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Check engine light came on????

Discussion in 'General Chevy & GM Tech Questions' started by vncj96, May 11, 2009.

  1. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    My suburbans light came on when it was idling at the gas station when I came out it was on. I have noticed a slight chunky vibration (if that makes sense)over the last week or so. When I got to work, I opened the door to listen to the exhaust and it was like i had an old muscle car with a big cam and the note and 500 RPM was very chunky but the engine seemed to be running smoothly and power seemed fine while on the highway. I am getting the code read tomorrow but just wanted some opinions
  2. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    Well its P0304, the oooooold number four cylinder misfire huh! I reset the CEL and on my way home from oreillys it didnt come on, so after it cools I will do the norm I guess check the plug, wire and distributer. The distributer is only a year old, the wires have been on since I bought the truck and the plugs are two years. Other then that any suggestions???
  3. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    That's probably where I'd start, too. Don't forget that it might also be a fuel system problem (in particular the #4 poppet valve might be going bad. They have been problematic).
  4. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    This is the first I have heard of a poppet valve:neutral:
  5. just change the wires and plugs you should be fine.
  6. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    I think poppet valves means regular car type valves. In older times there were sliding valves and all sorts of other ways to let in mixture and get out exhaust.They finally figured out that round valves/stems with a spring were the way to go.I think older valves spring steels broke frequently-hence the looking for other types of valves.

    Could be wrong on this,
    Charlie
  7. CarpenterGuy

    CarpenterGuy Epic Member 5+ Years 500 Posts

    our old car did this and it turned out to be a faulty plug wire, so i'm bettin git has to do with your plugs/wires.
  8. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    Hopefully some new wires will cure all
  9. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    Sorry, I get so used to this term, as often as it is discussed, that I forget that some people have no idea what a poppet valve refers to on these engines.

    The poppet valve mentioned is the type/style of fuel injector GM used on the late '90's CSFI (Central Sequential Fuel Injection) engines (small block V8's for the most part I believe). For whatever reason, these "injectors" don't wear very well. Of course, one symptom of a failed "injector" would be a misfire for that cylinder. GM has since redesigned the "injection spider" to use real injectors rather than poppet valves. I apologize for not explaining that in the first place.

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