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Thread: Idles very low at startup in park/neutral

  1. #1
    Potential Tuner
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    Mar 2014
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    Idles very low at startup in park/neutral

    Hello,

    I just got done swapping a completely stock 2000 ls1 and a4 into an older Jaguar. Just the standard stuff removed like most swaps (no egr, no air, rear o2 removed, etc). The problem I'm having is I cant get it to idle when you start it in park. It doesn't high idle at all really. It will try to idle at about 380-400 rpm in park with a Desired Idle rpm of 0. If you shift it into drive it will bump up the idle to what you would expect it to be and desired idle bumps too. You can then shift it back into park and it will keep the desired idle rpm that was set when it was shifted into drive.

    I'm a bit stumped why it wont command the correct idle when you start it in park. It runs ok outside of the idle issue. Any ideas what it might be? I've attached my tune and a short log file from a slightly warmed up startup->idle->shift into gear->shift back into park.

    Any help would be greatly appreciated. Thanks.

    ls1SwapMay_01.hpljagls1May_01_.hpt

  2. #2
    Advanced Tuner
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    Jun 2007
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    Finland, Europe
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    It's not your tune, since this is a stock engine.

    Now, at Park and when you start the engine, Idle Desired RPM is 0. And the PCM tries everything to reach that. Ignition advance goes very low. Not good.

    As soon as you shift to gear, Idle Desired RPM goes to 650. Which is good. Engine runs as supposed.

    So there's some, perhaps electrical reason, why Idle Desired RPM is 0 at park.
    Last edited by Pekka_Perkeles; 05-02-2014 at 08:35 AM.

  3. #3
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    Mar 2014
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    Thanks for your input Pekka. Unfortunately, I think you're right about it being an electrical issue and not a tune issue.

    I took the ecu out of the jaguar and put it into my bone stock ls1 2000 Camaro and it fired up and ran as one would expect. So, its definitely something in the harness, sensors or some other electrical component. This isn't my first time doing a swap by any means. Ive done a 5.3 and a 6.0 into and I did the entire harness from scratch on the 5.3 and modified a stock harness on the 6.0. Both went flawlessly and are daily driven.

    I know this is a site for tuning the ecu, but if anyone has any ideas on how to diagnose and narrow down my problem I'm all ears. I've swapped out the maf and the throttle body from my 2000 camaro and it had no affect. So i'm pretty confident its not the iac, tps or maf. What would cause it to command 0 rpm idle? What part of the tune controls the command idle rpm? Other then the p/n status and ect? Maybe if I know what controls the Idle Desired RPM I can narrow down my electrical issue.

    Thanks

  4. #4
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    Join Date
    Jul 2008
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    Hi!

    Did you figure this one out?

    Customer brought a Stepside w LS1 conversion to my shop today since there was no idle.

    Desired ilde is 0rpm.

    Regards Marco
    Last edited by Marco Garver; 07-08-2014 at 10:14 AM.

  5. #5
    Tuner
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    May 2008
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    Did you solve this issue? My also sometimes show desired idle RPM at 0 or 63 or 138rpm
    LS1 383ci 98' FBody, turboed, 00' PCM, 4L80E, 90# FIC injectors
    110ci Nissan 200SX, 25psi, 370whp