1998 GMC 1500 Misfire
5

Asked by LocoSmith Aug 17, 2017 at 04:37 PM about the 1998 GMC Sierra 1500

Question type: Maintenance & Repair

After taking a 3 hour round trip in June, my truck began to misfire on the way
home, so I had to keep it revved to keep it started.  Initially, we did a full tune
up (spark plugs, plug wires, cap, rotor, oil, antifreeze, etc.)  This didn't fix the
problem and it turned out to be a cylinder 7 misfire.  The head was removed
and reviewed and no cracks were noticed.  It was put back together and ran
smooth until a couple weeks ago when it started misfiring heavily on the first
drive each morning.  It didn't seem to do it as much after that first drive each
day.  We replaced the plug wires and spark plugs thinking it may be defected
parts.  Nonetheless, it was not.  Cylinder 7 continues to misfire based on the
spark plug residue.  Please give me any and all recommendations.

2 Answers
22,630

Guru9FSV8 answered 7 years ago

Gasket not sealed in the area of #7. When heats up it seals. Look this up on these gm products. Manifold gasket?

2 people found this helpful.
Mark helpful

GuruC9VVG answered 5 years ago

The gaskets are fine. No compression problems - plugs are new & good. The engine runs great - just the damn misfire problem.

Mark helpful

Your Answer:

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