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5.7 Vortec Stumble/Hesitation

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  • 5.7 Vortec Stumble/Hesitation

    I replaced my intake gaskets with the felpro kit last saturday and all went well besides a hesitation off idle and stumble/buck/jerk at cruising speeds (running about 1500-2000rpm). All bolts were torqued to spec. I have done a LOT of searching and found that several other people had this problem. When I pulled the dizzy, I marked the rotor to the dizzy, and the dizzy to the intake so Im pretty sure my timing is right. Distributor gear looked good. Ive narrowed it down to the EGR, bad ignition connections, spark plugs, timing, or fuel delivery issues. Tomorrow Im going to have it scanned for codes. Truck in sig with 124,000 miles. The stumble at speed seems to happen most often when I turn off the cruise and only happens about 3 or 4 times in a 10 mile hwy trip. Ran just fine before I replaced the gaskets and Ive looked under the hood while running at night and couldn't see any arcing. Any suggestions? Thanks.

    edit: Video at idle
    Last edited by SlvrdoHDmax; 12-02-2009, 11:34 PM.

    2005 2500HD>Duramax>EFI Live DSP5 by Punisher Performance>FASS Platinum LP>AFE Turbo MP>EGR Blocked>PCV Rerouted>Mild audio setup>4" Exhaust>Alligator Performance Race Fuel Valve>Edge Insight CTS

  • #2
    Re: 5.7 Vortec Stumble/Hesitation

    I had a similar issue but it was mainly at take offs. The truck would stumble and almost die, then take off like a bat out of hell. The MAF sensor was bad because it accumulated the oil from the K&N air filter. Just something you may want to check.

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    • #3
      Re: 5.7 Vortec Stumble/Hesitation

      Well I found my problem. My own dumb mistake.. Checked all my connections today and found that I didnt plug my cam sensor wire back into the distributor. Thanks for the help

      2005 2500HD>Duramax>EFI Live DSP5 by Punisher Performance>FASS Platinum LP>AFE Turbo MP>EGR Blocked>PCV Rerouted>Mild audio setup>4" Exhaust>Alligator Performance Race Fuel Valve>Edge Insight CTS

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      • #4
        Re: 5.7 Vortec Stumble/Hesitation

        Glad it was an easy fix. Important little buggers the cam and crank sensors. Mine threw a code for a while (never fixed it) until it flat out died on the road one day. Cam/crank Position Sensor code. It was because of the gear on the dizzy, it was so chewed up, the gears on one side were flat, and the other side they were half gone.

        Just FYI too, you can have the dizzy waaaaay off, and the computer will adjust the timing to an extent. Granted, 180 off it can't, but I set mine in the first time a tooth or two off (if I remember right, it was 27 degrees off) and it ran fine. Thank god for auto-tech class, and a 4 grand scan tool, which are some really sweet devices to play with.
        Mark

        1997 K1500 Z71, 14b SF, Bright Blue Metallic. 6" Superlift, 35" DC Crushers, 3/4 ton leafs. IRON BULL bumper, MM 12k Hyd Winch,
        1972 C-10 longbox/factory toolbox
        1972 C-10 shortbox stepside
        2008 1500 Z71 CCSB, wife's ride

        http://s107.photobucket.com/albums/m294/69-350/

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        • #5
          Re: 5.7 Vortec Stumble/Hesitation

          Thanks for the info. Almost asked the auto class teacher about it today before I checked it myself. I guess my timing must be right on then because when I set mine, I had it exactly on both my marks.

          2005 2500HD>Duramax>EFI Live DSP5 by Punisher Performance>FASS Platinum LP>AFE Turbo MP>EGR Blocked>PCV Rerouted>Mild audio setup>4" Exhaust>Alligator Performance Race Fuel Valve>Edge Insight CTS

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