My truck is idling really high?

2000 CHEVROLET S-10
225,114 MILES • 4 CYL • 2WD • MANUAL
Avatar
BRIANNA ALETA
  • MEMBER
  • 4 POSTS
When I crank it up it idles very high. It will go down a little bit when I first crank it up but when I'm driving it and go to stop and mash the clutch it idles very high again. I know I have a vacuum leak somewhere in the HVAC system when I cut the defrost or feet on you can hear the difference. I also have a black vacuum hose coming off the top of the engine that I have no clue where it goes.
Apr 16, 2023 at 10:09 AM
Advertisement
Avatar
STRAILER
  • ✓Experienced Mechanic
  • 55,065 POSTS
This sounds like you may have a vacuum leak under the throttle body, or the IAC motor needs to be replaced and the passages serviced (cleaned).

Here is a guide that can help:

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

And use this guide when the engine is cold only:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Here is the location of the IAC motor so you can swap it out. Check out the images (below). Please let us know what happens.
Image (Click to enlarge)
Professional Diagram for 2CarPros Members
Click here to log in and view diagram.
Apr 17, 2023 at 5:10 AM
Join 2CarPros for free, one of the most advanced car repair communities on the internet. From first-time drivers to seasoned mechanics, everyone is welcome to reply, share details, and get better answers. You can add a temporary image or video first; uploads are limited to 20 MB.
Ask a Free Question
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.