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Engine has high idle?

Tiny
BRADVL
  • MEMBER
  • 1990 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 76,000 MILES
My truck will start and run until it heats up and then it will idle up some and runs kinda rough? Usually will die and then will not restart until cool. I have already gave basic tuneup like plugs, wires, rotor cap and rotor, coil and egr valve? Please help
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Monday, September 27th, 2010 AT 11:07 AM

10 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Have you checked the fuel pump pressure? Has the check engine light come on?

This guide will help

https://www.2carpros.com/articles/engine-idles-too-high

Please run down this guide and report back.
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Monday, September 27th, 2010 AT 1:40 PM
Tiny
BRADVL
  • MEMBER
  • 2 POSTS
Yes check engine light is on
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Monday, September 27th, 2010 AT 1:58 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
If the check engine light is on, there is a trouble code stored in the computer. What you need to do is have the computer scanned to identify the code. The code will then identify where the problem is coming from. Most parts stores will scan it for free. Do that and let me know what you find.

Joe
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Tuesday, September 28th, 2010 AT 7:10 AM
Tiny
LEMAGOO
  • MEMBER
  • 2 POSTS
  • 1989 CHEVROLET SILVERADO
  • V8
  • RWD
  • AUTOMATIC
  • 122,000 MILES
When I start my truck it idles very high then after about 20 seconds the idle lowers just a little but the idle stays very high. It also smells like it is running rich. Can you please tell me how to fix this problem.
Thanks Lou
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Thursday, June 18th, 2020 AT 1:22 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Check for a vacuum leak around the tbi unit base, they like to blow the gasket there it's pretty common, just use choke cleaner rpm will change if it's there. Also check hoses for soft/cracked off
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Thursday, June 18th, 2020 AT 1:22 PM (Merged)
Tiny
67 CHEVY
  • MEMBER
  • 1 POST
  • 1988 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 200,000 MILES
Engine starts and runs fine then the high idle comes off and usually stalls. If it stays running it allways stalls when you put it in gear.
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Thursday, June 18th, 2020 AT 1:22 PM (Merged)
Tiny
KARATTOP
  • MEMBER
  • 5 POSTS
Did you check your fuel pump? It could be that it is weak - I've heard that sometimes a car can run with no fuel pump at all because the vacuum in the engine is enough to suck the fuel from the tank, but under low idle the vacuum goes down and maybe it can't pull the fuel any longer.

How sure are you of the link between the idle and the stall? Could it be that a certain temp is reached? Check your CTS or other sensors that are temp dependent (IAT for example). Also, something such as a crank position sensor can go wacko when they get warm. I'm not sure if your truck has a CPS, but think along those lines.
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Thursday, June 18th, 2020 AT 1:22 PM (Merged)
Tiny
JDS327
  • MEMBER
  • 2 POSTS
  • 1986 CHEVROLET SILVERADO
1986 Chevy Silverado V8 Two Wheel Drive Automatic

When I crank the truck it idles high and when I shift to drive it will get up to 25mph without me giving it gas. Then if turned off before it gets warmed up good it knocks and sputter before it cuts off. I'm using mid-grade fuel now, but what can be done to fix this?
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Thursday, June 18th, 2020 AT 1:22 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Choke stuck either vacuum break or linkage needs cleaning. 5.0l or 5.7L?
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Thursday, June 18th, 2020 AT 1:22 PM (Merged)
Tiny
JDS327
  • MEMBER
  • 2 POSTS
5.7
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Thursday, June 18th, 2020 AT 1:22 PM (Merged)

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