1999 Pontiac Grand Am Car Pulsates

ENCHANTM1NT

MEMBER
1999 PONTIAC GRAND AM
4 CYL
2WD
AUTOMATIC
163,254 MILES

When driving the car the rpm gage pulsates when you let off the gas if you come to a sudden stop the idol speed goes below 800 And the car almost dies. While setting still the idol does not pulsate but is low

Wednesday, February 3rd, 2010 AT 1:31 PM

4 Replies

MERLIN2021

MECHANIC
17,250 POSTS

You may have a vacuum leak, get a can of spray Throttle body cleaner, 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! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody
Keep the spray away from the exhaust manifolds!

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Wednesday, February 3rd, 2010 AT 1:33 PM

ENCHANTM1NT

MEMBER
3 POSTS

Changed the idle air control valve and it still does it, The guys at advance told me it could be the EGR valve but it cost $175, After spending $83 for the air control valve I thought I would ask first if anyone thought it would work

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Wednesday, February 3rd, 2010 AT 5:54 PM

MERLIN2021

MECHANIC
17,250 POSTS

Did you spray with the cleaner? It is probably a vacuum leak, spray all around the intake where it bolts to the block, intake gaskets can do this. EGR will normally set a code, and turn on the service engine light. If it's on have the code(s) read and post all found here.

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Wednesday, February 3rd, 2010 AT 7:16 PM

ENCHANTM1NT