3G Eclipse Fast Idle

Widgmaster · Nov 3, 2019

I have been trying to diagnose a fast idle problem on a 2001 Mitsubishi Eclipse Spyder GT V6. I do not believe I have a vacuum leak . I read an article/video about placing your hand over the throttle body and the motor should die or if it runs it`s sucking air from some where else. Sure enough my car will stall. When I disconnect my mass air flow sensor the car will run at normal operating rpm and I can even put it in gear with the brakes on and rev it up . Again I`m told that the car should die. The idle set screw is at its lowest point so I am completely baffled . I have replaced the mass air flow sensor with no luck. Replaced the throttle position sensor with no luck. Please help...
P.S I did add a AME Cold Air Intake and new vacuum lines but had the problem way before this.

1990TSIAWDTALON · Nov 3, 2019

Get a spray bottle with water ( you can use other fluids but water isn't flammable).
Start the car and spray around the throttle body area and ANY suspect areas for a vacuum leak. I would hook up a vacuum gauge and monitor it. If you squirt water close to a leak, you should notice a change in the motors Rpms. If that happens, focus on the area you sprayed. I have used brake parts cleaner also, and the motor will rev if it finds a vacuum leak, which is what I suspect.
Make sure the intake is tight. I think they are all in the middle of the motor if I remember right.
Best of luck in chasing that fast idle.
What is "fast" and what is "normal"?
Marty

Widgmaster · Nov 3, 2019

I have tried the spray thing with propane and quick start and found no leaks. ( that's not say there isn't any ) but I found nothing. This car idles at 2 grand and the manual says 800/1000 . My Misbitchy creeps down the road at 40k without my foot on the pedal.

Cherry · Nov 3, 2019

Throttle cable too tight maybe? I dont know if the 3g has a point for idle surge, but for a 1g its 1500. Once it reaches that point the computer will cut fuel to the engine until the RPM comes down then cut the fuel back on and it cycles. With a throttle cable that is too tight it doesnt happen since the computer is getting a signal that the throttle plate is open and to not cut fuel, or at least that is my understanding. 2k sounds like it would be past that threshold if it has one, check for vacuum leaks and check the throttle cable adjustment.

Widgmaster · Nov 3, 2019

I have checked the throttle cable making sure it returns to it seated position but you gave me an idea...I have never checked to see if the throttle plate is still open . I will remove the air intake and see.

1990TSIAWDTALON · Nov 3, 2019

Idle stop screw is another thing that will hold the idle up besides a cable that is too tight.

Cherry · Nov 3, 2019

It could be that too. I just finally got done fixing my idle, months of messing with it, it can make you pull your hair out because it isnt working right and there is a long list of things it could be.

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3G Eclipse Fast Idle

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