Low idle problems

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Feb 11, 2013 | 10:30 PM

#76

70hemicuda

Senior Member

Joined: Feb 2012

Posts: 627

Likes: 3

From: newjersey

Year: 2000

Model: Cherokee

Engine: I6

Right now it idles 500rpm and rough with no defrost and about 650 and better with defrost. Could my iac be bad?

Feb 11, 2013 | 11:28 PM

#77

salad

Herp Derp Jerp

Joined: Nov 2011

Posts: 18,251

Likes: 17

From: Parham, ON

Year: 1999

Model: Cherokee

Engine: 4.0L OBD-II

Quote:

Originally Posted by 70hemicuda

So when i have my defroster on, my idle noticeably improves. Less rough and doesnt miss alot. Any reason to why this is?

Quote:

Originally Posted by cruiser54

All I can think of is the aC compressor kicks on with defrost and the eCU sends a signal to the IAC to move and increase the idle speed.

Is this only on defroster mode? A vacuum leak may provide the engine with extra air.

EDIT: Why don't you try yanking the A/C compressor relay from the PDC and see if it does or doesn't change?

Last edited by salad; Feb 11, 2013 at 11:42 PM.

Feb 12, 2013 | 06:15 AM

#78

70hemicuda

Senior Member

Joined: Feb 2012

Posts: 627

Likes: 3

From: newjersey

Year: 2000

Model: Cherokee

Engine: I6

Its when the compressor is on. And i can try that.

Feb 15, 2013 | 09:58 PM

#79

70hemicuda

Senior Member

Joined: Feb 2012

Posts: 627

Likes: 3

From: newjersey

Year: 2000

Model: Cherokee

Engine: I6

well i tried what was suggested and no change. After some hardcore reading around i found out it could be my TPS. symptoms are rough idle, slight miss, RPMs drop from 1000 at start up to 500 warm, bucking at stops. Could this be the TPS? im gonna check voltage readings tomorrow but just want some input. this thing is driving me crazy.

Feb 16, 2013 | 08:01 AM

#80

modelcar

Junior Member

Joined: Jan 2013

Posts: 78

Likes: 0

From: California

Year: 2001

Model: Cherokee

Engine: 4.0

Do you have shift point problems? When my TPS went out my shift points were off, by a noticeable amount.

Feb 16, 2013 | 08:14 AM

#81

70hemicuda

Senior Member

Joined: Feb 2012

Posts: 627

Likes: 3

From: newjersey

Year: 2000

Model: Cherokee

Engine: I6

Some days it shifts really good, others it jerks a noticeable amount

Feb 16, 2013 | 08:51 AM

#82

cruiser54

::CF Moderator::

Joined: Aug 2011

Posts: 43,971

Likes: 1,579

From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by 70hemicuda

Some days it shifts really good, others it jerks a noticeable amount

Replace your TPS and do this while you're at it.

https://www.cherokeeforum.com/f2/free-quick-fix-41821/

Feb 16, 2013 | 08:58 AM

#83

70hemicuda

Senior Member

Joined: Feb 2012

Posts: 627

Likes: 3

From: newjersey

Year: 2000

Model: Cherokee

Engine: I6

Ive done that a bunch of times thinking that was my problem. Guess i know why it never fully worked now lol

Feb 16, 2013 | 08:59 AM

#84

cruiser54

::CF Moderator::

Joined: Aug 2011

Posts: 43,971

Likes: 1,579

From: Prescott, Az

Year: 1990

Model: Cherokee (XJ)

Engine: 4.0

Quote:

Originally Posted by 70hemicuda

Ive done that a bunch of times thinking that was my problem. Guess i know why it never fully worked now lol

Oh, the TV cable adjustment or replace the tPS?

Feb 16, 2013 | 09:06 AM

#85

70hemicuda

Senior Member

Joined: Feb 2012

Posts: 627

Likes: 3

From: newjersey

Year: 2000

Model: Cherokee

Engine: I6

The cable adjustment. My bad for not specifying. As far as i know the tps is stock, so i will be replacing that soon. Hopefully thats my problem

Feb 28, 2013 | 11:50 AM

#86

Mlcantin

Thread Starter

Junior Member

Joined: Apr 2012

Posts: 84

Likes: 0

From: Memphis, Tennessee

Year: 2000

Model: Cherokee

Engine: 4.0 Liter, Inline 6

Nothing wrong with idle. Tach is just off due to pc being faulty. Idles perfect. The whine i had was a loose hose to the right of the air filter. Perfect jeep