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Thread: Misfire when cruising

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    pat d's Avatar
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    Default Misfire when cruising

    OK did a huges intake swap headers and rockers 1.7 new plugs wires cap rotor now i have a misfire when im cruising at about 1400-1500rpm's and backfire out of tail pipe did not think i had this before what can i ck for also when i start it up sometimes when starting it will bumble like i have a big cam no throttle response will shut off if i give it gas , i turn it off then back on and everything is normal what else do i ck for ????

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    First thing I would look at is fuel sync.
    Also check valve adjustment.
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    pat d's Avatar
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    thanks kota360 i did not do the work myself the guy that did it said the timing was off so he adjusted it and i think thats part of my problem and if valves are to tight cause the backfireout of exhaust.How do you set the full sync

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    You need a Snapon scanner to set the fuel sync, but if you didn't put a cam in it then you shouldn't have to worry about that. Check and make sure the distributor cap is sitting in the right spot.

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    Quote Originally Posted by pat d View Post
    thanks kota360 i did not do the work myself the guy that did it said the timing was off so he adjusted it and i think thats part of my problem and if valves are to tight cause the backfireout of exhaust.How do you set the full sync
    If he moved the distributor you're screwed! You need a scanner to reset it. It changes the fuel sync, not the timing.
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    pat d's Avatar
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    what snap on scanner does he need any specific model he has some kind of tablet i know he moved the distributor because he said the timing was of so he moved it a little bit i feel like this is my biggest problem

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    If you don't mind spending a little cash, go to the dealer or a reliable shop that you trust.
    Ask them to set the fuel sync.
    They should have the right scanner(the dealer ship will for sure).
    The fuel sync is set by turning the distributor.
    The timing is set by the computer.
    Once that is set, the truck should run a 100% better.
    Edelbrock Magnum heads, Harland-Sharp 1:6 RR, Jomar Performance Ultra-Lite Stud Girdle, SoutheastPerformance Sheet Metal Valve Covers, Custom Hyd Roller from Reed Cams, Mopar M-1 2 Brl Intake, Hughes Stage 1 TB, JBA SS Headers, Jacobs Electronics Pro Street Ignition System and Wires, MBRP 'Cuda Style Exhaust, Western Chassis 2" drop front and rear, Edelbrock IAS Shocks, Terry DeLong Pro-Glass Shaker Hood

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    Quote Originally Posted by pat d View Post
    what snap on scanner does he need any specific model he has some kind of tablet i know he moved the distributor because he said the timing was of so he moved it a little bit i feel like this is my biggest problem
    Quote Originally Posted by kota360 View Post
    If you don't mind spending a little cash, go to the dealer or a reliable shop that you trust.
    Ask them to set the fuel sync.
    They should have the right scanner(the dealer ship will for sure).
    The fuel sync is set by turning the distributor.
    The timing is set by the computer.

    Once that is set, the truck should run a 100% better.

    This is an issue. If he did all the work. Then you may need to recheck all the work.

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    pat d's Avatar
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    so no matter what i do with distributor now will not make a difference? so the computer reset is what i need

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    The computer is looking for the distributor to be in one very specific spot. Turning the distributor does not adjust timing like on older vehicles, but will completely screw your computer's ability to set timing. When a dealer (or someone with a good Snap-On Scanner) sets the fuel sync they set the distributor back to the spot the computer is looking for; if it's off even a little things go sideways.

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    There’s a YouTube video of a dude that plays a dude that looks like another dude that uses a Snap-On tool to do the fuel sync on a 5.9 Magnum. From that I went to the local greaser shop that I know and they had the Snap-on tool, he’s a cool 50’s dude and let me use his Snap-On tool to set the fuel sync on mine. He had no idea what I was talking about but was interested. I showed him how and we managed to get it set. No charge so I dropped off a case of beer.

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    Ok got it fixed fuel sync was set at 17 backed it down to 1-0 . Runs smooth and starts up much better now thanks for all the help and directions

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    Quote Originally Posted by pat d View Post
    Ok got it fixed fuel sync was set at 17 backed it down to 1-0 . Runs smooth and starts up much better now thanks for all the help and directions

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