1991 L98 Engine Racing
Thread Starter
7th Gear
Joined: Sep 2012
Posts: 7
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1991 L98 Engine Racing
I have experienced engine racing at times when idling at a stop. It's a little scary but braking fast and going to neutral and tapping the gas pedal brings it back to a normal idle. This happens occasionally and I am concerned when other people have to drive this car. I would appreciate any thoughts on correcting this problem.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
Typical of a worn out throttle body.
The holes the butterfly shafts run in get elongated and when the throttle is released the butterflies are pulled to one side jamming up on the bore
until your tap knocks them free to the idle position
Also check for free movement of the throttle cable ; may be frayed and causing sticking
The holes the butterfly shafts run in get elongated and when the throttle is released the butterflies are pulled to one side jamming up on the bore
until your tap knocks them free to the idle position
Also check for free movement of the throttle cable ; may be frayed and causing sticking
Max G’s
Joined: Nov 2008
Posts: 2,751
Likes: 78
From: Monroe OH
NCM Sinkhole Donor
Typical of a worn out throttle body.
The holes the butterfly shafts run in get elongated and when the throttle is released the butterflies are pulled to one side jamming up on the bore
until your tap knocks them free to the idle position
Also check for free movement of the throttle cable ; may be frayed and causing sticking
The holes the butterfly shafts run in get elongated and when the throttle is released the butterflies are pulled to one side jamming up on the bore
until your tap knocks them free to the idle position
Also check for free movement of the throttle cable ; may be frayed and causing sticking
Thread Starter
7th Gear
Joined: Sep 2012
Posts: 7
Likes: 0
Further Question
As I think about what is occurring I don't understand what can force acceleration when the car is stopped for awhile at a stop light while ideling nicely and all of a sudden the engine races severely on its own without me touching the gas pedal. Can someone explain this and what I can do to correct. Thank you.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
"braking fast and going to neutral and tapping the gas pedal brings it back to a normal idle". ;
not that the revs would randomly raise from normal idle speed after you were stopped.
Different problem to the TB I mentioned
Your IAC ( controlled by the computer ) as mentioned above is not controlling the idle speed correctly.
Start by removing and cleaning it
Thread Starter
7th Gear
Joined: Sep 2012
Posts: 7
Likes: 0
More Info & Another Question
Vetteoz thank you for your response and sorry about not being more clear.
I also want to add that this problem has continued on an intermittent basis for at least 10 years. By intermittent I mean once every 4 to 6 weeks. I drive it only in the summer months and put on about 500 miles per month.Years ago I was told it was the fuel injectors and had those replaced and it had no effect. Also I have put Sea Foam in the gas numerous times and the idle is generally 1000 rpm. I will definitely take your advice this week.
My additional question is that since this problem is so intermittent I wonder if the problem might be in the computer. Might the PCV valve or a sensor cause this? I want to do the easiest and less costly possible solutions first. Are there any other actions you would take at this time in addition to cleaning the AIC. And is there any way to tell if the problem is fixed in stead of waiting for it to happen again?
Thanks again for your response.
I also want to add that this problem has continued on an intermittent basis for at least 10 years. By intermittent I mean once every 4 to 6 weeks. I drive it only in the summer months and put on about 500 miles per month.Years ago I was told it was the fuel injectors and had those replaced and it had no effect. Also I have put Sea Foam in the gas numerous times and the idle is generally 1000 rpm. I will definitely take your advice this week.
My additional question is that since this problem is so intermittent I wonder if the problem might be in the computer. Might the PCV valve or a sensor cause this? I want to do the easiest and less costly possible solutions first. Are there any other actions you would take at this time in addition to cleaning the AIC. And is there any way to tell if the problem is fixed in stead of waiting for it to happen again?
Thanks again for your response.
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