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Thread: Critique my tune - cold idle rough, feel like I might be leaving power on the table

  1. #1
    Tuner in Training 98Birdman's Avatar
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    Critique my tune - cold idle rough, feel like I might be leaving power on the table

    First of all, I am new to tuning. I studied and read up and have a basic knowledge and I feel like I got the car to a good point but I know it needs more tweaks. When you experienced guys look at the log and tune you'll probably see all kinds of shit, but the car runs pretty good right now but I know I have a lot that can be done. Cold the car is a pain in the ass. Once it warms up it is great.

    I was having MAF issues so the tune may have spots that need changed because I tweaked it a bit before I realized that the old descreened MAF was dying and causing issues. I replaced it with a new screened MAF and it is a lot better but I know the tune needs work. It is a long log file, I logged my whole drive in to work today. It is a lot of cruising with a few easy starts and a couple blasts. At the end of the log there is a WOT hit from 20ish up to about 70.

    Let me know what you guys think.
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  2. #2
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    It's pretty rich at WOT, and has too much timing. It would be a lot happier around 12.5:1 AF ratio, instead of 11.5:1.

    I pulled several degrees of timing out, both at idle and WOT.

    It was too lean at idle. That's causing you some cold start issues.

    Try the attached tune and see how it performs.

    tatune 4-22modified.hpt

  3. #3
    Tuner in Training 98Birdman's Avatar
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    Thanks! Won't let me open it though, says newer or unsupported version. I am on MPVI if that makes a difference.

  4. #4
    Tuner in Training 98Birdman's Avatar
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    nevermind, got it. Had to upgrade to the beta

  5. #5
    Tuner in Training 98Birdman's Avatar
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    Quote Originally Posted by kevin87turbot View Post
    It's pretty rich at WOT, and has too much timing. It would be a lot happier around 12.5:1 AF ratio, instead of 11.5:1.

    I pulled several degrees of timing out, both at idle and WOT.

    It was too lean at idle. That's causing you some cold start issues.

    Try the attached tune and see how it performs.

    tatune 4-22modified.hpt
    Seems to be pretty strong. On initial start it seemed to be pretty lean, idle kind of hunts a bit but about what it was before.

    I guess maybe engine specs might help? LQ9 6.0L .02 over with flat tops, stock heads mild porting and bigger valves. FAST 92mm intake and NW throttle body. Futral F13 112cl cam. 230/232 591/585 112cl. Longtubes, 6-spd, Moser 9" with 4.11 gears.

  6. #6
    Tuner in Training 98Birdman's Avatar
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    log file
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  7. #7
    Tuning Addict 5FDP's Avatar
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    Are you positive you have zero intake leaks and exhaust leak pre o2 sensor?

    Those trims at times will go off the charts lean. Always heard those fast intake had leaking problems and where not worth the money to upgrade.

    I also don't think setting the idle timing to 32 degrees is a good idea. Try to aim for low 20's.
    Last edited by 5FDP; 04-22-2019 at 02:10 PM.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  8. #8
    Tuner in Training 98Birdman's Avatar
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    yeah, I tested the intake with carb cleaner and it doesn't seem like it is leaking at all. No exhaust leaks either, I just put it all on and checked that there were no leaks.

  9. #9
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    There's definitely something going on with those fuel trims...primarily at idle. It's hard to say what it is though. I wonder if there's something going on with the MAF sensor? Try disconnecting it and see if the cold start and idle is better.

  10. #10
    Tuner in Training 98Birdman's Avatar
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    Found some new tables specific to my SVO red tops so entered that info in there and played with a few things. I feel like I picked up power and my idle is a little better. I think I put way too much timing advance in it though.
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  11. #11
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    On that OS, you need to tune the secondary VE table, apply to the primary and smooth it. And like 5F said, idle timing low 20's. Base, friction and start up air flows need looked at too, that will help with cold start issues.