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Thread: Why does this engine want to idle at 1500RPM

  1. #1
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    Question Why does this engine want to idle at 1500RPM

    Stock 6.0 Block
    Brian T Stage 4 Cam With upgraded springs and trunions
    GMPP CNC ported LS3 Heads
    Stock LS3 Intake and Injectors 42lb
    100mm Throttle Body DBC
    Built 4l60e with 3900 Stall converter

    I have updated the Injector Flow Rate, and I have played with all the tables I could think of. ECM was from a 5.3 and I have tried to modify accordingly but for the life of me I can not figure out why the heck this thing wants to ideal at 1500rpm and be a pain in the booty to start. I am ok if someone even says hey dumb a$$ go look at this table or these tables and figure it out. I have been dinking with this for few weeks now and just looking for ideas on where to look for get it running close to normal so I can do the auto tune setup with the wideband.

    Kevin

    TroyZ06.ctz

  2. #2
    Joe (Moderator) joecar's Avatar
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    Hi Kevin, an airleak would cause the idle rpm to go high like that.

  3. #3
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    That was my first thought, however it did this with my stock parts. 6.0 stock heads and cam, ls1 intake and injectors...
    I have literally poured brakeclean everywhere trying to find airleak. Not that it probly matters but watching my afr its 14.x to 19.x

    Sent from my SAMSUNG-SM-N910A using Tapatalk

  4. #4
    Joe (Moderator) joecar's Avatar
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    What PCV plumbing do you have...?

  5. #5
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    Like old school setup. Filter at the valve cover and capped off on the intake manifold.

    Sent from electronic life sucking device.

  6. #6
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    Looked at it again just to make sure.
    Drivers side has the valve and a mini filter on it. Passenger side goes out of valve cover to throttle body. Nothing in valley cover.

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    Last edited by sparkinak; June 24th, 2016 at 04:26 AM.

  7. #7
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    What valley cover?

  8. #8
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    What brand of 100MM DBC? is there an adapter plate on it?

    Are you sure it's making a good seal with the LS3 intake? Those intakes were DBW from the factory so I am curious if there is a mismatch in this area allowing air in?

    I know the FAST intake had this issue with there manifolds with certain brands of Throttle bodies.

  9. #9
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    I lied, holley 90mm and it bolts right up to the stock ls3 intake.

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  10. #10
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    The only problem id have with the bad fit to ls3 is i had this same problem before with all ls1 stuff but same tb.

    Sent from electronic life sucking device.

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