1998 Jeep Grand Cherokee stalling while driving
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Newbie
Joined: Jun 2017
Posts: 9
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Model: Cherokee
1998 Jeep Grand Cherokee stalling while driving
I have a 1998 Jeep Grand Cherokee. I have noticed some issues starting a few months ago, a little hesitation while driving upon acceleration. I have brought a OBD code reader, and it gave me a code PO720. I have since fixed that issue but the main issue I have still persists. Stalling while driving, and low idle coming to a stop, or sitting in traffic at a red light. Idle starts out at 1000 RPM, then goes down to 500, or even 300 when I put it in gear or when driving. Can you guys help I'am pulling what little hair I have left out.
CF Veteran
Joined: May 2010
Posts: 1,175
Likes: 31
From: Boston
Year: 2000
Engine: 4.7L
It'll help to know a little more detail about your Jeep and drive conditions. Is you typical drive all local or highway and at what speed/duration? Which engine and transmission? How many miles are on it? Any major rework within the last 12k miles?
Your description of the problem points at the Throttle Body, Throttle Position Sensor (TPS), Idle Air Controller (IAC) or a vacuum leak.
How did you fix the P0720? Did you just replace the output shaft speed sensor? Did you use an OEM part? I ask this because that "issue" isn't really fixed just yet, as there is a relationship to your present condition. Also, if the sensor was not OEM then it may be the cause of the erratic throttle/idle.
Clean the Throttle Body and *IAC then drive a little to gauge the effect of a clean intake. (Pick up a new TPS (just in-case) while you're out on the test drive.)
*NOTE: Special cautions are to be observed when servicing the IAC as it is a semi-fragile component. Do a little research before attempting that. You'll see what I mean.
If you still experience stumbles/stalls then spray direct spritzes of Throttle Body Cleaner around the base of your throttle body while listening for changes to idle that you can associate with having sprayed at a particular spot. Repeat same around the intake manifold gasket and any fittings connected to the manifold. Changes in idle quality caused by spraying around gaskets are indications of vacuum leaks. The manifold gasket will need to be replaced but sometimes the TB gasket can be reused - I have done this but I think I got lucky - need more feedback to confirm if that's a good/bad idea.
If it the condition was resolved by cleaning or you know for sure that there's a vacuum leak then return the unopened/unused TPS to the store. If the condition persists then replace the TPS.
Hope this helps. It shouldn't be too tough to deal with but get help if you're unfamiliar with this stuff. Good luck.
Your description of the problem points at the Throttle Body, Throttle Position Sensor (TPS), Idle Air Controller (IAC) or a vacuum leak.
How did you fix the P0720? Did you just replace the output shaft speed sensor? Did you use an OEM part? I ask this because that "issue" isn't really fixed just yet, as there is a relationship to your present condition. Also, if the sensor was not OEM then it may be the cause of the erratic throttle/idle.
Clean the Throttle Body and *IAC then drive a little to gauge the effect of a clean intake. (Pick up a new TPS (just in-case) while you're out on the test drive.)
*NOTE: Special cautions are to be observed when servicing the IAC as it is a semi-fragile component. Do a little research before attempting that. You'll see what I mean.
If you still experience stumbles/stalls then spray direct spritzes of Throttle Body Cleaner around the base of your throttle body while listening for changes to idle that you can associate with having sprayed at a particular spot. Repeat same around the intake manifold gasket and any fittings connected to the manifold. Changes in idle quality caused by spraying around gaskets are indications of vacuum leaks. The manifold gasket will need to be replaced but sometimes the TB gasket can be reused - I have done this but I think I got lucky - need more feedback to confirm if that's a good/bad idea.
If it the condition was resolved by cleaning or you know for sure that there's a vacuum leak then return the unopened/unused TPS to the store. If the condition persists then replace the TPS.
Hope this helps. It shouldn't be too tough to deal with but get help if you're unfamiliar with this stuff. Good luck.
Thread Starter
Newbie
Joined: Jun 2017
Posts: 9
Likes: 0
Model: Cherokee
Response
I have cleaned the throttle body, and the IAC. I might have to take it off to clean the underside, at the minor expense of replacing the gasket. I already figured it being the TPS, and the truck does shift better with the new output Speed Sensor. I didn't think that would fix the idle problem, but that's what the reader indicated. I ran the code reader again and that PO720 code didn't show up. My truck has 277,000 plus as far as mileage with mainly local driving to and from work. I'am the second owner. Most of the time I don't go over 40mph. I'll get back to you with the engine specs.
