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Thread: 2003 silverado 6.0 misfire issue

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    2003 silverado 6.0 misfire issue

    I have a 2003 chevy silverado and it wont seem to run rite. I looked it up and it says its a misfire. What could be causing this problem? The truck sits most of the time with fuel treatment ran threw it.

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    Senior Member greencamaro1981's Avatar
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    u look at the wires? i had a rabbit eat a couple of my plug wires, check plugs, when u run it does it get really hot and clean itself out if not then go drive it 20 miles on the interstate to get it good and hot and let it all burn off

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    Senior Moderator chevychase's Avatar
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    Are you getting check engine light? You said you looked it up ... is this because of light.
    If your not getting a light can narrow problem down some.

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    Senior Member 87c10slammer's Avatar
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    if you let some types of fuel treatments sit in the system for a long time then they will break down the fuel lines and filter and cause your injectors to clog.. what type are you using... also running it in every tank will cause issues as well. it doesnt burn right and fouls out plugs at a rapid rate specially in newer vehicles.. stuff like staybil is ment for older carbed engines that sit over the winter and your only supposed to leave a gallon of gas in your tank and then when it comes time to drive the car again your supposed to fill it up to delute the treatment before you run it through the system.. its more hassel then its worth.. i have 15 old cars i winterize every year.. never have used any kind of fuel treatment.. i just drain the tanks and flush the carbs out..

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    Senior Member zombie1969's Avatar
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    Diaging a missfire takes some time.First swap the plug with another cyl thats not missing and see if it changes.If not swap a wire and see if it changes to the other cyl.The next thing would be to swap the coils from one cyl to another and see if it changes.Next would be changing the injecter or just replacing it because its the most common cause of a miss in your aplication due to clogging from crud in the fuel.Its possable but unlikely the cause goes beyound that point from experiance and doing all this takes less than hour with a good scan tool with live reedings.
    Sent using Boost mobile 4g htc evo.

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    I m getting a flashing engine light and the code reader has a p0300 misfire. at cylinders 5 and 6

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    Senior Member 87c10slammer's Avatar
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    flashing CEL means cadistophic failure.. basically if you keep driving it like that the truck is gonna shut down..

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    I swaped the coil packs around check the plug wires and cleaned the mass air flow sensor and etc. I dont know what else could be wrong with it? What do you all think? Any clues please help thanks

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    Senior Member 87c10slammer's Avatar
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    i stated my opinion above..

    Quote Originally Posted by 87c10slammer View Post
    if you let some types of fuel treatments sit in the system for a long time then they will break down the fuel lines and filter and cause your injectors to clog.. what type are you using... also running it in every tank will cause issues as well. it doesnt burn right and fouls out plugs at a rapid rate specially in newer vehicles.. stuff like staybil is ment for older carbed engines that sit over the winter and your only supposed to leave a gallon of gas in your tank and then when it comes time to drive the car again your supposed to fill it up to delute the treatment before you run it through the system.. its more hassel then its worth.. i have 15 old cars i winterize every year.. never have used any kind of fuel treatment.. i just drain the tanks and flush the carbs out..

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    I added fuel treatment to it today and put 20 miles on it so it get mixed up and the engine light still flashes and runs rea choppy and has a misfire on cylinder 5 and 6

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