chevy 350 5.7 in 1500 misfiring

Discussion in 'General Chevy & GM Tech Questions' started by chimp54321, Aug 23, 2011.

  1. chimp54321

    chimp54321 New Member

    Hi, I'm new to the forum and don't know a whole lot but am trying to learn. I have a 98 Chevy 1500 with a 5.7 350 in it and it is running really sluggish and is having misfire, service engine soon light is on. It started doing it when I was heading up a hill, it just started bogging and has been doing it ever since especially when I give it a lot of gas. I have replaced the plugs and wires as well as the fuel filter to no avail. I have been researching the common fuel intake problems with the motor and am starting to think I need to clean the injectors. It has 160000 miles on it and I've already changed a fuel pump on it. Does anyone have any good suggestions to try or ideas to what it could be. It seems to drive better I'm third gear as well.

    Thank you

    BASSIST Rockstar 100 Posts

    Did you also change the distributor cap and rotor or just the plugs and wires?
  3. chimp54321

    chimp54321 New Member

    I think I just changed the rotor but not the cap. Is it common for their to be problems with the cap?
  4. mfleetwood

    mfleetwood Epic Member 5+ Years ROTM Winner 5000 Posts

    Another cause could be the plugs. What type did you use? It is highly recommended to stick with AC Delco, as some other brands (even high quality ones) do not work with with our rides.
  5. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Try a new AC Delco cap & rotor
  6. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    Welcome to the club. As mentioned above us A/C Delco cap, rotor and plugs. As many of us on this site have found out, GM's seem to like A/C's spark plugs.
  7. chimp54321

    chimp54321 New Member

    Thank you guys for the advice. It seems strange that after changing all the plugs and wires and cap and rotor it is acting exactly the same way as before. Does anyone think it might be the timing or fuel intake?

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    You mentioned above that the SEL came on, If we knew what Trouble Code is causing the SEL to come on, it would help us in order to help you......right now were all taking a guess at what the problem is,

    A Random Mis-Fire could be one or more of the Following has Happened,
    • Faulty spark plugs or wires
    • Faulty coil (pack)
    • Faulty oxygen sensor(s)
    • Faulty fuel injector(s)
    • Burned exhaust valve
    • Faulty catalytic converter(s)
    • Stuck/blocked EGR valve / passages
    • Faulty camshaft position sensor
    • Defective computer
    You local Auto Zone O'Reilly's.....etc will at no cost to you Scan the Trucks Computer, and then you'll know what the problem might be.

  9. chimp54321

    chimp54321 New Member

    I just took it to advance auto and plugged it into the computer and it read that the camshaft sensor and both o2 sensors are both bad. I think I'm just going to try and replace those. Anyone have any suggestions or good how to posts? Thanks again you guys have been helpful.
  10. silveradotrailblazer

    silveradotrailblazer Epic Member 5+ Years ROTM Winner 5000 Posts

    Your truck has dual cats and four O2 sensors. When you say both O2's are bad do you mean the rear( after cat) o2 sensors?

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