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Thread: No power after swap! Horsepower that is.

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  1. #1
    Join Date
    Jan 2007
    Location
    Lewisville,TX
    Posts
    94

    No power after swap! Horsepower that is.

    Guys I'm so frustrated with how this whole swap has gone, I literally hate this truck! Here's the details tell me what you think. Ideas on what to do. Thx
    4.8l with ls1 intake, 212/218 cam, long tubes, no cats 2.5 pipes to magnaflow mufflers, one of which I had on before the swap. Stock trans and converter with 90k and worked just fine before. Lots for ppl use this cam with stock converter and videos prove it sounds good, the lope i mean. Mine does not! It starts, runs/idles very good. Just doesn't sound like it has a cam??
    The PCM has been basically mail order tuned, vats off and given specs of my cam. At LG Motorsports, a local corvette tuning place. Will no dyno tune cause no power? I mean this truck will barely go up my driveway. I plan on taking it back to them but I have to drive it there and I'm scared. Lol.
    95 Chevy, bagged and bodied, LSx swap/detail in progress

  2. #2
    It should be a fairly stout setup, do you have any way to scan or datalog? Do the harness, pcm, and operating system match? Ive read where others ran into issues mixing car/truck parts.

  3. #3
    Join Date
    Jan 2007
    Location
    Lewisville,TX
    Posts
    94
    My Mcheck engine light is off and on. I used a code reader and only got code for gas tank something cuz of my fuel cell. Never did that before swap. Engine and PCM from same truck, PSI standalone harness.
    95 Chevy, bagged and bodied, LSx swap/detail in progress

  4. #4
    Have you pulled and read the plugs? Or can you tell if its dumping raw fuel out the pipes? Or maybe misfiring? I did a 5.3 swap a few years ago and that engine had been sitting long enough for the injectors to stick, it sputtered, popped, and fouled plugs, stuck a set of pullout injectors in and its smooth as glass.

    Just for reference, it was a 94 short bed, stock lm7 with tsp224r, stock 4l80e, stock converter, 3.42 gears and tune. No track times, but the one time I raced a buddies 2002 short bed 5.3l, tune, 4.10s, etc, it was a bloodbath, probably put 7-8 car lengths on him and we were spinning on the launch and had to let off.

  5. #5
    Join Date
    Jan 2007
    Location
    Lewisville,TX
    Posts
    94
    Yes I noticed some dark oily/fuel from the left header. Just pulled plugs and they don't look new, which they are. Left side looks worse than right too. I not a mechanic, but a good parts replacer. Injectors are used camaro stocks. Smells like raw fuel when running. Maybe they cranked the pressure up? If that's possible.
    95 Chevy, bagged and bodied, LSx swap/detail in progress

  6. #6
    Join Date
    Jan 2012
    Location
    warwick ny
    Posts
    247
    Make sure you have spark on each cylinder.

  7. #7
    Join Date
    Jan 2012
    Location
    DFW, TEXAS
    Posts
    594
    Quote Originally Posted by dimebagged View Post
    Guys I'm so frustrated with how this whole swap has gone, I literally hate this truck! Here's the details tell me what you think. Ideas on what to do. Thx
    4.8l with ls1 intake, 212/218 cam, long tubes, no cats 2.5 pipes to magnaflow mufflers, one of which I had on before the swap. Stock trans and converter with 90k and worked just fine before. Lots for ppl use this cam with stock converter and videos prove it sounds good, the lope i mean. Mine does not! It starts, runs/idles very good. Just doesn't sound like it has a cam??
    The PCM has been basically mail order tuned, vats off and given specs of my cam. At LG Motorsports, a local corvette tuning place. Will no dyno tune cause no power? I mean this truck will barely go up my driveway. I plan on taking it back to them but I have to drive it there and I'm scared. Lol.
    I bet that was pricey. was it a new cam? which springs and pushrods? Nelson performance is your answer

  8. #8
    Join Date
    Dec 2004
    Location
    San Antonio, TX Area
    Posts
    1,741
    Does the throttle body butterfly open up all the way? DBC or DBW?
    "ALisSa1 Silverado"
    1990 Chevrolet RCSB 2002 Chevrolet Camaro LS1/4L60E
    Scrimpin Ain't Easy
    ( . Y . )


  9. #9
    Join Date
    Sep 2008
    Location
    Arizona/Utah
    Posts
    3,939
    Any exhaust leaks?
    ECSB 2kSierra 2wd 4.8L-K&N-HPtuners-Calspeed LT's-Magnaflow-Tahoe20's-HankookRH06

    waiting to go in... 3.90s, 214/220cam

  10. #10
    Join Date
    Jan 2007
    Location
    Lewisville,TX
    Posts
    94
    I have a aftermarket external pump going to the corvette filter. Slow94 I think that may be the rich problem.
    Yes at LG it was $375, I could go back for the rest of tune but I don't have a trailor. Nelson was a choice but I went for local. Guy at my work had I send his PCM back 2 times to get the tune right.
    I haven't checked how open the TB is, great idea.

    I have a local tuner coming over next week. We will see what happens then?
    95 Chevy, bagged and bodied, LSx swap/detail in progress

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