2002 GMC Sierra misfire

2002 GMC SIERRA
104,000 MILES • V8 • 2WD • AUTOMATIC
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TGAONA
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  • 1 POST
I have a 2002 gmc sierra 1500 5.3L and the #1,and#7 cylinders are misfiring and I have changed the fuel filter,ignition coils,spark plugs and wires,mass air flow sensor.And it is still showing misfire can anyone please help?
Jul 7, 2008 at 2:36 PM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,988 POSTS
A misfire in a specific cylinder should lead you to check the spark plug, fuel injector and compression on that cylinder

Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
Jul 7, 2008 at 2:45 PM
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