SPONSORED LINKS

High idle?

Tiny
BRADLEY WEAVER
  • MEMBER
  • 2002 CHEVROLET S-10
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 250,000 MILES
Idle always stays above 2,500 rpm's.
Thursday, February 13th, 2020 AT 7:33 AM

42 Replies

Tiny
SCGRANTURISMO
  • MECHANIC
  • 4,897 POSTS
Hello,

Usually this is caused by a vacuum leak, and if the RPMs are that high, then a major one. Here is a link to a guide explaining how to track down vacuum leaks. Please pay special attention to the intake manifold portion of the guide.

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

Please go through the guide and get back to us with what you find out.

Thanks,
Alex
2CarPros
SPONSORED LINKS
Was this
answer
helpful?
Yes
No
Thursday, February 13th, 2020 AT 12:24 PM
Tiny
TOUGHDIVER
  • MECHANIC
  • 224 POSTS
Hello,

It could be the throttle valve is not shutting or sticking open, Clean and adjust it and check the throttle cable adjustment. There could also be a massive vacuum leak check the intake gaskets for vacuum leaks. Check the EGR valve for sticking open, Check the brake booster hose and all vacuum lines. Check the Idle Air Control motor pintle for carbon sticking and the throttle valve idle adjustment for tampering. Check the correct positive crankcase ventilation (PCV) valve, properly installed and proper operation of the PCV valve. Check for restricted air intake system. I'm attaching repair guides and component location below. Let us know if you more info.

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

https://www.2carpros.com/articles/idle-air-control-valve-service

Thank you
Loe T.
Images (Click to make bigger)
Thumb
Thumb
Thumb
Was this
answer
helpful?
Yes
No
Thursday, February 13th, 2020 AT 12:55 PM
Tiny
KRISTIN CACY
  • MEMBER
  • 3 POSTS
  • 1995 CHEVROLET S-10
  • 2.2L
  • 4 CYL
  • 2WD
  • MANUAL
  • 240,000 MILES
I just did the heads went to start it and at first backfired and would shut off. Checked the plugs which were new and three of four was fouled out and the fourth one looks untouched. Changed the coil pack and control module now my idle is 3,000 rpm's to 3,300 rpm's.
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:27 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good morning.

Are the plugs fouled with fuel or oil?

The high idle may be from a vacuum leak when you re assembled. Go over your work and make sure all the hoses are connected.

Make sure the throttle body plate is closing at idle as well. If the plate is partially open, it will give you this condition.

Roy

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

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
Was this
answer
helpful?
Yes
No
+1
Wednesday, January 20th, 2021 AT 7:27 PM (Merged)
Tiny
KRISTIN CACY
  • MEMBER
  • 3 POSTS
They are fuel fouled do you by chance a simple vacuum hose diagram?
SPONSORED LINKS
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:27 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Diagram.

Check your injectors to see if they are delivering too much fuel.

Roy
Image (Click to make bigger)
Thumb
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:27 PM (Merged)
Tiny
KRISTIN CACY
  • MEMBER
  • 3 POSTS
How do I check them?
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:27 PM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
You need an injector tester to see the on time commanded by the ECM. You can rent a tester at a parts store to verify.

Roy

https://www.2carpros.com/articles/how-to-test-a-fuel-injector
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:27 PM (Merged)
Tiny
FRED MERTZ
  • MEMBER
  • 2 POSTS
  • 1995 CHEVROLET S-10
  • 4 CYL
  • 2WD
  • MANUAL
I have a 2.2L 4-cyl. Standard, 2 wheel drive. The idle is between 1000-1300 rpms. I have replaced the throttle position sensor and the idle air sensor. Also, the throttle body adjusting screw is backed out as far as it can go. Any ideas on what could be causing the idle to stay up this high(it should be about 750-800 rpm at idle)?
Was this
answer
helpful?
Yes
No
-1
Wednesday, January 20th, 2021 AT 7:28 PM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
These trucks had a problem with the throttle body gasket blowing out. Please remove the unit to inspect.

These guides can help as well

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

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

Please let us know if you need anything else to get the problem fixed.

Was this
answer
helpful?
Yes
No
+3
Wednesday, January 20th, 2021 AT 7:28 PM (Merged)
Tiny
TECUMSEHENGINES
  • MEMBER
  • 2 POSTS
  • 1995 CHEVROLET S-10
  • 2.2L
  • 4 CYL
  • RWD
  • MANUAL
  • 100,800 MILES
Hello. I have a nasty high idle in my 95 chevy s10. I have replaced every single electronic component that would effect the idle. The weird thing is that when I unplug the idle air control valve from the computer, the truck doesn't idle high.

Any help would be appreciated. Thanks
Was this
answer
helpful?
Yes
No
+1
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Try cleaning the IACV out-don't work-look for a vacuum leak-also check the TPS
SPONSORED LINKS
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
TECUMSEHENGINES
  • MEMBER
  • 2 POSTS
I have already done all of that and I still have a intermittent high idle.
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
ODESSA30
  • MEMBER
  • 1 POST
  • 1994 CHEVROLET S-10
  • 4 CYL
  • 2WD
  • MANUAL
  • 203,000 MILES
Just got a 94 chevy s10 it runs great but the idle is to high im not sure what it could be or where to start.
Was this
answer
helpful?
Yes
No
-1
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
First thign to do is check for vaccum leaks.

Check everything after the MAF sensor. If you dont find anything move onto checking for proper function of the pcv valve.
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
LOWX2
  • MEMBER
  • 7 POSTS
  • 1994 CHEVROLET S-10
Engine Performance problem
1994 Chevy S-10 6 cyl Four Wheel Drive Automatic

i did a motor swap on my 94 s10 blazer. After completion, it had a high idle, around 1200 rpms. I drove it till the battery died from trying to start it. When I first put the battery in, it fired right up. As the week past, it wanted to turn the motor less and less, til it died altogether. Recharged the battery, it did the same thing. I am at a loss right now. Anything you could tell me so I can get this truck back in good working order would be greatfully appreciated.
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
LOWX2
  • MEMBER
  • 7 POSTS
Cont>. Also there was a ground wire of some sort that came from the back of the motor and went somewhere. On the donor motor and the original motor, the end that went somewhere were both missing the ring terminal. It was just the wire atteched to the motor.
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Was the donor vehicle the same year--make --model and engine size? Sometimes you have to get the computer from the donor vehicle, if there is any difference. Any applicable mil codes. Can you communicate with the computer. You can check spark at the plugs and fuel pressure, if vehicle is hard to start.

Then, attach the wire to the chassis, if ground.
Was this
answer
helpful?
Yes
No
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
LOWX2
  • MEMBER
  • 7 POSTS
The donor motor was the same block, I think from a 92. All the plugs went to the same place, except on top of the a. C, which I removed altogether. As far as computer from the donor blazer, the truck was smashed after the motor was pulled.
Was this
answer
helpful?
Yes
No
+1
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
You should be able to check mil codes? You use a jumper wire between the A & B terminals at the datalink connector, turn the key just till the dash lites come on, no further. The mil starts flashing, you count the flashes to get the codes. If no communication with computer, not sure what to tell you?
Was this
answer
helpful?
Yes
No
-1
Wednesday, January 20th, 2021 AT 7:29 PM (Merged)

Please login or register to post a reply.

Related Engine Idle High Content

VIEW MORE

Sponsored links