90 Idles High---Still
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Instructor
Joined: Dec 2007
Posts: 111
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From: Muscatine Iowa
90 Idles High---Still
When the car is running, the vacuum will hold it open and it will idle around 1500. If the car is not running, it returns fine. Engine vacuum, not a worn throttle blade, will hold it open. It is a new throttle body. I put springs on it that will help to overcome the problem but then you need a lead shoe to depress the accelerator pedal.
--I recently changed the motor, same problem
--I have unhooked the cables, same problem
--I have changed the coolant temp sensor, same problem
--I replaced the IAC, same problem
--I have replaced the throttle body, same problem
--I have replaced the TPS, same problem
Yesterday, I replaced the MAP sensor, unhooked the IAC and the TPS, turned the key to the "on" position for 3 minutes. Turned the key "off". Hooked the TPS and IAC back up. Started the car and it idled perfectly, drove it about 10 miles, perfect, idled down, perfect. I stopped and shut the car off, unhooked the one TB helper spring, (I was feeling good about it now) drove it a few more miles, perfect. Drove it another ten miles, IDLES HIGH UNTIL YOU KICK IT ONCE.. IT"S BACK...............
--I recently changed the motor, same problem
--I have unhooked the cables, same problem
--I have changed the coolant temp sensor, same problem
--I replaced the IAC, same problem
--I have replaced the throttle body, same problem
--I have replaced the TPS, same problem
Yesterday, I replaced the MAP sensor, unhooked the IAC and the TPS, turned the key to the "on" position for 3 minutes. Turned the key "off". Hooked the TPS and IAC back up. Started the car and it idled perfectly, drove it about 10 miles, perfect, idled down, perfect. I stopped and shut the car off, unhooked the one TB helper spring, (I was feeling good about it now) drove it a few more miles, perfect. Drove it another ten miles, IDLES HIGH UNTIL YOU KICK IT ONCE.. IT"S BACK...............
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Team Owner
Joined: Jul 2004
Posts: 28,474
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From: Hartford WI
Do you have a scanner? I would set it off the IAC counts. Screw it in if the counts are high and screw it out if the counts are low. Aim for 15-20 counts. After that, set TPS if it is adjustable. Before all this is done, timing must be spot on.
Thread Starter
Instructor
Joined: Dec 2007
Posts: 111
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From: Muscatine Iowa
The TPS is non-adjustable. I have not been able to try setting the IAC with a voltmeter. I have had it to several shops, thrown $100 bills at it and am trying to figure this out on my own now.
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Thread Starter
Instructor
Joined: Dec 2007
Posts: 111
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From: Muscatine Iowa
This is a throttle body from xtreme-fi. My concern is that it even has the right IAC valve. There is a difference between one for an 88 and one for a 90 even though the look the same. Without ordering another new one, I do not remember which valve is in the car. They look the same.....
Last edited by Tripleblack90; Sep 2, 2009 at 03:56 PM.
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
Thread Starter
Instructor
Joined: Dec 2007
Posts: 111
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From: Muscatine Iowa
Replaced the ECM. Reset the base idle. Took it for a 1/2 hour drive. Life seems goods again..............This has been very frustrating.
As I side note, while resetting the base idle, trying to unhook the EST wire, I think I un-hooked the right one. The tach does not work when it is unhooked. Oh well, the car is running good again. It is hard to drive keeping your fingers crossed.
As I side note, while resetting the base idle, trying to unhook the EST wire, I think I un-hooked the right one. The tach does not work when it is unhooked. Oh well, the car is running good again. It is hard to drive keeping your fingers crossed.
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
Replaced the ECM. Reset the base idle. Took it for a 1/2 hour drive. Life seems goods again..............This has been very frustrating.
As I side note, while resetting the base idle, trying to unhook the EST wire, I think I un-hooked the right one. The tach does not work when it is unhooked. Oh well, the car is running good again. It is hard to drive keeping your fingers crossed.
As I side note, while resetting the base idle, trying to unhook the EST wire, I think I un-hooked the right one. The tach does not work when it is unhooked. Oh well, the car is running good again. It is hard to drive keeping your fingers crossed.
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
Thread Starter
Instructor
Joined: Dec 2007
Posts: 111
Likes: 0
From: Muscatine Iowa
I used to work on my stuff all of the time. Got to that point in my life that I would prefer to pay someone to work on it for me. Unfortunately, competent mechanics that are familiar with older vettes are few and far between. I decided to get my hands dirty and fix it myself.......now I know why I prefer to have someone else work on stuff.......
