Engine Low Idle?

Tiny
AKUBRICH
  • MEMBER
  • 2000 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 170,000 MILES
My 2000 Cherokee idles ok when shifted into park and then gradually lowers until it stalls. It starts back up ok but the problem repeats. It is not intermittent
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Thursday, April 2nd, 2009 AT 7:46 AM

21 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,005 POSTS
Chances are it is an idle air control valve (IAC) or the throttle position sensor (TPS). However, without a code from the computer to identify it, it's only a guess. Has the check engine light ever come on?

This guide can help us fix it

https://www.2carpros.com/articles/stall-at-idle

Please run down this guide and report back. Joe
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Tuesday, April 7th, 2009 AT 8:33 PM
Tiny
RYANFLC
  • MEMBER
  • 2 POSTS
  • 1997 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • MANUAL
  • 133 MILES
I have a 1987 Jeep Cherokee 4.0L with 130k miles.

It has an odd idle issue that I will do my best to describe. Note that I have checked the distributor cap, cleaned the throttle body and I think I have checked the vacuum system pretty thoroughly, but I am not an expert in cars by any means.

First of all, for the first 5 minutes or so of driving, the idle drops really low when put into N, to under 200 RPM. It instantly recovers and then runs at about 700 or 800 RPM. After 5 minutes of driving, it stops doing this. This happens every time I drive it.

Secondly, When accelerating, once in a while the RPMs instantly drop for a split second. This creates a strong****** motion in the jeep. It seems to be most likely to happen when the road is bumpy but that could just be a coincidence.

After that happens, the Jeep runs fine except if I put it into N, sometimes it will die instantly for a minute. Sometimes it is also hard to start the jeep back up if it dies this way too. It seems like I have to wait a minute or two before it will start.

Sometimes, after this type of issue, the RPMs will run very high for a few minutes when in N, somewhere around 1500 RPMs. After a few minutes, the RPMs return to normal

The problem is very occasional. Sometimes I can drive all day without it happening once and other times it happens every 5 minutes.

Thanks for reading, any thoughts?
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Monday, January 11th, 2021 AT 10:49 AM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Any applicable mil codes? You can check those codes yourself. Turn the key just till the dash lites come on, no further. cycle the key on--off, on--off, on, then the mil starts flashing, you count the flashes to get the codes. Your looking for two digit codes. Anything?

This guide can help

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

How long since overall tune-up? Use a gage and check fuel pressure. With intermittent issues, I have to test when problem is ongoing. I would also want to look at sensor signals.
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Monday, January 11th, 2021 AT 10:49 AM (Merged)
Tiny
RYANFLC
  • MEMBER
  • 2 POSTS
Thanks alot, I'll give those ideas a try.
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Monday, January 11th, 2021 AT 10:49 AM (Merged)
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
Let us know what you find.
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Monday, January 11th, 2021 AT 10:49 AM (Merged)
Tiny
IAMZ400RIDER
  • MEMBER
  • 1 POST
  • 1997 JEEP CHEROKEE
  • V8
  • AWD
  • AUTOMATIC
  • 150,000 MILES
I have a 1997 jeep grand cherokee 5.2 v8. It idles low about 500rpms and sometimes it will stall when you come to a stop but will always start back. Also if I fill up completely with gas it will smell of gas and leak out some on the ground. The smell and leaking is not present from 3/4 tank to empty. Any ideas would help me alot thanks.
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Monday, January 11th, 2021 AT 10:49 AM (Merged)
Tiny
SERVICE WRITER
  • MECHANIC
  • 9,123 POSTS
MAy be good to check if any codes are present.

The fuel leak may or may not be related. Regardless the fuel pressure needs to be checked when the problem is happening to determine if the is fuel related.
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Monday, January 11th, 2021 AT 10:49 AM (Merged)
Tiny
B55DEPP
  • MEMBER
  • 1 POST
  • 1996 JEEP CHEROKEE
  • 22,500 MILES
I have a really crazy problem with my 96 cherokee automatic idling low. I have changed the air idle control, TPS, Both oxy sensors, new battery, Plugs, wires, cap rotor, new battery/gnd cables, new cat & exhaust, cleaned and checked throttle body, no vaccum leaks ican detect, charging good. I do have a crack inthe exhaust manifold dealer tells me but not bad. Checked map sensor ok I think but did not change. Jeep will start up and idle fine (750)when cold but after driving for 10-20 minutes the idle drops to 250-200 at stoplights. Or under and sometimes stalls at stoplights. When stalls Starts right back up. Weird thing to me and very telling is if I disconnect neg cable for a few minutes. Jeep will idle fine for a day but next day low idle problem will return. Jeep runs great and good power & oil pressure. I am at my wits end and this is my wifes daily driver and shes gonna get rearended I gotta get this fixed. I am pretty good backyard mechanic but this one is tough. Anybody got any ideas or experiences? Any help much appreciated
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
BILLYMAC
  • MECHANIC
  • 2,204 POSTS
You can also manually trigger a relearning procedure. If you disconnect the cables leading to your vehicle's battery, the computer's source of power, and leave them disconnected for at least half an hour, you have essentially turned off your vehicle's computer and forced it to reboot. After the computer reboots, it will relearn your vehicle's system parameters by running a new diagnostic check as you drive.

