Question about 2002 GMC Sierra 1500
2005 gmc 2500hd p0300 multiple cylinder misfire
Posted by Anonymous on
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Posted on Jan 02, 2017
Check the intake manifold gaskets for leakage. It will tend to run rougher in the morning when it is cold. Check for vacuum leaks on any hose connected to the intake plenum too.
Posted on Dec 13, 2009
SOURCE: when i connect my detector
mar82is, Mario, Yes a PO300 code is for random misfires. This is an issue with the spark plugs, wires, and coils. What you should do is to pull all the wires, one at a time, and inspect the terminals that connect to the spark plugs and the coil. If they are corroded then replacing these will help to alleviate the problem. Also check the spark plugs. See if they are wet and smell like gas. If so then this will be one of the misfiring plugs. A properly firing spark plug will have a gray color to them. If they are black and sooty then you should replace them. To check the coils, what you can do is purchase an in-line spark tester. You will find these at any auto parts store and they are not expensive. Place the tester on the spark plug and reconnect the wire to the tester and watch the light as it flashes. Should you see any gaps in the time that the coil fires then you have a bad coil and this will need to be replaced. DO NOT try to connect this tester with the engine running. It is rare, but the fuel pump will cause this condition as well. This will be from a weak pump or a clogged fuel filter. What to do here is, If you have one, connect a fuel pressure tester to the schrader valve on the fuel rail and watch for any discrepancies in the pressure as the engine runs. If there is, then I would start with the filter because the pump is in the tank and this will have to removed from the vehicle to replace it. Good luck with this.
Posted on May 16, 2011
If spark plugs and wires are done and it doesn't have a dead miss under load, usually it is the crank sensor acting up. It is a colon tab in all repair manuals
Posted on Mar 02, 2012
SOURCE: P0300 Trouble Code
Those 2 codes together usually mean there is a vaccum leak(the intake is getting air that is not metered through the mass airflow sensor).Look for PCV and vaccum lines loose(you might have got it by repositioning the air cleaner)
Posted on Apr 15, 2012
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