Jeep stalling at idle - JeepForum.com
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post #1 of 13 Old 01-19-2020, 12:37 PM Thread Starter
JGCJeep
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Jeep stalling at idle

2001 4.0

I just went out to lunch and the Jeep wouldn’t idle. Ran fine when I held my foot on the gas and started fine. It idled fine after it warmed up.

Any ideas?

What controls the idle in these things?

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post #2 of 13 Old 01-19-2020, 01:32 PM
jtec
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a scanner would really help here- looking at live data.
some ideas might help narrow checking.

Is Airbag light on?
Did you try the key on off trick for codes?
Holding throttle open suggests to me a RICH condition.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #3 of 13 Old 01-19-2020, 01:46 PM Thread Starter
JGCJeep
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Quote:
Originally Posted by jtec View Post
a scanner would really help here- looking at live data.
some ideas might help narrow checking.

Is Airbag light on?
Did you try the key on off trick for codes?
Holding throttle open suggests to me a RICH condition.
No airbag light.

I did not try the code trick.

Would a rich condition stall it immediately at idle when cold? It ran perfect when I had my foot on the gas and kept it at 1000 rpm.

Murphys Law. I’m at work and my scanner’s at home. I’ll monitor the live data later or tomorrow.

I was just reading through the sheets on how it’s all set up. If it keeps doing it I’ll clean stuff up on the throttle body and if I read right, the IAC resets and relearns after power is disconnected, so I’ll try that too.
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post #4 of 13 Old 01-19-2020, 01:58 PM
jtec
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Always cleaning TB and IAC is a good idea, google youtube for a tutorial* if needed.
As I posted I think holding TB open suggests RICH.
The key on off is a good start but a scanner is the go to tool.


* "cleaning jeep IAC"

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #5 of 13 Old 01-19-2020, 02:05 PM Thread Starter
JGCJeep
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Quote:
Originally Posted by jtec View Post
Always cleaning TB and IAC is a good idea, google youtube for a tutorial* if needed.
As I posted I think holding TB open suggests RICH.
The key on off is a good start but a scanner is the go to tool.


* "cleaning jeep IAC"
Will do. Thank you for the advice. 🙂
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post #6 of 13 Old 01-20-2020, 09:14 AM
Bigrigr
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Another quick thing to check is the battery connections. My jeep did this the other day, and it turned out that the previous owner had incorrectly installed clamp on battery cable ends and they were loose. I had to remove the cables, touch the two cables together(off the battery in the air of course) to drain any residual captive juice in the system, then reinstall correctly. Once i did this, my starting/ idling issues ceased. Been good for about two weeks now.... Make sure your battery connections are clean and tight. Best way to do this is to remove them, clean and reinstall. Many time you can have a bit of corrosion in between the cable end and the battery post you can see until you get the cables removed. There is a specific battery post/cable wire brush available that helps make quick work of this.

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post #7 of 13 Old 01-20-2020, 10:45 AM Thread Starter
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Originally Posted by Bigrigr View Post
Another quick thing to check is the battery connections. My jeep did this the other day, and it turned out that the previous owner had incorrectly installed clamp on battery cable ends and they were loose. I had to remove the cables, touch the two cables together(off the battery in the air of course) to drain any residual captive juice in the system, then reinstall correctly. Once i did this, my starting/ idling issues ceased. Been good for about two weeks now.... Make sure your battery connections are clean and tight. Best way to do this is to remove them, clean and reinstall. Many time you can have a bit of corrosion in between the cable end and the battery post you can see until you get the cables removed. There is a specific battery post/cable wire brush available that helps make quick work of this.
Thank you! I didn’t even thing about the battery. It’s clean, but I had it disconnected the other day.
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post #8 of 13 Old 01-20-2020, 10:45 AM Thread Starter
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It started fine when I went home last night and did it again this morning.
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post #9 of 13 Old 01-21-2020, 05:54 PM
lostlikemy10mm
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Always checking intake vacuum leaks is also a good way to eliminate idle issues. Spraying brake clean around all the intake and intake manifold hoses to see if idle speed changes can be a good indicator of a vacuum leak. And as others have said check Crank position sensor IAC MAP TPS IAT and wiring to all of them. There are good videos out there of where those sensors are and what they do.

Blooop Bloop Bloop
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post #10 of 13 Old 01-21-2020, 06:03 PM
LJ_Comm
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Brake cleaner is caustic stuff and will degrade rubber and plastics. For a vacuum leak try disconnecting and reconnecting the lines first listening for a change in rpms, engine noise.
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post #11 of 13 Old 01-21-2020, 07:41 PM
Martineze333
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I've ran into this multiple times over the years with my WJ 4.0 and found on separate occasions separate issues. The first was the battery not having a good charge and cables being ever so slightly loose. Hard to find when not thinking about a loose connection causing an idle problem. Cleaned them with wire brush and reconnected nice and tight, problem solved. Second time and multiple time since I had issues with the idle air control valve not working well. Same as the battery problem if I drove it for a while keeping it running at stop signs with the gas pedal not would be fine for the second half of the day. My fix was removing the IAC valve and cleaning it out with proper intake spray cleaner. Good time to clean throttle body as well. Good luck with your search!!
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post #12 of 13 Old 01-22-2020, 05:40 PM Thread Starter
JGCJeep
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It was the idle air control valve. It was shot.

Thank you everyone for the advice.
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post #13 of 13 Old 01-23-2020, 10:43 AM
lostlikemy10mm
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Nice! glad to hear you're back to normal running again. Always a good feeling.

Blooop Bloop Bloop
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