1992 GMC Sierra engine idiling problem

1992 GMC SIERRA
300,355 MILES • V8 • 4WD • AUTOMATIC
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JODEEMON
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Hello
I have a question about a 1992 GMC 1 ton with a 454 motor.
When I start the motor it really idles funny the idle goes up and down sometimes the engine even stalls and when it warms up the idle is fine and stays at a constant level. Ive changed the distributor cap and put new plug wires on it. The idle air control valve has been replaced and a new O2 sensor as well as some other sensors have been changed. I was just wondering if a vaccum leak could be the problem? or could it be something bigger?
Jun 16, 2008 at 1:26 PM
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LEGITIMATE007
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It could be vacuum, I would check the pcv valve and my map sensor along with the mass airflow sensor. you can also do the little brake clean test, just mist alittle around your intak manifold and vacuum hoses, and obviously, if the idle changes then that is where your vacuum leak is. you can use throttle body cleaner(preferably)too.
Jun 16, 2008 at 2:16 PM