TJ stalled in traffic

[ItchyDong]

When we had a crank sensor problem at Mercedes in the early 2000s this worked like a champ until we figured out the bad part #s that were affected. And no, these rarely set a code.
When the sensor gets hot and expands, the circuit goes open. When it cools off, the circuit makes contact again.
This is more common with inductive sensors, but heat can reproduce a failure mode in other types as well.

This sensor won’t test like that. Running continuity through a transistor that requires a magnetic force to pull down the circuit to make a square wave won’t work without a 5V source. It is true that heat can cause the transistor to fail. It’s quite common, but the test method is a no-go. You probably tested a permanent magnet Hall effect type sensor that makes its own voltage.

 

[justfixedthat...]

How’s the oil look? Any sparkly bits?
I don’t know the threshold on the 4.0, but if it gets too low and starves the bearings it could be starting to lock up the engine.
My sister did that to an old 318 Dodge motor. Added oil and back on the road again. That poor car....

It looked like crude oil. No sparkly bits. No other discoloration.

That's interesting. When it died it just gave out like someone pulled the plug. No sound. No warning. No sputtering. Is that what your sister experienced?

 

[justfixedthat...]

This sensor won’t test like that. Running continuity through a transistor that requires a magnetic force to pull down the circuit to make a square wave won’t work without a 5V source. It is true that heat can cause the transistor to fail. It’s quite common, but the test method is a no-go. You probably tested a permanent magnet Hall effect type sensor that makes its own voltage.

Can't say I fully understand what's being discussed here. Should I just look at it and pretend I know what I'm looking for?

 

[justfixedthat...]

How’s the oil look? Any sparkly bits?
I don’t know the threshold on the 4.0, but if it gets too low and starves the bearings it could be starting to lock up the engine.
My sister did that to an old 318 Dodge motor. Added oil and back on the road again. That poor car....

...and presumably hers bucked too?

 

[Claytone]

This sensor won’t test like that. Running continuity through a transistor that requires a magnetic force to pull down the circuit to make a square wave won’t work without a 5V source. It is true that heat can cause the transistor to fail. It’s quite common, but the test method is a no-go. You probably tested a permanent magnet Hall effect type sensor that makes its own voltage.

I stand corrected, I was thinking this was a simple 2 wire crank sensor.

 

[Claytone]

...and presumably hers bucked too?

It did, and then died and wouldn’t start again till it cooled off. Wouldn’t crank either. Found out it was almost out of oil. That car got sold off shortly after that.
I was 13 and this was in the 80s, so the details are a bit distant.
After re-reading your initial post, it sounds like yours did crank/no-start after it stalled, so hopefully you didn’t oil starve it.

 

[justfixedthat...]

It did, and then died and wouldn’t start again till it cooled off. Wouldn’t crank either. Found out it was almost out of oil. That car got sold off shortly after that.
I was 13 and this was in the 80s, so the details are a bit distant.
After re-reading your initial post, it sounds like yours did crank/no-start after it stalled, so hopefully you didn’t oil starve it.

Yeah it cranked plenty of times but wouldn't turn over. The first time it finally turned over after 20 minutes. The second and third time it started right up, but when I got it home I couldn't restart it. It eventually stopped trying - turns out the brushes were completely gone so I rebuilt the starter. The fourth time it died in traffic and wouldn't restart. I opened the starter and it was full of oil. Cleaned it and it started right up.

So I'm thinking the trouble starting is separate from the bucking/stalling.

Still sound like low oil?

 

[Claytone]

No it doesn’t.
But it does sound like a heat related sensor or component failure.

 

[justfixedthat...]

No it doesn’t.
But it does sound like a heat related sensor or component failure.

Okay. And the fact that it happened out of the blue a few weeks ago? Literally no warnings. Oh! About a week before the bucking/stalling began, the shifter wouldn't allow me to put it in Park. It's happened several times. I had to slam it into Park each time. Could those things be connected??

 

[justfixedthat...]

