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Thread: Intermittent Acceleration Issue - TunerPro file attached

  1. #1
    Carb and Points!
    Join Date
    Jul 2014

    Intermittent Acceleration Issue - TunerPro file attached

    I spent many hours going through threads and reading these boards before I started the TBI swap. It was a 99% success.

    I stepped up and I finished my TBI swap with a 7747 ECU, new fuel tank with in tank pump, 12 PSI all the way through, all new sensors, 4 wire O2, on a 350 in a 79 Blazer. I am running dual exhaust that exits behind the rear tires. I'm running -6an steel braided lines both directions. The lines are a little closer to the driver's side exhaust as it goes into the engine bay than I want, but it is what it is (runs up the frame rail). I am running a TBI adapter plate with a spacer for EGR clearance (positive pressure type) on top of an Edlebrock performer carb style intake. I think it is the 3701.

    The thing passed emissions on visual and numbers last week. I am getting a flat to no acceleration at intermittent times. It starts great, idles great, runs perfect and then out of the blue, sags and goes flat. It feels like vapor lock. I will be driving down the road, and then lose all power. It will barely maintain speed with no chance of accelerating. I put it into neutral, revved the engine and under no load, revs up. Put it back in gear, flat, hesitates and then powers back up. No codes being thrown until last night. I got these codes last night - first time - 32, 42, 43 and 44. I did replace the junkyard ESC with a new one I had purchased for the swap. Drove today - no codes.

    I thought the sagging and flat running was related to the EGR so I removed the EGR (used a block off plate) and no change. Still had sagging a couple of times today. The passenger side injector is not spraying as strong or in the same nice pattern as the driver's side. I switched wire plugs (swapped sides) - no change. Swapped injectors and the problem stayed on the passenger side. The O2 is on that exhaust side.

    I attached two TunerPro RT files to the post. One was grabbed after I stopped, filled the tank and had no acceleration driving through the parking lot. The other occurred after the first. The thing was running again, then ran flat for a few seconds and then powered back up to pre - event levels.

    I'm stumped. I've gone through the wiring and I cannot find anything obvious. Any ideas or assistance would be greatly appreciated.

  2. #2
    Fuel Injected!
    Join Date
    Sep 2012
    washington indiana
    in tuner pro look at item list then at the top open eeror codes, you have 4 maybe a vaccum leak.

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