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intermittent high idle 6.0 gas

Discussion in 'Chevy Trucks' started by ontario026, Dec 31, 2012.

  1. ontario026

    ontario026 Senior Member
    Messages: 228

    My 2000 silverado 2500 6.0 has started occasionally idling at about 1100 rpm instead of it's normal 600rpm

    Any ideas??
  2. shovelracer

    shovelracer Senior Member
    Messages: 525

    Defroster on, engine light, or noises?
  3. chevboy167

    chevboy167 Member
    Messages: 96

    Hi. Does it idle high at cold start or any temp? Check for vacuum leaks/ lines broken? How many miles on truck or hrs on engine? Is the SES light on dash? I just replaced intake gaskets and both knock sensors with wire harness on my '99 1500 Silverado. She was hunting up & down for steady idle at cold start till motor heated up to 180* then smoothed out to normal. I retightened down the intake bolts just a half turn per bolt and that helped. So that told me intake gaskets were leaky/sucking raw air causing a lean condition on both banks. All is perfect now. Made a huge difference on how it runs now! Smooth like the day i got her.
  4. ontario026

    ontario026 Senior Member
    Messages: 228

    no check engine light on, about 270K kilometers on the clock... It did it the other day while plowing, and stayed idling high most of the day, but seemed to act normal for the last hour or two that I was out..... Then today all seemed fine on my way to work etc until I did a 120 Kilometer an hour run down the highway on my way home (blade still on the truck) on the hwy the temp gauge came up a little, then the clutch fan kicked in, and gauge dropped to normal, but when I exited the hwy and crossed town to get home I noticed the elevated idle again.... Power wise it feels like normal, no noticable loss in power or misfire etc....

  5. chevboy167

    chevboy167 Member
    Messages: 96

    Another idea may be the EVAP VENT CONTROL solenoid under the truck. Some are under & between the cab and box on the drivers side or located at the rear by the spare tire. Its a square box or round puck with a large vacuum tube and a 2 wire plug harness running to it. Inside is a foam filter that gets clogged up with road dust and grime. It can be taken apart with care, cleaned and reinstalled or replace the whole unit with new. That helps mine alot because i live in country on gravel roads. However i know not all Chevys have this solenoid. Depends on the emissions build of the vehicle i believe.