Stall at idle issue

[SouthernTJ2000]

So this will be winded, however, I'm at a loss. I've read almost every post over the past two weeks on this issue. 2000 Jeep TJ 4.0 5spd. Once it's warmed up, it dies after 15-45 seconds of being at a complete stop. It'll start right back up with no issue. If I hold the RPM' (600-800) myself at a stop, it will not die. It drives fine, it idles fine (when idling), it does not jerk, snort, fart, burp, or anything. It all started about 8 months ago. I had the dreaded long start. Did some research and saw it was probably the fuel pump. It's not my daily driver, so I was in no hurry to replace it. Fast forward to earlier this year, and it started the stalling issue. Figured it was associated with the fuel pump. Replaced the fuel pump, long crank fixed, but stalling is still present. Researched and researched and researched. Here is what I have done so far:

No CEL or stored codes
New battery (battery reads over 12V when off and reads 14.XX when running)
Cleaned all grounds and terminals
Cleaned the throttle body and IAC, no dice
Replaced IAC, no dice
Replaced crank position sensor, no dice
Replaced TPS, no dice
Replaced spark plugs, would idle longer. So I put the stock sensors back on, minus the CPS as it was damaged during removal. It ran perfectly for two days. This morning, it went back to stalling every 15-45 seconds once I come to a complete stop.

I'm going to check the fuel pressure next, however, I figured if the fuel pump was giving me issues again, I'd have the long crank. I'm baffled as to why it would run flawlessly for two days, then start the same issue all over again. Talk to me folks, help me find my sanity. I'm ready to burn this thing to the ground. Thanks.

 

[Obi-Wan]

Check your plug wires and coil packs. Coils can short when when they get hot, and plug wires degrade over time.

 

[SouthernTJ2000]

Check your plug wires and coil packs. Coils can short when when they get hot, and plug wires degrade over time.

Mine has the single "coil pack" contraption. It "looked" okay when I replaced the plugs, however, that's on the short list as well.

 

[macleanflood]

Ohm check the coil. Might as well do the injectors while you're in there.

-Mac

 

[harmd]

2012 Jeep Wrangler 180K total with Jasper 3.6 with ~30K on it. Had same issue as OP dying at idle especially when warm. Threw no codes. For what its worth, just replaced crankcase position sensor and it appears to be resolved. Note, the shop put in non OEM sensor during engine replacement and it must have failed at low mileage. Replacced with OEM sensor.

 

[SouthernTJ2000]

Just thought I'd update this. Turned out to be the coil cassette.

 

[lBasket]

Just thought I'd update this. Turned out to be the coil cassette.

The cassette!! I thought that was a Saab term

 

[RangerTJ]

The cassette!! I thought that was a Saab term

I'm just glad it wasn't the coil 8-track!

On a side note:

When mine was stalling at idle it turned out to be the big vacuum hose on the side of the intake manifold.

It looked fine but when I touched it it crumbled to powder.

 

[SouthernTJ2000]

The cassette!! I thought that was a Saab term

I believe it is, however when I think coil pack, I always think one of many. I wasn't sure what else to call it. Thought coil block, but just didn't like the way it sounded in my head. Coil Case...Coil Conex Box...Coil Housing...lol

 

[Obi-Wan]

Check your plug wires and coil packs. Coils can short when when they get hot, and plug wires degrade over time.

Just thought I'd update this. Turned out to be the coil cassette

 

[hear]

Oh no, you’re not taking credit for the cassette.

 

[bohuggabee]

So this will be winded, however, I'm at a loss. I've read almost every post over the past two weeks on this issue. 2000 Jeep TJ 4.0 5spd. Once it's warmed up, it dies after 15-45 seconds of being at a complete stop. It'll start right back up with no issue. If I hold the RPM' (600-800) myself at a stop, it will not die. It drives fine, it idles fine (when idling), it does not jerk, snort, fart, burp, or anything. It all started about 8 months ago. I had the dreaded long start. Did some research and saw it was probably the fuel pump. It's not my daily driver, so I was in no hurry to replace it. Fast forward to earlier this year, and it started the stalling issue. Figured it was associated with the fuel pump. Replaced the fuel pump, long crank fixed, but stalling is still present. Researched and researched and researched. Here is what I have done so far:

No CEL or stored codes
New battery (battery reads over 12V when off and reads 14.XX when running)
Cleaned all grounds and terminals
Cleaned the throttle body and IAC, no dice
Replaced IAC, no dice
Replaced crank position sensor, no dice
Replaced TPS, no dice
Replaced spark plugs, would idle longer. So I put the stock sensors back on, minus the CPS as it was damaged during removal. It ran perfectly for two days. This morning, it went back to stalling every 15-45 seconds once I come to a complete stop.

I'm going to check the fuel pressure next, however, I figured if the fuel pump was giving me issues again, I'd have the long crank. I'm baffled as to why it would run flawlessly for two days, then start the same issue all over again. Talk to me folks, help me find my sanity. I'm ready to burn this thing to the ground. Thanks.

Could be back pressure and heat soaking. Does it do it if the hood is open? And when you hear it start to bog down. Does throttle fail? Or does it keep it running? Which could be the throttle body sensor failing if im not mistaken. My tj idles at 900. So maybe you need to reset the computer. Try warming the engine. Reset computer. The older ones get temperamental about humidity and stuff. As the o2 sesnors age. They need to be cleaned too.

So warm it up. Let it die. Unplug battery positive. Turn on your lights. Wait 30 seconds. Turn off lights. Put positive back on. Start jeep.