would also help
    Last edited by TCSS07; 02-25-2019 at 05:04 PM.

  3. #3
    Potential Tuner
    Join Date
    Dec 2017
    Posts
    8
    brand new LDK block straight out of the machine shop, brand new opels aswell. stock plugs and coils. getting new plugs tomorrow and changing maf out with my old good one. compression is at 150psi in every cyclinder.
    Jordan257-E47-01.hpt

  4. #4
    Potential Tuner
    Join Date
    Dec 2017
    Posts
    8
    turned out it was a mixture of zzp rewire kit/coil pack/bad gas

  5. #5
    Advanced Tuner
    Join Date
    Apr 2011
    Location
    Chicago, IL
    Posts
    763
    good, glad thats handled but if that doesn't fix your trim issue you need to work on tuning the airflow model

  6. #6
    Potential Tuner
    Join Date
    Dec 2017
    Posts
    8
    Yeah I'm getting tuned by Kevin he just sent me a base map then this happened lol