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  1. #1

    Post 1997 Vortec 454 , very bad stumble and miss

    I have a 1997 C3500 with the Vortec 454 (7.4L) and it has a very bad stumble.It does it mostly when warm When driving normal ( light on throttle and no load) the truck drives fine but if you give it gas or if you have a load on its stumbles very bad and looses alot of power. It only does this on acceleration or going up hills. It also does it all the time in reverse. Its getting bad but i cant find the problem. Here is some stuff i checked and replaced:

    -Fuel Pressure : 59 PSI at idle 54 PSI at 3500 RPMS.
    -I changed Spark plugs, Distributor Cap, rotor. I didnt do wires because they were changed not that long ago and this doesnt seem like a bad wire problem since it is not constant.
    -I have a check engine light and its only saying bad crank sensor code , but i dont think its the crank sensor because crank sensors cause it to stall and not start, it starts OK . I am replacing crank sensor this week though.
    -Added Vavloline Fuel Injector cleaner.
    - THe truck has no bad codes besides the crank sensor.

    If i find the problem i will post it but i cant figure out what it is

  2. #2
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    Which code is it you are talking about. If it is cam shaft - crank shaft correlation, then it could be there is a bad sensor, worn timing chain, worn distributor pinion or simply the cam shaft retard needs to be adjusted.
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  3. #3

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    I dont remember exaclty what it said but it said something like Crank Shaft sensor . I will check tomorrow and post the correct code. I am also going to change the wires this weekend. I noticed that alot of people have been having problems with this engine.

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