Will not idle after it is warm

Tiny
ABCAUTO
  • MEMBER
  • 2003 JEEP LIBERTY
  • 3.7L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 128,000 MILES
I have a 2003 jeep liberty that will not idle after it is warm (5 min). It will run perfect going down the road, will die at the stop sign. NO CODES I have changed the plugs, camshaft sensor, crank sensor, engine temperature control sensor, the idle air control motor, cleaned the throttle body. Can someone tell me what is my problem?
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Tuesday, January 28th, 2014 AT 1:31 PM

15 Replies

Tiny
KNOWLEDGE IS POWER
  • EXPERT
You should check fuel pressure and service the fuel filter if you haven't already. Its right on the front of the fuel tank. Also you might benefit from a possible reflash of the ecm at the dealer. Since there aren't any codes and because of the work you've done im inclined to believe this or you may even have a bad idle air control valve. There aren't any technical service bulletins on this subject. That's good. Make sure also that all the vacuum lines are in place and in good condition. Don't forget to check your air filter and intake tube for obstructions
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Tuesday, January 28th, 2014 AT 2:00 PM
Tiny
ABCAUTO
  • MEMBER
I replaced the idle air control (motor), is that the same as the idle air control valve. The vacuum lines are all good, no leaks. Air filter and intake tube are ok. I have reflashed the ecm. I was told by the parts house that the fuel filter in not serviceable. I will do some more research.
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Tuesday, January 28th, 2014 AT 2:29 PM
Tiny
ABCAUTO
  • MEMBER
I checked the fuel pressure. It holds steady at 50 lbs of pressure.

I started the engine, it idled fine at 1000 rpm's for about 10 - 15 minutes, it gradually worked its way down to about 600, then started fluctuating and then quit. Help me. Could it be the throttle position sensor?
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Tuesday, January 28th, 2014 AT 3:28 PM
Tiny
ABCAUTO
  • MEMBER
I checked the fuel pressure on the 2003 liberty, it is good holds steady at 50 lbs. I started the engine, it idled fine at 1000 rpm's after about 10-15 minutes it started working its way down to about 600 and then started fluctuating from 500 to 1000 and then quit. The fuel pressure was steady at 50 lbs. I replaced the idle air control (motor). Is this the same as the idle air control valve. No vaccum leaks or air intake obstructions.
I also forgot to mention that I also did a compression test. Was good
I have reflashed the ecm. Help me. Could it be the throttle position sensor.

Darrell
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Tuesday, January 28th, 2014 AT 4:02 PM
Tiny
KNOWLEDGE IS POWER
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It could be the throttle position sensor. It could be a crank position sensor. If you've not had the timing belt replaced it might be time to consider that. A good shop with a decent diagnostic computer should be able to read the cam and crank sensor data and be able to tell some of these things.
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Wednesday, January 29th, 2014 AT 3:03 PM
Tiny
ABCAUTO
  • MEMBER
I have replaced the crank sensor.

About the only thing that I haven't replaced is the throttle position sensor.
I am debating whether to go ahead and replace it, , I thought a faulty throttle position sensor would set a code?
How could the timing belt affect the idle? If you think it is a good possibility, I will replace it.
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Wednesday, January 29th, 2014 AT 8:45 PM
Tiny
KNOWLEDGE IS POWER
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A faulty throttle position sensor should set a code. If you haven't ever replaced the timing belt id do it simply because its time. It can affect idle because of slack and or stretch making the timing fluctuate at idle. It can be checked first if youre unsure. May as well have the throttle position sensor at the same time if you take the vehicle to a shop
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Thursday, January 30th, 2014 AT 4:18 PM
Tiny
ABCAUTO
  • MEMBER
Thank you for responding,

I was told the 3.7 liter that I have has a timing chain. I guess the 4 cyl has a belt. So, my question would be. Should I replace the timing chain? The vehicle runs good until it is warmed up.
I will replace the throttle position sensor. I might as well, I have replaced
about every other sensor.

Darrell
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Tuesday, February 4th, 2014 AT 1:58 PM
Tiny
KNOWLEDGE IS POWER
  • EXPERT
Hey sorry about the misinfo about the belt I thought you had 4 cyl. Don't replace the timing chain just yet. Im curious as to what temp the ECM is reading when the vehicles warmed up and if its leaning out the fuel system because of a false reading. These kinds of problems are difficult to diag like this. Whenthe vehicle is at full temp and stumbling, unplug the coolant temp sensor and see if it runs different.
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Tuesday, February 4th, 2014 AT 2:39 PM
Tiny
JEEPPROBLEMS18
  • MEMBER
Hey Darrell did you figure out why it was doing that I have the same exact Jeep and mine started doing that but I can t figure out what s wrong with it it s like if I keep giving it gas it will stay on but if I don t it shuts off help please
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Wednesday, November 28th, 2018 AT 12:08 PM
Tiny
KEN
  • ADMIN
It sounds like the PCM is bad because there are no codes which there should be if it can control idle. I would get a used/rebuilt one and try that. Here is a guide that can help as well.

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

I have also seen engine coolant temperature sensors do this as well. They wont set a code either because it is not shorted or open. Here is a guide and the location in the diagrams below for your car.

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Check out the diagrams (Below). Please let us know what happens.

Cheers, Ken
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Friday, November 30th, 2018 AT 3:06 PM
Tiny
JEEPPROBLEMS18
  • MEMBER
Yeah, it idles fine when you first start it, but once you drive and go to stop it shuts off. If you keep giving it gas it will run.
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Saturday, December 1st, 2018 AT 11:44 AM
Tiny
KEN
  • ADMIN
Yep, I have seen coolant sensors cause this or a vacuum leak. Check out this guides as well:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know
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Sunday, December 2nd, 2018 AT 10:31 AM
Tiny
JEEPPROBLEMS18
  • MEMBER
Okay, I am going to try the coolant sensor since a code popped up that says thermostat malfunction. So I will start there and pray it works.
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Sunday, December 2nd, 2018 AT 3:17 PM
Tiny
KEN
  • ADMIN
Okay let us know.
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Monday, December 3rd, 2018 AT 9:23 AM

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