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Cadillac Catera
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11 Posts
Discussion Starter #1
I have a 79 Eldog with the 350 Olds fuel injection motor. When I start the car, and its in park, the motor runs super, super fast!

I removed the breather and figured I would just turn the idle screw to slow the motor down a tad, then I discovered the idle screw cant be adjusted as it does not have a visible head on the screw.

Is they're anyone out there that can help?

Sincerely,
 

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70 Deville 77 Fleet 78 Seville 92 Deville 03 Deville
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3,310 Posts
There is a fast idle thingy on the throttle body. I think it's a kinda round black plastic thing and it should be plugged in. I think it just twists out but this is all off of memory 20 years ago. When they used to fail you didn't have a fast idle, just a slow idle. Hopefully yours may just be a vacuum leak somewhere.
 

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Discussion Starter #3
So if I can located the thing that unplugs that you mentioned, and just unplug it, will that help fix the fast idle problem im having?
 

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1998 Cadillac STS
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14 Posts
If you remove the air cleaner and towards the back of the throttle body there is a fast idle valve. It is spring loaded. when it fails it will cause a high idle. Either the micro switch on the side failed or the valve itself failed. You can push straight down on the valve while the engine is running and see if the RPMs drop. There have been post about people shimming the valve to make it work. Also could be the coolant temp sensor at the front right of the intake.
 

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Discussion Starter #5
Are you talking about the throttle linkage itself?

Or does the fast idle have anything to do with the long spring thats hooked into the throttle linkage?

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Okay I kinda get what you're saying now. I will look for a secondary spring hooked to a valve behind the air breather on it tomorrow.

Thanks for your expertise!
 

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1998 Cadillac STS
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No its not on the linkage. It's actually in the throttle body. its toward the rear and has a flat two wire connector that plugs in. It is spring loaded and you can push down on it. unit_1.JPG
 

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Discussion Starter #7
Hello gmaior!!! That name fits you perfect!!! Thanks for the picture also. I did everything you said to the T.

You are right on the money, that piece does control the idle. I unplugged and unscrewed it, however mine is missing the actual spring itself.

I do have another 79 Eldorado which I bought for the motor, but now its shaping up as a parts car.

I am going to remove the part from the parts car and see if the spring is still attached to the part.

So the spring must be a very important component right?
 
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