2005 TJ 4.0 stalls once engine warms up

Marcus999

Marcus999

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Joined
Sep 24, 2018
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14
Location
Roanoke, VA, 24015
My 2005 Wrangler 4.0 with 6 speed manual trans has started stalling out. The engine simply loses power. I've found it stalks once the engine has warmed up and I've had to wait about 20-30 minutes before it will restart. I found, by accident, that if I unplug the throttle position sensor and reinstall it, the engine will start up immediately. Once it restarted I can go for a couple hundred yards to a couple of miles before it stalls again. I thought the TPS was the problem, so I replaced it. But, that did not fix my problem.

The check engine light has been on for a short while due to O2 sensors. I don't yet know if it's related but, when I tried to pull codes, it tells me there is no communication from the ECM.

I'm very hesitant to think my Wrangler is the only one to have this issue. Can anyone give me any ideas what is wrong. I haven't had much time to check things out so, if anyone can give me the benefit of their knowledge I would be grateful.
 
Hopefully you replaced the TPS with an OE Mopar sensor, otherwise that could be the problem (these TJs rarely work with anything other than OE Mopar sensors).

So you're saying though that if you try to scan it with an OBDII scanner, it won't connect? If so, that seems to point to a potentially larger problem... like possibly an issue with the PCM itself.

It might be a good starting point to disconnect the battery for 10 minutes to let the PCM and everything reset itself, then see if the issues come back when you reconnect it. Also, see at that point if you can connect with the OBDII scanner.
 
The new TPS I installed was an aftermarket BWD, OE style sensor.

When I try to pull codes, the SRS and ABS comes up NO CODES but, the scanner says NO RESPONSE, from the ECM. I'm worried the stalling and no ECM communication are related, meaning I'll have to replace the ECM. I hope it's not that. ECUs are about $800 plus whatever it'll cost to have it flashed.
 
An engine that only has problems once it has warmed makes me immediately think bad O2 sensor. The computer only uses the O2 sensors to set the air-fuel mixture after the engine gets close to being warmed up. The computer uses a hardwired program to set the air-fuel mixture when the engine is cold.

That also ties in with the O2 sensor related trouble codes.

If you replace them make sure you only use NTK brand sensors, avoid Bosch which don't work well for long in a Jeep.
 
Jerry, thanks for the response. I've never heard of O2 sensors causing a problem such as this. I mean, you can disconnect, and if someone is stupid enough to eliminate, the O2 sensors and the engine will still run fine. Though with worse fuel mileage. O2 sensors help the computer calculate for fuel/air ratio, but that's about it. I fail to see how they could cause the engine to simply lose (electric) power and stall.
 
I don't know if this is similar but my TJ is cutting out sporatically too.

I've use a OBD2 wireless tranmitter and use the Dash command app on my iphone to read the issues. It's not throwing codes mostly but is throwing errors - which are Oxygen sensor heat - Oxygen Sensor - Catalyst Monitoring. Recently it did throw a code which was bank 2, sensor 1 slow to respond. When it comes good only the Oxygen sensor heat is in error.

I've got a set of NGK 02 Sensors ready to put in and have ordered a new exhaust section with the 3 catalytic converters. Funny thing is, when it's cold weather it's really bad, in hot weather there isn't any issue.
 
From some research I've done, I've found that the crankshaft position sensor are notorious about going out in the 4.0L engines. So, I picked one up and installed it. I work at a parts house, so with my employee discount it was about $14. I drove for 13 miles, the longest I've been able to drive continuously since this mess started, without a stall. When I pulled over to turn around it happened. I didn't make it back home before the battery died from all the restarts. In less than 9 miles it must have stalled 20 times. Sometimes i could get almost a mile before a stall. Other times I would have to reset as many as 4 times before I could move. Damn, this is aggravating. I have some writing and power readings to make tomorrow, but I'm still scared it's going to turn out to be a fried ECM.
 
I had this recently myself on an 06 Rubi Unlimited, for me it was the cam position sensor and no issues since replacing that. I did replace the crank position sensor first, but still had the stalls.

You can see my post here.
 
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It's not a major change, but I did learn one thing, thanks to many of the posts I've read here, on the forum. I was getting out of my Jeep, popping the hood, unplugging and re-plugging the throttle position sensor to get it started again. I did realize for it to restart I also had to turn the key off. I wasn't always doing that. Oops! When it stalled I only removed the key and tried it again. It started, but it still stalled, of course. At least knowing that saves me a lot of unnecessary aggravation. Thanks to everyone on the forum. Please keep sending the ideas. Something will eventually pan out.... once this damn rain stops so I can get out to work on this beast again.
 
Marcus999 said:
It's not a major change, but I did learn one thing, thanks to many of the posts I've read here, on the forum. I was getting out of my Jeep, popping the hood, unplugging and re-plugging the throttle position sensor to get it started again. I did realize for it to restart I also had to turn the key off. I wasn't always doing that. Oops! When it stalled I only removed the key and tried it again. It started, but it still stalled, of course. At least knowing that saves me a lot of unnecessary aggravation. Thanks to everyone on the forum. Please keep sending the ideas. Something will eventually pan out.... once this damn rain stops so I can get out to work on this beast again.
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When you are starting in this case, does it turn over but not catch? Mine was similar and I had to fully remove the key from the ignition before trying to start again - which it would right away. From what I understand this lets the sensors return to their default state (in the case of a faulty sensor). Mine seemed like it would stall out when the live sensor data was being fed into the system, typically heat exacerbated this until the sensor went bad fully and would happen more regularly.
 
