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  1. #1

    Default 91 c1500 5.7L idle ok hesitates when in R or D with brake applied

    hello, New to this forum. i got 91 silverado 1500 with 5.7 issue im having is the engine stumbles a little whenever it is in R or D. At idle in Park or N the engine runs smooth no signs of hesitation. No code and /or light on. First found IAC valve getting stuck replaced it. issue got better but still there. checked MAp-ok Knock sensor-ok 02 sensor-new with a nice wavefor at idle. temp sensor-new, TPS- ok smooth wake form, new plugs and cap n rotor.....
    ONe thing i notice is that when i spray brake cleanner in the intake manifold gasket area, the 02 tends to pick up that extra fuel that i'am sprying. Any ideas or commomng problems anyone has gone through?? Thank you.

  2. #2

    Default

    If you are spraying carb cleaner on the intake gasket and the rpms are going up then it sounds like you have an intake manifold leak. You just have to be sure that none of the spray from the carb cleaner is getting into the Throttle body. If you are sure that it is not, then I would definitely say you have an intake leak. That may not be causing your issue, but it is a place to start.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  3. #3

    Default

    Quote Originally Posted by Pikey View Post
    If you are spraying carb cleaner on the intake gasket and the rpms are going up then it sounds like you have an intake manifold leak. You just have to be sure that none of the spray from the carb cleaner is getting into the Throttle body. If you are sure that it is not, then I would definitely say you have an intake leak. That may not be causing your issue, but it is a place to start.
    Thanks for replying, yes im 100% sure the gasket is leaking and yeah im not 100% conviced that is the main issue but know i need to get rid of any air leaks first. i should have it off in the next 10 mins thanks again.

  4. #4

    Default

    Habe you checked your trans fluid? I have seen trucks with low fluid cause stalling and rough idle when put in gear.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  5. #5

    Default

    Quote Originally Posted by Pikey View Post
    Habe you checked your trans fluid? I have seen trucks with low fluid cause stalling and rough idle when put in gear.
    You know what, that never crossed my mind. Definitely will look into that. Thanks!

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