high idle 2000rpm

J

jfields1977

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Jan 12, 2007

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#1

• Jan 12, 2007

• #1

I have a 1990 5.0 manual trans. When I start the car it idles at 2000 rpm and stays there. I have noticed over the past few weeks that at a stoplight the car would stay idling fast then drop to normal. I have replaced almost everything on this motor and am stuck. I recently replaced the IAC as I was told this was for sure the problem. I have no manifold vacuume leaks the IAC is new, MAS is working, TPS is calibrated and working. Doesn't seem to be a clutch issue. I adjusted the idle screw on the throttle body and brought the rpm down for a minute but when I restart the car it is hard to start and idle creeps back up to 2000. please help as this is my daily driver.

 

85ragtop

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#2

• Jan 12, 2007

• #2

Is it running rich? When my O2 censer went bad it ran rich and idled very high. Have you tried pulling codes?

 

J

jfields1977

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Jan 12, 2007

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#3

• Jan 12, 2007

• #3

will there be codes if the check engine light is not on?

 

85ragtop

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#4

• Jan 12, 2007

• #4

In my T-Bird the light never came on. It had a bad O2 and a bad EGR and I never did see the light come on. It can't hurt to try.

 

J

jfields1977

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#5

• Jan 12, 2007

• #5

Do you have to reset the computer when you replace the IAC? I disconnected the battery and seems to idle lower.

 

85ragtop

BTW, I like dudes.

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#6

• Jan 12, 2007

• #6

Did it drop a lot? Mine always idled around a 1000.

 

HISSIN50

"How long does it take to get help in here?

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#7

• Jan 12, 2007

• #7

With a hot engine, what happens if the IAC electrical connector is disconnected? What RPM does it idle at?

Though you said you checked everything, it still sounds like a manifold vac leak.

Also, for ideas and tips (though not directly related, a lot of the tutorials would apply), see Jrichker's idle surge sticky.

Good luck.

 

jrichker

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Jan 13, 2007

#8

• Jan 13, 2007

• #8

You guys with idle problems could same a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first post has all the fixes, and steps through the how to find and fix you idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.