99 Yukon 5.7l

Tiny
GORDON777
  • MEMBER
  • 1999 GMC YUKON
  • V8
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
99 Yukon, runs great, but misfires when at low throttle settings at hiway speeds. No codes, recent major tune up. 170,000 miles.
Friday, January 14th, 2011 AT 2:07 PM

1 Reply

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

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

1.Defective spark plugs
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.
11.Manifold absolute pressure sensor
12.Mass Airflow Sensor
13.Idle air control valve

Note: If it doesn't apply disregard it-
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Saturday, March 19th, 2011 AT 12:17 AM

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