Jumping Idle Speed
Thread Starter
Instructor
Joined: Feb 1999
Posts: 139
Likes: 0
From: Peabody, MA
Jumping Idle Speed
My 94 LT1 has just developed an intermittant problem. The engine will be idling normally at 600-700 and all of a sudden it jumps to about 1200 RPM. About a second later, it returns to normal. This can be quite surprising when you're in gear at a set of lights and the car wants to jump ahead. Doesn't happen often, maybe more when the car is cold. Ideas? Thanks in advance any any guidance.
[Modified by Dan94, 4:57 AM 9/9/2003]
[Modified by Dan94, 4:57 AM 9/9/2003]
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Re: Jumping Idle Speed (Dan94)
My first thought is a bad TPS. .....Or worn bushings on the butterfly plate in the throttle body. A problem with either will cause a burst from the injectors as the ECM thinks there is a demand for fuel.
[Modified by ittlfly, 6:16 AM 9/9/2003]
[Modified by ittlfly, 6:16 AM 9/9/2003]
Racer
Joined: Feb 1999
Posts: 394
Likes: 0
From: Amberg, Germany
Re: Jumping Idle Speed (ittlfly)
i have no solution but the same problem. 92 auto. i replaced the iac but nothing. i was thinking about a vaccum leak. or could it be something with the auto trans ?
i hope for some real experts here .
frank :confused:
i hope for some real experts here .
frank :confused:
Safety Car
Joined: Feb 2002
Posts: 4,212
Likes: 10
From: Sun City West Az
Re: Jumping Idle Speed (Frank92)
You also might check you resistance of the injectors. They should be within 1 ohm of each other. It's possible that they could be shorting out. I'd also do a injector balance test. Just a thought.
Safety Car
Joined: May 1999
Posts: 3,651
Likes: 5
From: Atlantis
Cruise-In I Veteran
Re: Jumping Idle Speed (Dan94)
Replace your TPS. About 15 bux.
If still not fixed, remove the IAC and clean it. Don't forget to clean up in there where the pintle fits in the throttle body.
You can replace the IAC for about 60 buks.
That should do it.
If still not fixed, remove the IAC and clean it. Don't forget to clean up in there where the pintle fits in the throttle body.
You can replace the IAC for about 60 buks.
That should do it.
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