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Thread: OBD1 conversion with a LT4 engine

  1. #1
    Carb and Points!
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    Apr 2019
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    OBD1 conversion with a LT4 engine

    Hello. Recently I put a 1996 Corvette LT4 engine into my 1996 Camaro SS. Both 6 speed cars. Car will start and run with the OBD2 computer from my Camaro. But I found a converted LT4 .bin for a OBD1 computer. I did just some small editing, nothing with the tables. And I put the tune on a 1995 Z28 A4 computer I had. Took the tune just fine. She starts right up. But will die after 2 or 3 seconds. Doesn't run bad. Not sure what I need to fix for it to keep running with the OBD1 ecm.

    Any pointers?

  2. #2
    Fuel Injected! sturgillbd's Avatar
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    Jun 2012
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    Has VATS been disabled in the OBD1 PCM?

  3. #3
    Carb and Points!
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    Apr 2019
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    I had checked the vats delete off the tune. But if vats was the issue, wouldn't it just crank and not start? She starts right up. But then dies.

    I went ahead and grabbed another base LT1 T56 tune that best matched my stock LT1 tune but in OBD1 format. And made some changes to the tables by copying some of the LT4 data. And I found some of the LT4 data either missing or way out of line conpaired to the LT1 file. So I went with the LT1 data in those items.

    Have the tune saved and ready to upload tomorrow. Also, I havent switched over my knock sensor to the OBD1 sensor, I thought I could adjust it in the tune, but I'll go ahead and just swap it out. And put my LT4 KM in the 95 ecm case.

    Hopefully that will get me to where I'm looking to be. I'll report back with my results. I'm just trying to see if I can save a couple hundred bucks by doing this myself.

  4. #4
    Fuel Injected!
    Join Date
    Mar 2013
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    562
    It does looks like vats problem. Vette bins have some extra vats protection related to the bcm, that needs to be turned off.
    Strat with good f-body bin and copy all the tables that are lt-4 specific. Spark Advance and VE are one of them and maybe the injectors data.

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