Perhaps the easiest relearning procedure is automatic relearn. This takes place when the computer has been programmed to recognize that maintenance has been done on the vehicle, such as tire rotation. The computer then readjusts everything on its own without needing to be told what was done. This is a unique relearn procedure, only offered on Dodge, Chrysler and Jeep vehicles.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
TROOPER 1
  • MEMBER
  • 6 POSTS
  • 1996 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 204,000 MILES
I have an occasional problem where my Cherokee sometimes dies at idle or almost dies. Every now and then it bogs going down the road. I am almost lost here and I am not a car idiot. I have replaced a distributor, fuel pump, fuel filter and coil very recently. Within the last couple years I have replaced the map, Iac, Tbs, brain box, crank sensor, ignition switch, and just about everything else electrical as well. The problem happens at no specific time. At idle long enough it starts to miss and sometimes dies. But usually seems to start back up easily. Just yesturday my wife took it out to get gas and 2 minutes later dead. I eventually got it started by purging the fuel line a couple times and it fired up. I am thinking the fuel regulator which I cant find anywhere. No lights ever come up when it happens. There were old codes saying coil, o2 sensor which were replaced. This is my third coil and second fuel pump. PLEASE HELP I am starting to lose my mind.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
The fuel pressure regulator is on the fuel rail and has a vacuum line to the intake, but Im not sure if that is it. When it dies adnwont start back up (before you purged the fuel lines) what was missing? Did it have spark? Fuel pressure? I have sen the ASD (auto shutdown relay) act strange when they get hot and cant handle the current draw through them. Has it set any newer codes since you cleared the coil and o2 codes?
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
TROOPER 1
  • MEMBER
  • 6 POSTS
Actually my 96 doesnt have the fuel regulator on the fuel rail, mine unfortunately is in the tank. I am pretty sure there isnt a return line as well. Last night before I asked for help I removed the rail to blow out the fuel line all the way back and tried cleaning the injectors on the outside. Speaking of relays about a year ago it stalled and woundnt start and found out the fuel relay blew out. I replaced it for my wife and a mile down the street it blew again and replaced it with one out of my 99 and drove it home. Since then no more blown relays for the fuel. At that time I replaced the fuel pump the first time. I dont really think the problem is relay related. Just the other day iI purged the fuel line and it fired up to get it home as quick as possible. Is it it possible that the fuel relay is wired to the fuel regulator. If the regulator sometimes hickups I could see how that could heat up the relay. Does the ignition coil and o2 sensor share a common wire with the regulator? Those Chiltons and Haynes only tell basic stuff and never tell you really how to test things. Thank you for your help it is very appreciated.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Exactly what Jeep Cherokke is it and what is the 8th digit of the vin #?
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
TROOPER 1
  • MEMBER
  • 6 POSTS
The 8th digit is an S and it is a sport. Thanks for the quick reply.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
The ASD relay powers up the fuel pump relay and the ignition/coil circuit, ECM. Send me back your email adn I will send you the diagrams for the ECM wiring, If I post them here you probably wont be able to read them
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
TROOPER 1
  • MEMBER
  • 6 POSTS
My email is kimmielz1@hotmail. Com
Thank you for the info and I'll get back to you tonight.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
TROOPER 1
  • MEMBER
  • 6 POSTS
Looking forward to youe E-mail. As of now I cant even get the fuel pump to prime.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
TROOPER 1
  • MEMBER
  • 6 POSTS
Well I have spark.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
RWBRANTON
  • MEMBER
  • 4 POSTS
  • JEEP CHEROKEE
Hi there, lately I have been having problems with my 1994 Jeep Grand Cherokee, 4 liter. Sometimes when I come to a light the rpms drop really low like I am going to stall. It doesn’t stall but it feels like its coming.

I can reproduce the symptoms by holding my foot on the brake and slightly tapping the accelerator, when the Rpms jump up they immediately fall really low like around 200. I have done some things to try and help, first I have:

1. Ran good gas through, with fuel injector cleaner
2. Changed the oil
3. Cleaned the throttle body.
4. Tested the battery Passed
5. Tested the alternator which failed with my little tester, is shows that there is something wrong with my alternator, it shows in the red, but barely. Everything still works the lights aren’t dim or anything.....

So could the alternator be causing my problems? Or something else? Any ideas. I am thinking of changing the fuel filter.

Thanks for your ideas.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)
Tiny
RELLIKNIKCUF
  • MEMBER
  • 53 POSTS
I would suggest looking for a vacuum leak. If your exhaust isn't too loud, you can hear it as a hissing noise when the motor is running.
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Monday, January 11th, 2021 AT 10:50 AM (Merged)

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