MISFIRE

  • Tiny
  • struxgl
  • Chevrolet

I SAW A POSTING ABOUT SOMEONE HAVING TROUBLE WITH MISFIRE ON #5 CYCLINDER ON A 1999 CHEV TAHOE. DO YOU KNOW THE OUTCOME OF HIS PROBLEM?
ALSO, HOW DO I TAKE A VACUM READING ON MY 1998 CHEV TAHOE WITH A 5.7 VORTEC ENGINE? WHERE DO I SCREW IN THE VACUM GAUGE?

Sunday, December 3rd, 2006 AT 9:05 PM

3 Answers

  • Tiny
  • hyknrd
  • Member

Not sure about the outcome of the other guy. A vacuum test is generally done with the engine warmed. You need a vacuum source(hose or pipe) from the intake manifold to hook to the vacuum gauge. All vacuum gauges I've used haven't threaded into anything, just hooked up by a vacuum hose. Plug whatever you disconnected.
At idle the gauge should be steady at about 15-20 inHg. Rev the engine and let off. The gauge reading should drop and then return to normal. If you have a misfiring plug the gauge reading will occasionally drop about 1-5 in. Hg.
Any other readings will let you know any other aspects about the conditon of the engine.
Hope that helps

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Monday, December 4th, 2006 AT 5:12 PM
  • Tiny
  • aripekadebi
  • Member

I had my check engine codes checked today. P1281, P0108, P0320, P0351, P0300, P0301, P0303, P0420, P0306, P0307 are the codes that were displayed. I am wondering what your point of view is concerning the amount of codes and what to do to repair.

Thank You for your time.

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Thursday, December 15th, 2011 AT 3:38 AM
  • Tiny
  • Jacobandnickolas
  • Expert
  • 68,315 posts

There are many that deal with misfires. It could be fuel problems, plugs, coil, internal engine issues.

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Monday, January 30th, 2012 AT 1:00 AM

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