Idle Problems? Check your Throttle Bodies
Thread Starter
Instructor
Joined: Mar 2009
Posts: 126
Likes: 1
From: Newington CT
Idle Problems? Check your Throttle Bodies
Been fighting an idle problem since day one with an 85' C4.
Finally tracked down the problem.
The throttle shaft bushings are shot on the drivers side of the throttle body, on top of that it looks like the nut that holds the throttle linkage together has been welded on making any kind of repair impossible and not worth it.
How did I find this?
When the car starts the whole linkage shaft would suck itself inward from engine vacuum, then when shut off it would move forward.
Easy to check too with the engine off, it's got at least a 1/4" or better of front to back play in it when you try to move by the lower part of the linkage.
I can't believe it took so long to find the REAL problem.
PS...I have a want ad in the parts section...need to find one by next weekend.
Finally tracked down the problem.
The throttle shaft bushings are shot on the drivers side of the throttle body, on top of that it looks like the nut that holds the throttle linkage together has been welded on making any kind of repair impossible and not worth it.
How did I find this?
When the car starts the whole linkage shaft would suck itself inward from engine vacuum, then when shut off it would move forward.
Easy to check too with the engine off, it's got at least a 1/4" or better of front to back play in it when you try to move by the lower part of the linkage.
I can't believe it took so long to find the REAL problem.
PS...I have a want ad in the parts section...need to find one by next weekend.
Race Director
Joined: Nov 2003
Posts: 12,221
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Yup. Great idea. If upgraded means a bigger one, that's great -- if you're up to 400rwhp or more (or plan on being there soon).
Last edited by GREGGPENN; Jun 23, 2009 at 12:41 AM.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
Good idea buying a new one. You won't inherit someone elses problem. 1/4" is huge. I'm surprised the thing even ran. The motor was probably ready to suck the throttle blades into the motor!
Instructor
Joined: Jun 2008
Posts: 138
Likes: 0
From: Bridgewater Ma.
My 1990 had some driveability issues that were due to a worn TB.
I ended up buying a used BBK on ebay from these guys
http://brothersperformance.com/
I paid $234.00 + shipping. It came in the original box with all necc. gaskets and hardware. It looked as if it had never been used.
The car runs and drives perfectly. The only issue was I could not get the stock air duct to fit the larger TB. I had to use a K&N mounted directly to the TB.
I ended up buying a used BBK on ebay from these guys
http://brothersperformance.com/
I paid $234.00 + shipping. It came in the original box with all necc. gaskets and hardware. It looked as if it had never been used.
The car runs and drives perfectly. The only issue was I could not get the stock air duct to fit the larger TB. I had to use a K&N mounted directly to the TB.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Keeps the plenum alot cooler, I can put my hand on it after running for long periods. Cooler air into motor should make motor run better.Only disadvantage would be if you live where the temperature is below freezing all the time..WW
Last edited by WW7; Jun 23, 2009 at 09:49 AM.
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