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Thread: Ls1 idle issue

  1. #1
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    Ls1 idle issue

    So Ive looked all through here and not seeing exactly the issue I have going on with my idle.
    Car is a 04 GTO
    Ls1 stock bottom end., tick stage 2 cam, lsxr 102 intake, nw 103 throttle body, ported 799 heads, milled . 012, .040 cosmetic head gaskets, fic 42# injectors
    This issue started when I installed the intake and has persisted even through a Dyno tuning, I've contacted the tuner and he says well it was fine when we street tested it . Which I'm calling bullshit on. They say well we can put it back on the Dyno for 1/2 price and have a look at it..
    Any way.. what it does is as I come into a stop push the clutch in it'll drop to about 400 rpm and bounce to 12 to 1500 rpm and continue to do this bounce for about a minute before settling into the 950 idle
    I've tried adding butterfly opening to set iac to 20, tried 40 , 60 and even 80 to 100 steps . Even drilled a 1/8th hole in the plate like factory tb.replaced tps twice, replaced iac twice, smoke tested twice, checked all the wiring, tried with pcv hooked up oem and with it plugged. so at this point im thinking it has to be a tune thing. I really haven't touched the tune because as far as idling stuff in hp I'm lost.. I'm a carb and distributor vacuum timing light guy .. so I'm here to ask for help on where to go in the tune to fix this..
    Not sure where to attach the log and tune file here.. uhf
    04 gto is the tune they gave me on the usb
    the csp evap disabled is the tune i pulled from the ecu.
    Attached Files Attached Files
    Last edited by Crimedog; 17 Hours Ago at 06:02 PM.

  2. #2
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    That looks like a canned "tune" was put in, then possibly they ran it on the dyno to get a MAF curve, but that is doubtful. The only VE tuning that has been done looks like a failed attempt to get the idle correct, then some auto-smoothing to make the graph look pretty. Your fuel trims are terrible, even though it is MAF only above 1400 rpm, which should have been easy to tune. I question the reasoning behind some of the PE changes, and the spark table changes seem a bit like lazy work. On the bright side, it looks like the fuel injector data was changed in the correct tables, lol.

  3. #3
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    well that would explain some things
    like why it dyno'd @368whp, and idle issues,, also upsets me a bit they had my car a weak and charged me 1600 for the tune only..
    makes me wonder if uploaded wrong tune. ill upload the tune i pulled from the ecu.
    but thank you

  4. #4
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    Here is a stock file from the repository you can use to compare the changes made to your tune.
    Attached Files Attached Files

  5. #5
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    ok ,
    thank you will do

  6. #6
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    Thats really sad to see.
    And yea look at your fuel trims with idle is struggling.

    Its going to need to be cleaned up some.
    Unfortunately its going to be time to learn how to fix it yourself or hire it out.

  7. #7
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    yea thats what im trying to do, figure this out myself.
    im trying to find comparisons tp what i know,
    im old school engine builder ecu stuff is pretty new to me,
    my tuning skill set is a box of jets and power valves, a progressive timing light and a vacuum gauge, box of springs and shims and weights for the distributor lol.

  8. #8
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    I'm really kicking myself in the ass now because i didn't go with a carb swap route like i originally intended,
    but live and learn right,

  9. #9
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    Some basic comparisons (very oversimplified and basic) are as follows. The VE table and the MAF are both capable of doing what your jets do. The VE represents how much airflow the engine ingests. The MAF directly measures airflow. They both have to be programmed (because GM blends the info from both) in order to know how much fuel to inject. The PE enrichment table does what your power valve would do by richening the mixture under load. Your vacuum is measured by the MAP sensor, which reads in absolute units starting at 0 as a perfect vacuum and going up from there to atmospheric pressure, instead of starting at atmospheric and going in minus numbers like a vacuum gauge. Your spark control is far more capable than what you can do with a distributor, as you can program spark tables (and multiple modifier tables) to make your spark almost anything at any exact rpm and cylinder fill, instead of dealing with a vacuum pot and centrifugal weights. Almost forgot, there are transient fueling tables that are sort of like squirters, but far more precise, and you usually don't have to mess with those if you use a stock intake manifold. All the info is available on the forum, but it is a lot to take in at first.

