Idling Problem
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Joined: Oct 2014
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Idling Problem
Hi, I replaced both IAC controls on my 84 Corvette it has a 350 crossfire it was idling bad so I replaced them... I was surprised when I started it up ran smooth so I took it down the road when I got back the temp was 205 and the idle was at 1500 rpm a little high it never came down to 8/900 rpm what went wrong.. any help... Thanks for your time
Zen Vet Master Level VII
Joined: Mar 2016
Posts: 5,218
Likes: 1,174
From: Southlake, TX
My guess would be that you still have vacuum leaks. Try tightening all the manifold bolts, TB mounts and check all your rubber hoses, trimming a 1/4 inch off if you find cracks on the ends.
Last edited by billschroeder5842; Aug 3, 2017 at 12:02 PM.
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Joined: Oct 2014
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Thanks I'll check them manifold bolts.. all vacuum hose's look good Thanks for your time..
Safety Car
Joined: May 2001
Posts: 4,757
Likes: 1,647
From: Fairfax Virginia
Potentially 33 year old rubber lines....
Hello there,
I agree with the previous post but I want to emphasize that the vacuum leaks from old hoses will drive you crazy. When I had a vacuum leak I went around and did a visual inspection. The lines "looked new" but that was because somebody put silicone or whatever on them.
My lines were crumbling in places out of reach or sight, everywhere else they looked great. After replacing one of the lines connected to the Cruise Controls all of my vacuum issues went away. It turned out that it was leaking right where it connected.
Eliminate the most likely place for a vacuum leak to occur. The hoses are far more likely than the manifold bolts.
Good Luck getting that Vacuum system under control!
I agree with the previous post but I want to emphasize that the vacuum leaks from old hoses will drive you crazy. When I had a vacuum leak I went around and did a visual inspection. The lines "looked new" but that was because somebody put silicone or whatever on them.
My lines were crumbling in places out of reach or sight, everywhere else they looked great. After replacing one of the lines connected to the Cruise Controls all of my vacuum issues went away. It turned out that it was leaking right where it connected.
Eliminate the most likely place for a vacuum leak to occur. The hoses are far more likely than the manifold bolts.
Good Luck getting that Vacuum system under control!
Thread Starter
Advanced
Joined: Oct 2014
Posts: 81
Likes: 0
Hello there,
I agree with the previous post but I want to emphasize that the vacuum leaks from old hoses will drive you crazy. When I had a vacuum leak I went around and did a visual inspection. The lines "looked new" but that was because somebody put silicone or whatever on them.
My lines were crumbling in places out of reach or sight, everywhere else they looked great. After replacing one of the lines connected to the Cruise Controls all of my vacuum issues went away. It turned out that it was leaking right where it connected.
Eliminate the most likely place for a vacuum leak to occur. The hoses are far more likely than the manifold bolts.
Good Luck getting that Vacuum system under control!
I agree with the previous post but I want to emphasize that the vacuum leaks from old hoses will drive you crazy. When I had a vacuum leak I went around and did a visual inspection. The lines "looked new" but that was because somebody put silicone or whatever on them.
My lines were crumbling in places out of reach or sight, everywhere else they looked great. After replacing one of the lines connected to the Cruise Controls all of my vacuum issues went away. It turned out that it was leaking right where it connected.
Eliminate the most likely place for a vacuum leak to occur. The hoses are far more likely than the manifold bolts.
Good Luck getting that Vacuum system under control!
Melting Slicks
Joined: Jan 2008
Posts: 2,054
Likes: 120
From: AZ
The throttle bodies are know to wear/enlarge due to butterfly shaft movement. Decades ago, I got a kit with bushings and a drill bit to repair. That air has most impact at idle, but many other possibilites should be eliminated before doing this.
A vacuum gauge can be your best friend.
A vacuum gauge can be your best friend.
