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Thread: 1989 chevy 1500 5.7 timing wont advance

  1. #1
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    1989 chevy 1500 5.7 timing wont advance

    i have a 89 Chevy 1500 with a tbi 350 it wouldn't start one day so i replaced the ecm still no start. ended up being the pickup in the dizzy. so i pulled it and put it back in the same way same spot. will run decent with the bypass wire unhooked but when you clear it and hook it up it starts and starts popping and running like ****? anyone know what's goin on? i need help!

  2. #2
    Senior Moderator chevychase's Avatar
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    You replaced ecm.. computer was it a new one? What is timing at when timing wire connected? What is it at disconnected.
    Try cleaning all the ecm grounds at thermostat housing. Is vacuum at map connected?

  3. #3
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    not a new one computer but have tried my buddies with the same numbers. timing with wire plugged in is everywhere timing with it unplugged is 0 and never moves. i have timed 100 of these and never any trouble but imagine something would go wrong on my own truck. my ground strap from my head to firewall is broke but i have 2 block to frame grounds. could that be problem? and map Ame egr and tps is working. i have no idea. im tired of having to drive it advanced by ear with wire unplugged get's 4 mpg and decent performance. anyone know whats goin on?

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    Senior Moderator chevychase's Avatar
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    . Start all over get # 1 to tdc... look at rotor button pointing at # 1 plug wire.. Make sure it is #1 plug wire.
    Adjust if not. Then start truck check timing.. if off disconnect timing wire located at black box on passenger side cowl.. tan with black stripe.
    Set to 0 degree . Shut truck off reconnect wire .. tighten dist down. Crank truck see what you have. Fix the broke ground... clean grounds at thermostat housing.
    You are getting a check engine light when wire not connected? Are you using a adjustable timing light make sure you have it set right.
    Check for play in harmonic balance r... This will get timing off. Make sure map is connected to vacuum. Esc connected. Put your original ecm back.
    Maybe popping pinging bad enough being picked up by knock sensor ecm trying to adjust for it. This is all i can think of right now .. if i come up with something else let you know.

  5. #5
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    got it to run hale decent with timing wire hooked up. great performance runs better than ever but back fires when idling down after giving it gas? it has headers and no 02s could that cause it?

  6. #6
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    when i timed mine and it didnt advance i had a blown fuse under the dash ...changed it and evreything good ....not sure if this your problem but hey dont hurt to look

  7. #7
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    backfire on decel.....any exhaust leaks?
    4 wheels move the body
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    Snow is a lot like religion and a lot like sex....you never know when you are going to get it!....or how much you will get

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