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Thread: Idle AFR and Start Up Fast102/102tb

  1. #1

    Idle AFR and Start Up Fast102/102tb

    Hello everyone,

    I am a new to tuning so if I say something incorrect or something that doesn't make sense let me know. Don't bash me for it.

    My car is a 2006 gto 6speed. Intake, ls3 Maf, Fast 102/102tb, headers and exhaust (stock cam and valvetrain). Car was tuned by Jeremy Formato of FastProms.
    WOT the car is perfectly fine with a proper 12.9:1 afr and no KR* detected on the scanner. Makes great power on the dynojet 412/410 so no complaints there. I have an LC2 wideband hooked up to the car so I can see what's going on with the fueling all the time.

    I am a little bit worried about the AFR particularly at start-up(cold) and light cruising. Sometimes at start up the car starts a little rough with some sporadic timing changes/flux (for lack of a better term) and goes away as it warms up. AFR on a cold start is around 14 and when warmed up the wideband will oscillate between 14.9-16 when warm at idle. Cruising around town the car is at 15-16 AFR. To me this feels as if my commanded AFR is 15 even though the VCM editor indicates that the values are set to 1/stoich. Is there a sticky thread that pertains to this? I have already read through the GEN4 tuning stickies and in the past have honed my fuel trims down more or less so I am not completely in the dark about how to go about it but the car just feels weird too me. Jeremy assures me that he honed the fuel trims down but I just don't buy it, when I first attempted to tune this set up I did a much better job at honing down the fuel trims than he according to my wideband and scanner. I will post Datalogs asap

    Thanks

  2. #2
    Senior Tuner SultanHassanMasTuning's Avatar
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    post tune, maybe there is changes to the stoich and open loop tables which is a state of how the car will react before completely warming up
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  3. #3
    Quote Originally Posted by SultanHassanMasTuning View Post
    post tune, maybe there is changes to the stoich and open loop tables which is a state of how the car will react before completely warming up
    cold start scan wierd timing.hpl

    here is a scan of this mornings cold start, today it started up perfectly fine. my wideband indicates a lean condition while the HPTuners scanner shows rich. Obviously I can rule out the Lean issue to having to reset my wideband. but the problem that remains is my spark advance. it is quite sporadic and it gets low enough to cause the rough idle that im feeling

  4. #4
    Advanced Tuner
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    There is just too little evidence to really pinpoint the issue.

    Post your tune and perhaps some additional logs as well.

    Remember that your car MAY have a simple mechanical issue, such as leaky exhaust near wideband, which has nothing to do with a tune as such.

    Furthermore, I'm not saying your car HAS a mechanical issue. But without a tune and logs, it's difficult to say.

  5. #5
    I will post my tune asap. Thank you for bringing up a good point. Up until very recently i had some low operating voltage issues. Some extra wiring and grounds fixed it. i have had Jeremy check for intake manifold leaks; everything was fine in that department. I do have a minor exhaust leak, on the connection pipes from my headers to my xpipe but its so miniscule that it can only be detected with a stethoscope. I do get an occasional metallic rattle and a tick on cold starts but even with a stethoscope i cant pinpoint where its coming from if its in the engine so i can only assume that its a rattling bolt or washer somewhere in the engine bay.

    My axles are going bad and have developed extra drivetrain slack, i believe that maybe this may interfere with a TPS Tip In while driving( i read this somewhere a while back and cant recall exactly how it went so if it sounds rediculous or makes no sense please disregard ).

  6. #6
    Potential Tuner
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    any update on this issue? experiencing the same and also had the same person tune mine

  7. #7
    Yes, commanded open and closed loop slightly richer (EQ RATIO 1.00, RICHENED TO 1.02-1.03), your gonna have sit there and furiously tune your STFTs, then clean up whatever is left over by tuning your LTFTs on a loaded dyno or open road.

    P.S. check your idle airflow table, if unsure start from the stock table download a stock tune, copy and paste, test it.
    Then add 10 percent across the board. If the car has trouble returning to a steady commanded idle rpm after bliping The throttle reduce a percent and repeat and test till satisfied with the results... Good luck

  8. #8
    Advanced Tuner
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    I recently installed a fast lsxrt102. And I was getting a lot of start up flare, and even during cruise it seemed to rev when the converter unlocked.

    I had to drastically decreased my startup airflow, my minimum airflow , and my startup flare spark.

    And I spent a lot of timing adjusting the VE with my stft .
    Also Ignore the wideband for the light throttle tuning i had best luck using the wideband just for WOT.