  10. #10
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    thank you,, this is more helpful than you know .
    thank you

  11. #11
    Advanced Tuner abc's Avatar
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    idle issue.png

    I assume this is the point you disengage the clutch? Timing is pulled way down in an attempt to get the idle to come down or DFCO, then a bunch of fuel is added in attempt to satisfy the NBO2's, probably not gonna work like that.

    Show this log to the tuner, if he still wants to charge you to fix it, I would let him know your gonna tell everybody what kind of work you received for 1600 bucks. Better yet, learn how to fix it yourself and tell him to clean up his act.

  12. #12
    Tuning Addict edcmat-l1's Avatar
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    Quote Originally Posted by Crimedog View Post
    They say well we can put it back on the Dyno for 1/2 price and have a look at it..
    Why would they need to put it on a dyno for a return to idle problem? Go by and have them go for a ride with you.

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  13. #13
    Tuning Addict edcmat-l1's Avatar
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    Quote Originally Posted by Crimedog View Post
    well that would explain some things
    like why it dyno'd @368whp, and idle issues,, also upsets me a bit they had my car a weak and charged me 1600 for the tune only..
    makes me wonder if uploaded wrong tune. ill upload the tune i pulled from the ecu.
    but thank you
    Holy shit I need to raise my prices!!

    Tune is not very good.

    You're not logging all the pids you need for idle tuning.
    Last edited by edcmat-l1; 5 Hours Ago at 06:23 AM.

    EFI specialist
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  14. #14
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    yea im working on it ,
    the putting tables to what i know that game tech gave me helped me alot
    i have contacted him and i was told he had 0 issues when he road tested.

  15. #15
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    Quote Originally Posted by Crimedog View Post
    So Ive looked all through here and not seeing exactly the issue I have going on with my idle.
    Car is a 04 GTO
    Ls1 stock bottom end., tick stage 2 cam, lsxr 102 intake, nw 103 throttle body, ported 799 heads, milled . 012, .040 cosmetic head gaskets, fic 42# injectors
    This issue started when I installed the intake and has persisted even through a Dyno tuning, I've contacted the tuner and he says well it was fine when we street tested it . Which I'm calling bullshit on. They say well we can put it back on the Dyno for 1/2 price and have a look at it..
    Any way.. what it does is as I come into a stop push the clutch in it'll drop to about 400 rpm and bounce to 12 to 1500 rpm and continue to do this bounce for about a minute before settling into the 950 idle
    I've tried adding butterfly opening to set iac to 20, tried 40 , 60 and even 80 to 100 steps . Even drilled a 1/8th hole in the plate like factory tb.replaced tps twice, replaced iac twice, smoke tested twice, checked all the wiring, tried with pcv hooked up oem and with it plugged. so at this point im thinking it has to be a tune thing. I really haven't touched the tune because as far as idling stuff in hp I'm lost.. I'm a carb and distributor vacuum timing light guy .. so I'm here to ask for help on where to go in the tune to fix this..
    Not sure where to attach the log and tune file here.. uhf
    04 gto is the tune they gave me on the usb
    the csp evap disabled is the tune i pulled from the ecu.
    Lot of shops will get a dyno and a HPTuners cable and all of a sudden feel qualified to tune everything in the supported vehicle list.

    In the short log you posted, the fuel trims are pretty far off. Most idle issues are actually over fueling issues. Too much fuel will cause the engine to surge, stall, choke out, etc.

    One you get the fueling correct we need to see a log with IAC counts, LTIT and STIT. That will tell us if your IAC is in range to save the idle and if the base idle running airflow tables are correct.
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