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Mike S.
Mike S., ASE Certified Technician
Category: GMC
Satisfied Customers: 6925
Experience:  GMC N.A.I.S.E. Certified Auto-Mechanic
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I HAVE A 2001 GMC SIERRA 6.0L WITH A CYL 7 MISFIRE. I HAVE

Customer Question

I HAVE A 2001 GMC SIERRA 6.0L WITH A CYL 7 MISFIRE. I HAVE REPLACED PLUGS, WIRES, INJECTORS, COMPRESSION TESTED, SWAPPED COILS, NEW FUEL PUMP, FUEL FILTER, FUEL PRESSURE REGULATOR. DONT KNOW WHERE ELSE TO GO WITH THIS THING! PLEASE HELP
Submitted: 7 days ago.
Category: GMC
Expert:  Mike S. replied 7 days ago.

Hi, I am Mike, welcome. I'm reviewing your question.

Expert:  Mike S. replied 7 days ago.

Perhaps there is a worn down cam lobe on #7, check the cam lobe lift on each intake and exhaust valve and compare them to the cylinder next to it.

Customer: replied 7 days ago.
AT SOME POINT DURING THIS PROCESS I HAD THE VALVE COVER OFF TO CHECK FOR BROKEN SPRING AND HAD THE ENGINE TURNED OVER AS I WATCHED THE VALVES WORK. I KNOW ITS NOT MEASURING THEM BUT THEY BOTH LOOKED AND MOVED FINE.
Expert:  Mike S. replied 7 days ago.

Then there must be a vacuum leak there at #7.

Did you check to make sure #7 fuel injector does have a pulse when cranking?

Customer: replied 7 days ago.
7 HAS A PULSE WHEN CRANKING. BY VACUUM LEAK ARE YOU TALKING INTAKE GASKET?
Expert:  Mike S. replied 7 days ago.

Yes. Intake manifold gasket.

Expert:  Mike S. replied 7 days ago.

Would you like the instructions for replacing the intake manifold gasket?

Expert:  Mike S. replied 5 days ago.

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