May 132015
 

I have a p0305 misfire . I have changed the cap rotor distributor plug wires spark plugs and the spider injection system . It has 100 psi in the #5 for compression and I’m running about 60 psi for fuel . I can’t figure it out. I also checked the valves they are working good as well .

  One Response to “99 chevy suburban”

  1. Clogged EGR can sometimes cause this or a vacuum leak, usually around the intake. If it still has dex-cool coolant(orange) I would put money on an intake leak.

    Possible causes
    – Faulty spark plug 5
    – Clogged or faulty fuel injector 5
    – Faulty ignition coil 5
    – Fuel injector 5 harness is open or shorted
    – Fuel injector 5 circuit poor electrical connection
    – Ignition coil 5 harness is open or shorted
    – Ignition coil 5 circuit poor electrical connection
    – Insufficient cylinder 5 compression
    – Incorrect fuel pressure
    – Intake air leak

    The P0305 code means that the cylinder 5 is misfiring or is randomly misfiring. Start by checking for intake leaks an if no leaks are found the next step is to replace the spark plugs on cylinder 5. If the problem persist more tests needs to be done to diagnose problem, see “Possible Causes”

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