High Idle

Tiny
RYAN SOUTH
  • MEMBER
  • 2003 JEEP LIBERTY
  • 110,000 MILES
Hello, My name is Ryan. I have a question about a Jeep Liberty. 3.7L 6 cyc. Auto with AC.
The Jeep was driving when the RPM started going extremely high. The Jeep has a new battery (6 months ago), Automatic trans. The problem happens all the time now. It happens with the AC or without. Previously there was a problem with the Jeep stalling. The RPM would go very low then stall. I had the stalling problem addressed: a mechanic cleaned the sensor for idling speed and that helped the low RPM for awhile. It worked recently and stoped the stalling but it did stall again recently (only a few times in the last few months not like before the cleaning) I wanted them to change the sensor but they did not have one (I brought the car to Mexico for my vacation place). Sometimes this prohibited me from using the AC. Now the problem is the opposite-the RPM goes really high. It started on the highway but now does it in traffic as well. The car is in Mexico. It is VERY humid here. Sea level altitude. The check engine light has always been on on this vehicle for the last few years along with other lights on the dash (ABS light, brake light, engine light). The jeep recently had an AC swtich be replaced. Seems like the truck always has electrical problems. The transmission seems to not be shifting correctly during the problem. Gas here is very dirty, I had run the tank to very low (supposed to fill on 1/4 tank to avoid the dirt from the bottom of the tank is suggested here). I am not sure if that could be part cause. The truck is pretty much undrivable right now. The mechanics here are not very good. They are especially poor at diagnosis. I would appreciate any help you can shed on this matter! Thank you.
Sunday, March 17th, 2013 AT 4:49 PM

11 Replies

Tiny
CJ MEDEVAC
  • MECHANIC
  • 11,004 POSTS
This will cost you less than $10 to try

here, is what controls idle (idle air control)....it has a plunger in it that constantly moves, allowing itsy-bitsy amounts of air to bypass the closed throttle valve to mix with the fuel from the injectors

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_idle-air-control-valve-bwd_20474590-p?searchterm=iac+valve

i'm pasting in my experience with the wifey's '03 ford escape....robbed it from another answer i gave......back when i used lower case lettering!.......this saves me from a bunch of hunting and pecking.

our escape would idle low, then it got to point it would die when you stopped.

revving + holding brake was only way to keep it running. i took it to fellow r/c airplane pilot, he doubles as a s.c. state hwy dept mechanic.

when i got to his house, he was repairing a tractor. i told him my sob story. the escape was still barely running, i raised the hood.

he said, (and i quote).............."it could be the idle air control (iac)", as he pointed to it, and emphasized it with a sharp rap, using the wrench in his hand.

it straightened right up, and ran damn good!!!

..............that was a 15/16 craftsman wrench, box end, kinda a medium rap!!!

yes, i visited parts store and replaced it..............hope this helps

we took the iac off and cleaned it, it seemed fine, but just because the engine had over 100,000 miles on it, i went ahead and replaced it (preventative maintenance). i figgered it had been moving and wearing for a long time

this is the wife's rig, so that was the big factor!----i take no chances---she'll whoop my butt!

this is a very simple thing to clean or replace.......no need to take it to the stealership!i "might" even be able to show you how to save a bundle, should you decide to replace it

the only difficult thing about it is not to drop the 2 screws you removed to take it off!!!

we're gonna use "throttle body cleaner and clean the iac and the hole it came out of

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_throttle-body-and-air-intake-cleaner-crc_7040065-p?searchterm=throttle+body+cleaner

here's some more info on saving $$$........a similar method may work at other stores too

https://www.2carpros.com/questions/2001-dodge-neon-milage-just-want-put-fliuds-their-locations

one of these would greatly aid you in the future

https://www.2carpros.com/questions/2007-ford-taurus-tune-up

keep us posted as you progress

the medic

these pics are of the wife's ford escape and of my "real vehicles"......yours iac is sorta similar in location
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Sunday, March 17th, 2013 AT 5:27 PM
Tiny
BUDS56
  • MEMBER
  • 3 POSTS
  • 2004 JEEP LIBERTY
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 55,000 MILES
My jeep liberty engine will rev up all by its self. Sometimes going down the street but seems like that it does'nt engage transminsion
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Friday, September 21st, 2018 AT 10:11 AM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Is it like the trans goes into neutral and engine goes up?
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Friday, September 21st, 2018 AT 10:11 AM (Merged)
Tiny
BUDS56
  • MEMBER
  • 3 POSTS
Yes, also when you are sitting in park
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-1
Friday, September 21st, 2018 AT 10:11 AM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Maybe a fault in Idle Air Control Motor which controls engine RPM via the PCM. Has the check engine light come on? Need to have a scanner hooked up to check out operation of IAC/TPS
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Friday, September 21st, 2018 AT 10:11 AM (Merged)
Tiny
BUDS56
  • MEMBER
  • 3 POSTS
Yes the engine light comes on and stays on for awhile. Would you recommend just changing the motor or go ahead and have it scanned? Had a friend with a car hand held diagnostic scanner and he said that it showed a accelerator switch? Thank you for your help.
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Friday, September 21st, 2018 AT 10:11 AM (Merged)
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Did you get a code for TPS? What was code in P0xxx format
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Friday, September 21st, 2018 AT 10:11 AM (Merged)
Tiny
2CP-ARCHIVES
  • MEMBER
  • 4,540 POSTS
  • 2004 JEEP LIBERTY
  • 65,000 MILES
Why does the engine rev up slightly when I engage the brakes. This doesn't happen all the time just occasionally.
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Friday, September 21st, 2018 AT 10:12 AM (Merged)
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Check for any vacuum leaks.

Roy
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Friday, September 21st, 2018 AT 10:12 AM (Merged)
Tiny
IBGONZALES
  • MEMBER
  • 1 POST
  • 2002 JEEP LIBERTY
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 161,600 MILES
Idle does not work during start up. It takes almost ten minutes till the engine warms up then engine idle works.
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Friday, September 21st, 2018 AT 10:12 AM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,758 POSTS
You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.
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Friday, September 21st, 2018 AT 10:12 AM (Merged)

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