idle issue .. at cold start up .. any advice - thanx in advance - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Grand Cherokee & Commander Forums > ZJ Grand Cherokee Forum > idle issue .. at cold start up .. any advice - thanx in advance

Safety Thimble FairleadsEngo winches available at www.rockridge4wd.com! Free shippBLACK FRIDAY SPECIALS!! You asked, we deliver!

Reply
Unread 07-26-2006, 03:01 PM   #1
sanboy
Registered User
 
Join Date: Jan 2006
Posts: 288
idle issue .. at cold start up .. any advice - thanx in advance

never happened before ...

drove about 1800 miles on a trip ... got here no problems ..

now every once and while in the morning .. ONLY morning start up
( SEEMS TO HAPPEN 1 TIME IN EVERY 7 DAYS OR SO )

the vehicle will surge all the way to 2000 rpm . then back to 1000 then up to 2000 rpm . then finnally settle in at around 700 or so .....

onec the vehicle is started and it settles down and is driven never happens again that day ..

WHAT SHOULD I BE LOOKING FOR .. ?

any ideas ... ?

thanx in advance for the help

__________________
2001 JEEP Grand Cherokee Limited
4.7 - 4x4
sanboy is offline   Reply With Quote Quick reply to this message
Unread 07-26-2006, 03:37 PM   #2
greasefingers
Registered User
1994 ZJ 
 
Join Date: Sep 2003
Location: Northern VA, USA, NJ
Posts: 8,237
In the Throttle body the butterfly is completely closed at idle. Above and below the butterfly is a channel or bypass. This bypass is the only way for air to enter the manifold, during idle. The butterfly or throttle plate only opens when you touch the gas pedal. In this channel/bypass is a plunger for controlling the airflow rate. A motor moves the plunger in & out. This plunger/motor combo is the Idle Air Control Motor (IAC). Air for start-up and idling is controlled by the PCM. It tells the IAC how much to open/close to let air into the intake manifold.

Symptoms of a bad IAC: hunting behavior of the rpms, extremely high or low idle speeds.

Therefore your problem is most likely one of two things: a dirty or frigged IAC or a faulty TPS throttle position sensor. I would suggest spraying the hell out of the throttle body with electrical cleaner and spray up into the IAC passage.
__________________
Cheers Steve

94 Black Laredo 4-Liter with QuadraTrac (42RE trans & NP249 TC) 200,000 + miles purchased new

88 Cherokee 2-door with 5speed manual 139K miles(deceased) purchased new

Last edited by greasefingers; 07-26-2006 at 09:03 PM..
greasefingers is offline   Reply With Quote Quick reply to this message
Unread 07-26-2006, 08:52 PM   #3
sanboy
Registered User
 
Join Date: Jan 2006
Posts: 288
thanx .. will look into that first thing tommorrow morning
__________________
2001 JEEP Grand Cherokee Limited
4.7 - 4x4
sanboy is offline   Reply With Quote Quick reply to this message
Unread 07-26-2006, 10:18 PM   #4
zaq123
Registered User
1941 JK Wrangler 
 
Join Date: Jul 2004
Location: here
Posts: 3,999
Quote:
Originally Posted by greasefingers

Therefore your problem is most likely one of two things: a dirty or frigged IAC or a faulty TPS throttle position sensor. I would suggest spraying the hell out of the throttle body with electrical cleaner and spray up into the IAC passage.

99% IAC. My WJ had that problem. Take it out of TB and you'll see how much carbon got stuck to IAC valve.
zaq123 is offline   Reply With Quote Quick reply to this message
Unread 08-11-2006, 01:33 AM   #5
sanboy
Registered User
 
Join Date: Jan 2006
Posts: 288
spraying it down with MOPAR COMBUSTION CHAMBER spray would work ?
__________________
2001 JEEP Grand Cherokee Limited
4.7 - 4x4
sanboy is offline   Reply With Quote Quick reply to this message
Unread 08-13-2006, 05:57 PM   #6
mtcox
Registered User
2001 WJ 
 
Join Date: May 2006
Posts: 115
I went through this same thing with my 2001 Grand Cherokee. Cleaned the throttle body, didn't work. It was the TPS. I replaced it but apparently I didn't position it properly when I put it back in. The result was erratic shifting, no cruise control and a check engine light. It's a $30 part and solved the problem but be sure it's positioned correctly.
mtcox is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.