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Thread: Truck won't start with cos3. Runs fine with regular file. 12587603/04073003

  1. #1
    Junior Member
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    Default Truck won't start with cos3. Runs fine with regular file. 12587603/04073003

    I'm running a 12587603 OS, the truck cranks, idles and runs great but it is boosted so I did the cos upgrade with 04073003 and followed the instructions exactly and it will not run. The most I get is a brief start then just shuts down like vats would do but it is disabled. Plugs are wet also. Every table is the same including ifr. I'm using this tune because it is dbc, boosted and flex fuel. I'm using the correct van ecm also. Thanks for any help you can give. On a side note I have used cos OS many times before with no trouble.

  2. #2
    Lifetime Member GMPX's Avatar
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    It has been a LONG time since I looked at the LS1 COS's, but from memory people used to get caught out with one of the multipliers set very high by default (depending on what was already in the blank space we used). I know this is covered in the doc, but maybe just check them, it might not have been something you have had to do in the past.
    I no longer monitor the forum, please either post your question or create a support ticket.

  3. #3
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    The only thing I think I may not have done is set the oor values lower, save, close tune file, then change back and save. Would that be causing this problem?

  4. #4
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    I just changed them, or left them if they were at the value that the tutorial said to set them at.

  5. #5
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    Ok, I found the problem. Or think I did. I had the map scaling slightly off and it was in boost ve table at idle. Now that i have it on the main ve it seems that the commanded fuel vs rpm vs map tables are defining the fuel. I know these tables are optional so I would like to disable them. How do I do that?

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