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Thread: P0300 and P0303 code help

  1. #1
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    P0300 and P0303 code help

    I've got a 2003 S-10 with a 4.3L engine with 64K miles on it.

    It started to run rough today and shortly after that the check engine light came on. It ran very rough at idle but wasn't too bad going down the road. I went home and hooked up my scan tool and got a P0303 code. The cap and rotor were replaced about 2 months ago so I looked at the wires. The wires showed some wear so I replaced them. When I started the truck it ran a little smoother but was still rough. I got a P0300 code then. The truck is still rough at idle but not as much as before. It lacks power and the check engine light comes on every time I accelerate hard. I put a cheap autozone cap and rotor on it before so I got a new cap and rotor and tried it again. Then I got the P0303 code again. It seems to smell like gas too like it could be rich, and it sometimes hard to start. I bought a set of spark plugs to put in tommorrow since it probably needs them anyway.

    Anyone have and suggestions of what it could be or how to find out?

  2. #2
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    Re: P0300 and P0303 code help

    Lucky cly #3 the worst to get the plug out. I would only use genuine GM products, plugs, wires, cap and rotor if it were mine and it was stock. You may have a bad plug and pay close attention too #3 over the others. Something i have been seeing allot of lately is carbon tracking on the plug porcelain causing a misfire.
    03 S10 XTREME ON THE BOTTLE.
    03 S10 ZR5 CREW CAB DAILY DRIVER.
    94 S10 4WD. Sold
    IWTTMB!

    ______________________________________________
    SHI* IN ONE HAND AND WANT IN THE OTHER, SEE WHICH FILLS UP FIRST.

  3. #3
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    Re: P0300 and P0303 code help

    Hows the exhaust smell, kinda Eggish?

    Wonder if the Converter is to blame. I see its a truck that has a few years on it, and has little miles on it....thinking the converter could be plugged up.


    Jay

    If at first you don't suceed, cheat, repeat untill caught, then lie

  4. #4
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    Re: P0300 and P0303 code help

    ^Also a another strong possibility.^
    03 S10 XTREME ON THE BOTTLE.
    03 S10 ZR5 CREW CAB DAILY DRIVER.
    94 S10 4WD. Sold
    IWTTMB!

    ______________________________________________
    SHI* IN ONE HAND AND WANT IN THE OTHER, SEE WHICH FILLS UP FIRST.

  5. #5
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    Re: P0300 and P0303 code help

    The exhaust doesn't smell eggish, it smells more like raw fuel. When I get home from work tonight I'll do some more troubleshooting.

  6. #6
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    Re: P0300 and P0303 code help

    I changed the spark plugs tonight and the #3 spark plug was completely black. All the other spark plugs looked good. Once I got them all changed I drove the truck and got another P0303 cylinder #3 misfire. It was still rough at idle and doesn't have much power, it feels like it is running on 5 cylinders. Could this be the ignition module or crank sensor? Anyone have any suggestions?

  7. #7
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    Re: P0300 and P0303 code help

    I would like to think that you need to replace the fuel filter, it is also probable that you put in some bad gas, which is not too uncommon these days. I suggest a good gas dryer additive and see how it runs after that. also if you live in an extremly wet area check your coil wire that goes to the distributer I had a problem like what your experiencing and the wire was old and shot, but didn't act up till it rained

  8. #8
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    Re: P0300 and P0303 code help

    I just changed the fuel filter about 6 months ago. When I drove it after changing the plugs I put fresh gas in and put 93 octane in. It seems like the #3 cylinder isn't firing even with a new cap, rotor, wires, and spark plugs, but I'm not sure what could cause this?

  9. #9
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    Re: P0300 and P0303 code help

    well I can see I got here a little late. your on to something with the #3 cylinder. I am not sure where the lack of power stems from . but I think you will find it real quick.....

  10. #10
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    Re: P0300 and P0303 code help

    every time I change the oil , I get a new gas filter, mind you I use amsoil , so only change it two times a yr. you think maybe you are grounding out somehow on that #3?

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