1988 Pontiac Firebird Idling at stop when car is warm

1988 PONTIAC FIREBIRD
100,000 MILES • V8 • 2WD • AUTOMATIC
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NUNYA522
  • MEMBER
  • 2 POSTS
The car starts and idles and runs great.But once its warmed up after going down the road and you come to a stop the rpms start fluctuating on the tac. but only if its in gear.You can put it in nuetural and it starts idling fine at 400 to 500 rpms. It has no codes come up. Its mulit port fuel injected.
Feb 24, 2008 at 8:56 AM
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MERLIN2021
  • ✓ASE Certified Mechanic
  • 17,250 POSTS
  • ASE Certified Mechanic
even 400-500rpm is low! 7500-800 is the normal idle,
You may have a vacuum leak, get a can of spray gumout, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! The other thing is, service engine soon light, is it on?
Feb 24, 2008 at 8:59 AM
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NUNYA522
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  • 2 POSTS
No the check engine light is not on.
Feb 24, 2008 at 9:11 AM
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