Got some oil today and had them check the battery/alternator. Battery was bad. But on the way there I noticed the jeep shuddering. What it felt like, and I know from experience, is the jeep was only using 4 or 5 cylinders. I wonder if I've been looking at a bad coilpack this whole time.

 

[justfixedthat...]

First explain this?
2002 Wrangler Sport
What kind of transmission is in your Wrangler? 42RLE

p.s. Have you had the alternator and battery tested?

Got some oil yesterday and had them check the battery/alternator. Battery was bad. But on the way there I noticed the jeep shuddering. What it felt like, and I know from experience, was the jeep was only using 4 or 5 cylinders (and in fact I slammed the gas and the acceleration seemed underpowered). I wonder if I've been looking at a bad coilpack this whole time.

 

[justfixedthat...]

No it doesn’t.
But it does sound like a heat related sensor or component failure.

Got some oil yesterday and had them check the battery/alternator. Battery was bad. But on the way there I noticed the jeep shuddering. What it felt like, and I know from experience, was the jeep was only using 4 or 5 cylinders (and in fact I slammed the gas and the acceleration seemed underpowered). I wonder if I've been looking at a bad coilpack this whole time. Like you said, heat has previously given me coilpack problems. I replaced it about a year ago but it was cheap.

 

[justfixedthat...]

No it doesn’t.
But it does sound like a heat related sensor or component failure.

Now it's sputtering, has low power, and a gas smell coming from the exhaust. If it's an O2 sensor, could that also cause the bucking and stalling?

 

[justfixedthat...]

No it doesn’t.
But it does sound like a heat related sensor or component failure.

New coil pack solved it. Misfiring caused it to run rich and cause the pending catalytic converter code. Drives great now. I'll double check everything. Thanks.

 

[justfixedthat...]

This sensor won’t test like that. Running continuity through a transistor that requires a magnetic force to pull down the circuit to make a square wave won’t work without a 5V source. It is true that heat can cause the transistor to fail. It’s quite common, but the test method is a no-go. You probably tested a permanent magnet Hall effect type sensor that makes its own voltage.

New coil pack solved it. Misfiring caused it to run rich and cause the pending catalytic converter code. Drives great now. I'll double check everything. Thanks.

 

[justfixedthat...]

On the ground note...not really. You have a great ground connection or not. As in that connection will be extremely tight and wouldn't allow seepage of anything to come between them. That said if your contact between them is shitty then yes it's possible. Still unlikely but anything is possible.

Perhaps the pcm as well. Add that to your possibles

New coil pack solved it. Misfiring caused it to run rich and cause the pending catalytic converter code. Drives great now. I'll double check everything. Thanks.

 

[justfixedthat...]

First explain this?
2002 Wrangler Sport
What kind of transmission is in your Wrangler? 42RLE

p.s. Have you had the alternator and battery tested?

New coil pack solved it. Misfiring caused it to run rich and cause the pending catalytic converter code. Drives great now. I'll double check everything. Thanks.

 

[justfixedthat...]

I had 3 stalls that happened when going from hard throttle to off throttle in the month leading to my fuel pump going out. It never did just buck on my though. Just lost go juice

New coil pack solved it. Misfiring caused it to run rich and cause the pending catalytic converter code. Drives great now. I'll double check everything. Thanks.

 

[justfixedthat...]

Check the easy things first that don't cost anything....

The 32 pin harness connectors for oxidation and a snug fit that are attached to the PCM. Oxidized connections can cause this problem.
The wiring harness behind the valve cover that is routed behind the head stud; there are known issues where the harness wires will rub thru causing this problem.

New coil pack solved it. Misfiring caused it to run rich and cause the pending catalytic converter code. Drives great now. I'll double check everything. Thanks.

 

[justfixedthat...]

By any chance did you happen to notice high idle or hunting rpm's when in neutral/park, or sitting at a stop light?

New coil pack solved it. Misfiring caused it to run rich and cause the pending catalytic converter code. Drives great now. I'll double check everything. Thanks.