Automatic 4.0 stalling when cold / warming up. 2000 California emissions.

[Rick'sTJ2000]

Hello everyone,

Started having this problem with my Jeep on first drive, it has an idle drop issue and will stall if I sit at a red light or stop sign for too long. After driving and the coolant temp. comes to normal range everything is fine, and the Jeep idles normal.

- Replaced the CPS - no change.
- Replaced the TPS, better idle than before but didn't solve the issue.
- Cleaned IAC, followed the forum's instructions on how-to. No change.

My next course of action was going to be to unplug the 2 upstream O2 sensors to see if this is what's driving the issues. They were recently replaced by a Jeep mechanic here on Long Island in the summer when an engine check light came on (came on after I had a bunch of work done, brake lines, transmission lines, next exhaust (only muffler and exhaust pipe, didn't touch Catalytic convertors).

I have attached a couple of videos too better help understand what I'm facing.

First drive of the day, let it warm up for about 10 mins to see if it would help but to no avail.

https://imgur.com/hXBA4zc

This is me restarting the car after it stalled, as you can see after a few seconds the idle drops then picks back up. if I don't put it in neutral the engine will die. Usually this will occur before it stalls, but this morning it didn't even fight, just died.

https://imgur.com/52IwcFC

This is after driving about 5 - 10 minutes (4-5 miles), idling perfect at a red light. Coolant temp at optimal range.

https://imgur.com/00LONiF

Any help would be appreciated! this forum has come to my aid more than a handful of times, created a profile just now because I can't find a solution for this issue.

 

[macleanflood]

Do you have the ability to read live ODB data...a $25-$30 Bluetooth dongle and the free app Torque Lite would do it...

-Mac

 

[Rick'sTJ2000]

Yep, i picked one up from Harbor Freight. 0 codes thrown at it.

 

[ColoJeep]

Turn your heater control all the way off and see if it does it . Your engine maybe is stalling when the A/C compressor kicks in before the engine is warned up.

 

[RMETeeJay]

Even though no O2 codes, it's possible that they used a brand/model that isn't compatible. Verify the correct sensors here:

Thread 'The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread'

Mar 5, 2017

What are Bank 1, Bank 2, etc.?
Since this question pops up from time-to-time, here's an easy to follow diagram that illustrates what they mean when your OBDII code scanner (or manual) tells you something like "O2 sensor, Bank 1, Sensor 2":

What does upstream and downstream mean?
Simple, upstream means the O2 sensor is "upstream" of the catalytic convertors, meaning before the catalytic convertors. Downstream means the O2 sensor is "downstream" of the catalytic convertors, meaning after the catalytic convertors.


What brand of...

• Chris
• bank 1 bank 2 catalytic convertor cats emissions o2 sensor oxygen sensor sensors
• Replies: 1,045
• Forum: TJ Resources

• 
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I would also replace all O2s at one time vs only the upstream. They are a wear item and directly affect drivability and MPG.

If they are OK, you could try a PCM reset. I recommend it whenever replacing FI sensors so that it can do a relearn cycle (more details on that in the FSM):

Post in thread 'Any benefit to resetting PCM?'

Nov 20, 2018

I think it's a good thing to reset the PCM every other year or when you replace sensors, regear, or change what fuel octane you use.

I reset mine after regering and got rid of the pinging I was experiencing at very low revs when loading it up the my 4.0L

For the record - as someone is bound to ask...

1. Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds to discharge the PCM capacitors, which maintain the Adaptive Memory.
2. Reconnect the Battery Cable.
3. Turn Ignition Switch to the “On” position but DO NOT start the engine.
4. Turn Headlight On.
5. Turn...

• Wombat

• 

 

[Rick'sTJ2000]

Ty all, I will try to see if it's the heat, but I don't think this is the cause as I don't always have it on in the mornings. I will be testing out the 02 sensors first and if that doesn't do it will perform a PCM reset.

 

[macleanflood]

Yep, i picked one up from Harbor Freight. 0 codes thrown at it.

Not exactly what I'm suggesting...what you need to do is look at O2 sensor voltages, fuel trims. Possibly idle or what the PCM thinks the RPM is, IAT and others.

We're not looking for codes...just clues...

-Mac

 

[Rick'sTJ2000]

Understood thanks for clarifying, the O2 sensors were going to be my next thing to check but wanted to come here and confirm before doing so. I actually called my mechanic today to verify the brand they used, and they confirmed they put in Denso O2 sensors.

 

[RMETeeJay]

It’s recommended to use the NTK sensors for CA emissions specified in the above link.

2000 (California Emissions)
NTK #23179 - Bank 1, Sensor 1 (Upstream)
NTK #23506 - Bank 2, Sensor 1 (Upstream)
NTK #23110 - Bank 1, Sensor 2 (Downstream)
NTK #23179 - Bank 2, Sensor 2 (Downstream)

 

[Rick'sTJ2000]

Update for anyone facing similar issues, this was caused by Low transmission fluid. I am guessing this caused the torque converter to stall the vehicle at low temps. Filled it up with ATF and stall went away, peeked under the car and there is a small leak near the transfer case so going to have to check that out. Hopefully this didn't cause unwanted damage to the transmission.