1997 Jeep Cherokee Engine idle issues

Tiny
SEAP
  • MEMBER
  • 1997 JEEP CHEROKEE
  • 6 CYL
  • 4WD
  • MANUAL
  • 184,000 MILES
Ill just be driving along (approximately 2 miles or more) when I have a problem with the engine idling. It seems to occur after the engine has warmed up and the oil has circulated, Im not sure. If Im driving on the highway, stop pressing down the gas pedal and disengage the clutch, the RPMs will shoot up. The range on the dashboard goes from 0 to 6000 RPMs, and when the problem happens, it will automatically rise about 2000 RPMs higher than where it currently is at the moment. After I come to a stop, the idle process will settle at around 1000 RPMs (800 RPMs is what I have noticed to be normal). When this happens, the moment I give it more gas, the vehicle dies. After it has died, it will not start again until about 20 minutes later (it wont even start when I put starting fluid in the intake manifold). I can tap the gas pedal just enough to not kill the vehicle, wait 2 seconds later when the RPMs shoot up again, then give it more gas at that moment and Ill be able to drive along again. I have replaced the idling position sensor twice now (within the past year). I have also replaced the oil and O2 sensor recently. Do you know or have any suggestions on how to fix my problem?
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Thursday, October 1st, 2009 AT 11:32 PM

7 Replies

Tiny
RACEFAN966
  • EXPERT
Well what I would check the temp sensor and air charge temp sensor. Now the temp sensor is not in a fun spot. You need to remove the air filter box and it is located next to the engine mount. The air charge temp sensor is on the intake. If you have a digital multi meter then unplug them and check the ohms. The ohms should be the same between the two. Do this when the engine is cold and get back to me with the ohms readings and the air temp at the time of the test and I will let you know if one of them is bad.
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Friday, October 2nd, 2009 AT 9:30 AM
Tiny
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  • MEMBER
I tested the sensor attached to the manifold. It seems to be working just fine. I set my volt meter on 20k ohms and touched the sensor part. The numbers on the meter proceeded to go down.


http://www.2carpros.com/forum/automotive_pictures/411849_PA030686_1.jpg



I cannot find the Intake Air Temp sensor. You said it was located next to the engine mount, but I have looked high and low and I cannot find it. Could you direct me as to where it is?


http://www.2carpros.com/forum/automotive_pictures/411849_PA030688_1.jpg



http://www.2carpros.com/forum/automotive_pictures/411849_PA030689_3.jpg



http://www.2carpros.com/forum/automotive_pictures/411849_PA030690_2.jpg

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Saturday, October 3rd, 2009 AT 4:03 PM
Tiny
RACEFAN966
  • EXPERT
That is the Air Charge Temp Sensor. Now you say it is 20k at what temp? The temp is very import in determining if it is good or not. Now the Engine Temp sensor is the one you are trouble finding. That is my bad I sent you in the wrong area. Sorry I looked at a 96 not a 97. It is on the thermostat housing. Here is pic to help. I need the ohm readings and the temp at the time of the readings. So if you check them cold get me ohms and air temp at time of test. Like I meantioned they should match or be very close to hte same ohms.


http://www.2carpros.com/forum/automotive_pictures/249564_Graphic_138.jpg

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Monday, October 5th, 2009 AT 6:05 PM
Tiny
SEAP
  • MEMBER
Air Charge Sensor :
Ohms - 10.69
Temp - 70 - 73 F/ Room Temp

Engine Temp Sensor:
Ohms - 11.07
Temp - 70 - 73 F/ Room Temp
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Wednesday, October 14th, 2009 AT 9:57 AM
Tiny
RACEFAN966
  • EXPERT
Ok the Air charge temp is good and in spec. The Coolant temp sensor it out of spec and should be replaced but I don't think it is out of range enough to cause you high idle. Have you checked for intake manifold leaks? Have you don't any tune up stuff to the Jeep? I would also like to check the Idle Air Control Motor. I would like to unplug it and see if it changes how it runs. Then I would like you to remove it and clean it with throttle body cleaner and clean out the throttle body where the motor is attached. Let me know what you find.
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Wednesday, October 14th, 2009 AT 10:26 AM
Tiny
SEAP
  • MEMBER
First off, the Jeep seems to be running a lot better after I pulled both the engine temp and air charge sensors and cleaned them a bit. I haven't had a problem since. So I decided to still do what you asked me to do.
I started the car, let it run about a min and then unplugged the Idle Air Control Motor. Nothing happend. I shut off the car, unscrewed it and pulled it out. The entire motor was black on the inside with I guess would be char and the housing was as well. I cleaned them both with STP throttle body cleaner and put them back in place. The jeep seems to get a lot more power than before and still isn't having the issue that it was having. Could it be that the sensors just needed cleaning?
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Friday, October 16th, 2009 AT 10:57 AM
Tiny
RACEFAN966
  • EXPERT
Yes very well could have it also could be that just unplugging them was the fix. It may not have had a clean connection. Any how sounds like you are back in business. If you have any other problems or questions just ask. Thanks and have a great day.
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Saturday, October 17th, 2009 AT 8:39 AM

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