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1988 GMC Sierra Engine miss

Tiny
MIKE.JANES
  • MEMBER
  • 1988 GMC SIERRA
  • V8
  • 2WD
  • AUTOMATIC
  • 125,000 MILES
I changed plugs, wires, cap, and rotor. Engine still misses. At idle you can hear it missing, and it makes a popping sound in the exhaust. By pulling plug wires one at a time, each one seems to slow the engine down and it idles rougher. Engine misses while idling or going down the road. It also misses under acceleration whether mild or wild.

Any Ideas?
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Wednesday, May 5th, 2010 AT 8:27 AM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Engine running rough or misfiring can be cause by the following:

1. Defective spark plug.
2. Inadequate spark/coil, defective spark plug wire.
3. Lack of compression
4. False air leakage.
5. Faulty fuel injectors.
6. Insufficient fuel pressure.
7. Contaminated fuel.
8. EGR valve that is leaking.
9. Oxygen sensors.
10. Throttle position sensor
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Wednesday, May 5th, 2010 AT 9:14 AM

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