1993 Pontiac Grand Prix

1993 PONTIAC GRAND PRIX
180,000 MILES • 6 CYL • 2WD • AUTOMATIC
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TWESTER
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What makes my car idles at an high rpm and then drop? It has the 3.1 multi port fuel inj mtr in it. I have changed out the map sens and tps as well but is still does it...
Oct 17, 2010 at 8:41 PM
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JDL
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It will do that with a cold engine. If the hvac is turned on, the rpms may be higher. There are other issues that may cause the rpms to go up?
Oct 18, 2010 at 12:10 PM
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TWESTER
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it does it when the car is warm as well... however what could be some other reasons could cause it to idle up and down when cold or warm? there are no vac leaks put new map sensor on it and also has good fuel psi. Could it be the ECM perhaps and if so where is it located?
Oct 18, 2010 at 10:30 PM
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JDL
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Passenger side fender panel, underhood, near strut tower.
Oct 19, 2010 at 9:14 AM