1988 GMC Sierra Engine miss

1988 GMC SIERRA
125,000 MILES • V8 • 2WD • AUTOMATIC
Avatar
MIKE.JANES
  • MEMBER
  • 1 POST
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?
May 5, 2010 at 8:27 AM
Advertisement
Avatar
RASMATAZ
  • CAR REPAIR CONTRIBUTOR
  • 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
May 5, 2010 at 9:14 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.