Thread Starter
Newbie
Joined: Jun 2017
Posts: 9
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Model: Cherokee
Update
It'll help to know a little more detail about your Jeep and drive conditions. Is you typical drive all local or highway and at what speed/duration? Which engine and transmission? How many miles are on it? Any major rework within the last 12k miles?
Your description of the problem points at the Throttle Body, Throttle Position Sensor (TPS), Idle Air Controller (IAC) or a vacuum leak.
How did you fix the P0720? Did you just replace the output shaft speed sensor? Did you use an OEM part? I ask this because that "issue" isn't really fixed just yet, as there is a relationship to your present condition. Also, if the sensor was not OEM then it may be the cause of the erratic throttle/idle.
Clean the Throttle Body and *IAC then drive a little to gauge the effect of a clean intake. (Pick up a new TPS (just in-case) while you're out on the test drive.)
*NOTE: Special cautions are to be observed when servicing the IAC as it is a semi-fragile component. Do a little research before attempting that. You'll see what I mean.
If you still experience stumbles/stalls then spray direct spritzes of Throttle Body Cleaner around the base of your throttle body while listening for changes to idle that you can associate with having sprayed at a particular spot. Repeat same around the intake manifold gasket and any fittings connected to the manifold. Changes in idle quality caused by spraying around gaskets are indications of vacuum leaks. The manifold gasket will need to be replaced but sometimes the TB gasket can be reused - I have done this but I think I got lucky - need more feedback to confirm if that's a good/bad idea.
If it the condition was resolved by cleaning or you know for sure that there's a vacuum leak then return the unopened/unused TPS to the store. If the condition persists then replace the TPS.
Hope this helps. It shouldn't be too tough to deal with but get help if you're unfamiliar with this stuff. Good luck.
Your description of the problem points at the Throttle Body, Throttle Position Sensor (TPS), Idle Air Controller (IAC) or a vacuum leak.
How did you fix the P0720? Did you just replace the output shaft speed sensor? Did you use an OEM part? I ask this because that "issue" isn't really fixed just yet, as there is a relationship to your present condition. Also, if the sensor was not OEM then it may be the cause of the erratic throttle/idle.
Clean the Throttle Body and *IAC then drive a little to gauge the effect of a clean intake. (Pick up a new TPS (just in-case) while you're out on the test drive.)
*NOTE: Special cautions are to be observed when servicing the IAC as it is a semi-fragile component. Do a little research before attempting that. You'll see what I mean.
If you still experience stumbles/stalls then spray direct spritzes of Throttle Body Cleaner around the base of your throttle body while listening for changes to idle that you can associate with having sprayed at a particular spot. Repeat same around the intake manifold gasket and any fittings connected to the manifold. Changes in idle quality caused by spraying around gaskets are indications of vacuum leaks. The manifold gasket will need to be replaced but sometimes the TB gasket can be reused - I have done this but I think I got lucky - need more feedback to confirm if that's a good/bad idea.
If it the condition was resolved by cleaning or you know for sure that there's a vacuum leak then return the unopened/unused TPS to the store. If the condition persists then replace the TPS.
Hope this helps. It shouldn't be too tough to deal with but get help if you're unfamiliar with this stuff. Good luck.
Seasoned Member
Joined: Dec 2010
Posts: 350
Likes: 0
From: Georgia, USA
Year: 1994
Model: Grand Cherokee
Engine: v8
Take off both battery terminals and clean them. The CPS needs the battery voltage to be constant, or some such witchery, and a little crud on the posts will cause mayhem.
Hear me now, believe me later. And its a free "fix".
Hear me now, believe me later. And its a free "fix".
Thread Starter
Newbie
Joined: Jun 2017
Posts: 9
Likes: 0
Model: Cherokee
response to rangermonroe, I fixed the problem. It was a bad TPS. Thank you anyway
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Old fart with a wrench
Joined: Nov 2010
Posts: 14,398
Likes: 740
From: Manlius, east of Syracuse, NY
Year: 2000 XJ Sport & WJ Laredo
Model: Grand Cherokee (WJ)
Engine: 4.0L
No, it's not hard to change but you need to be careful and not force anything, and yes, use Mopar parts for quality, durability and long life. Check out YouTube videos about how to do it. It's just a plug and 2 screws.