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Thread: Cold idle stumble

  1. #1

    Cold idle stumble

    Hey Guys,
    Just wrapping up a tune on a 2014 VF Commodore (E38/L77 engine) and I'm having an issue with the cold startup.
    The engine fires up well but at around the 10 & 25 second mark (as seen in the log attached) the commanded EQ dives and the engine stumbles then recovers.

    Has anyone come across this issue and have a fix?

    Thanks,
    Chris

    23-06-08 08-21-21 cold start.hplcold start.hpt
    Last edited by LightningPerformance; 06-08-2023 at 02:35 AM.

  2. #2
    Tuner
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    Can you post the tune file and provide more details on the car.
    Last edited by JasonHSV; 06-07-2023 at 08:59 PM.

  3. #3
    Tuning Addict blindsquirrel's Avatar
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    There are two .hpl log files posted, no tune file to look at to see what settings produced those logs.

  4. #4
    Quote Originally Posted by blindsquirrel View Post
    There are two .hpl log files posted, no tune file to look at to see what settings produced those logs.
    Crap sorry didn't even pick up on that! try this one

    cold start.hpt23-06-08 08-21-21 cold start.hplcold start.hpt23-06-08 08-21-21 cold start.hpl

  5. #5
    Quote Originally Posted by JasonHSV View Post
    Can you post the tune file and provide more details on the car.

    Sorry Jason, just been brought to my attention I posted 2 logs I have updated the original post thanks.

    2014 VF SSV ute. Small cam. auto. std converter. Vehicle was previously blown but is now N/A.

    I have dynoed the vehicle, everything is mint. Just this cold start issue. The issue is not present during hot starts.

  6. #6
    Tuner
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    So you're using a 2 BAR SD patch OS but running it in MAF only. I'd personally turn the maf off and tune the SD table.

    The SD table looks off and might be causing something wonky to go on in the background even though its in maf only.

    Looking at your coolant temp and intake air temp (would have been good for you to log intake valve temp) the issue would probably be in the open loop tables. To confirm that's it, you might like to try setting all the tables in Fuel - Open Loop / Base - Open Loop & Open Loop Gains to a value of 1 across the board and see what your commanded EQ is then.

    Cheers,

    Jason
    Last edited by JasonHSV; 06-08-2023 at 07:06 AM.

  7. #7
    Quote Originally Posted by JasonHSV View Post
    So you're using a 2 BAR SD patch OS but running it in MAF only. I'd personally turn the maf off and tune the SD table.

    The SD table looks off and might be causing something wonky to go on in the background even though its in maf only.

    Looking at your coolant temp and intake air temp (would have been good for you to log intake valve temp) the issue would probably be in the open loop tables. To confirm that's it, you might like to try setting all the tables in Fuel - Open Loop / Base - Open Loop & Open Loop Gains to a value of 1 across the board and see what your commanded EQ is then.

    Cheers,

    Jason
    Jason,
    I tried what you suggested this morning, EQ ratio stayed consistent, however the issue still remains. Massive injector pulse then it goes away. Has got me stumped!

    Thanks.
    Attached Files Attached Files

  8. #8
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    You missed a group of tables (see attached), set these to 1 across the board and retest. I'm sure that's your problem.
    Attached Images Attached Images