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Can the Cat Cause misfire?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BigBadBowTie, Apr 27, 2000.

  1. BigBadBowTie

    BigBadBowTie 1/2 ton status

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    First off I do own an 86 Blazer. But since you guys always know the anwsers I still ask on my other rides.
    My wifes 92 Full Size has had a miss in for weeks. We changed the cap. rotor, coil, plug wires & plugs. Checked the computer no stored codes. Took it to a shop for a diagnostic test, found nada, except it was running to cool so we put the proper thermostat in it & some fuel cleaner. It misses pretty hard when idleing with the A/C on. It still misses with it off, but not quite as bad. It is much worse at loewer RPMs, usually clears up with a push of the gas, & hardly noticable at highway speeds. We bought the truck in Dec, the records show the fuel filter was replaced in Sep 99. We started noticing a sulpher smell on the highway which I belive is a bad cat, if so could this contribute or flat out cause my miss? Thanks in advance, let me knop if you want any other info on it...

    Rick

    Rick
    86 K-5
    http://www.coloradok5.com/RMcPherson.htm
     
  2. jmpd

    jmpd 1/2 ton status

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    A good muffler shop can point a temp gauge at the cat(during nornaml driving conditions w/o turning the engine off) to see if it is running the right temp(they have done this for my Toyota, Acura and Blazer and each time were able to tell me if it was the cat or something else), you can hit the cat when it is cold and see if you hear anything loose. The shop can do this when it is hot. My buddy owns/works at a shop and can tell right away if it is the cat.

    Good luck
    Michael
     
  3. jmpd

    jmpd 1/2 ton status

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    PS
    are coming to AZ meeting 4-30-00?

    See post
     
  4. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    A plugged cat can cause a host of problems.........One of them being misfire. Have you checked your module? It could be that, too.
     
  5. rich

    rich 1/2 ton status

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    You could also be smelling the cat because the engine is running rich or is misfiring. When the cat is "working harder" because of the increased emissions from a rich condition or misfiring, it can stink.

    Have you had any carb work done to it?

    One relatively easy way to check is to unhook the exhaust at the manifolds or somewhere else before the cat, and see if that fixes your problem. If so, then you know it was the cat.

    Richard
    '76 K-5 Blazer
    '90 K-5 Blazer
     
  6. BigBadBowTie

    BigBadBowTie 1/2 ton status

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