The startling starts once the engine reaches normal operating temp. I have to turn off the ignition switch and remove it before attempting to start again. It will usually take an extra couple of revolutions of cranking before the engine will start. Occasionally the engine will immediately stall again and I'll have to start over. After a few restarts, the stalling happens more frequently, every 10-20 seconds, with a seldom period when I can go 2-2 1/2 minutes before it stalls again. So, great definitely exacerbates the situation.
 
I have a 05 Wrangler Unlimited automatic that would just lose power and die. Brought it to three shops including a Jeep dealership. All after using scanners pointed to the PCM. Their scanners picked up that my transmission temp was over 600 degrees. So the transmission control module (incorporated into the PCM 05-06) told the PCM that the temp was too high and the PCM shut it down. The dealership just told me they couldnt fix it with out a rebuilt, refurbished PCM and the dealership wait was at the time 3 months. Trying other avenues to get mine rebuilt. If this company can get me a stable PCM these Jeep forums will be the first to know.
 
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Here's the latest Jeep fans. I've done more research which led me to replacing the camshaft position sensor (CPS) and I've had an odd result. The stalling has improved, but not gone away. Right after replacing the CPS I took the Jeep out for a test drive. I got about 5-6 miles before it stalled. Then, I continued driving another 20 miles without a stall. Before it would stall again, I could go anywhere between 20 feet and a mile. Now, it could be anywhere between a mile and who knows where until the next stall. Also, since replacing the CPS, the CEL has popped a few times. Mostly O2 sensor codes - all 4 at once. That tells me it's not actually an issue with the O2 sensors, but something else. Otherwise, it wouldn't be all 4 senators at once, every time. You may have noticed i said "mostly" O2 codes. One time it wasn't O2 sensor codes at all, but only one code - the crankshaft position sensor (CKP). I replace the CKP 1 or 2 days after this problem started, but with an aftermarket, BWD sensor. Since replacing the CKP that code has popped only 1 time. So I'm not completely convinced it's the problem. I've checked for codes with a scanner and the 3 key cycle trick and the codes I've just mentioned are the only ones to pop and when checking with a scanner the ECM comes back as "not responding." This has been consistent from the beginning. Before the stalling problem started, the CEL was on for a short while, but only for O2 sensors and the ECM never failed to respond. Therefore, the possibility of the ECM being the primary source of the entire problem has never left my mind, but it's starting to look like it IS the problem. Since the CKP did pop a code since being replaced with an aftermarket sensor, I'm considering replacing it again with a MOPAR sensor. If the problem persists, I think that leaves me with no other alternatives than the ECM. If anyone has any other ideas I would be appreciative and happy to entertain them.
 
After replacing the camshaft position sensor (CPS) and the crankshaft position sensor (CKS), both MOPAR sensors, I went about 2 1/2 days before the engine stalled again. So, I stopped by my local Chrysler dealer and spoke with a friend about what's happening. I've gotten a new code for the Idle Air Control (IAC) valve, but that's not important. There isn't anything wrong with the IAC. As soon as I told him all 4 O2 sensor codes popped when the engine stalls he told me the ECU is the problem. Not great news, but it was what I was expecting. He did give me some good news. I don't have to get a new computer. It only has to be from another 4.0L with a standard transmission and WITHOUT a transponder (chipped) key. That does mean I have to be careful to make sure I get a very specific ECU. Otherwise, i won't be able to turn the CEL off. Of course I will check my local salvage yards, but I'm sure I'll have to go online to find one specific to my needs. If anyone possibly has an ECU that fits my needs, let me know and we can talk about a price. $$$$$$
 
Marcus999 said:
That does mean I have to be careful to make sure I get a very specific ECU. Otherwise, i won't be able to turn the CEL off. Of course I will check my local salvage yards, but I'm sure I'll have to go online to find one specific to my needs. If anyone possibly has an ECU that fits my needs, let me know and we can talk about a price. $$$$$$
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What did you finally do? I have some of the same codes but no stalling yet.
 
I have a friend who works at my local Chrysler dealership. A great tech. As I was going through the details of what was happening I mentioned that all 4 O2 sensor codes would pop when it would stall out, but I discounted them, of course. The engine stalled, but the ignition was on and the engine was still turning because it's a standard shift. He stopped me in mid sentence and told me the problem is the ECU. All 4 O2 sensor codes popping at the same time is the give away. 2 days later a nice cold front moved in and suddenly the stalling stopped. My problem wasn't fixed, just the cooler air kept the engine compartment and the ECU cooler, which prevented it from overheating and causing the stalling. That bought me some time to continue driving my Jeep until a bit more confident time when I could afford to be without my primary ride. I hope this helps.
 
When it comes to buying new sensors for any Jeep 4.0L, NEVER by aftermarket. Spend the extra money and buy OEM. If you want to start with aftermarket, just save yourself the aggravation of finding out the hard way. Just send that money to me. Then you can spend more money to get the OEM parts to fix it properly. I found out the hard way and later had my friend at the dealership tell me that. Learn from my mistake. By OEM sensors from the start. Good luck.
 
I know it's been quite a while since I've posted anything here. It's because I haven't had anything new related to my Jeep and my issues for quite a while. But I have something new now that I'm hoping will help many of you from the Jeep Nation.
The stalling issues stopped for the cool months here in virginia, but picked up where it left off one the weather got warmer. I did a lot of searching online and found a site the repairs and sells remanufactured ECUs. At first I was very skeptical because the purchase was through eBay and the price was excellent. It's through a company called "Your Parts Solutions".
I first made a purchase from parts geek, but they didn't have what I needed and refunded my money. After a bit more research, I decided to give Your Parts Solutions a try. After an initial exchange of emails, I decided to call them and discuss it to make sure they had what I needed before I made the purchase. The jackals I spoke with confirmed they had what I needed, but tried to up the price on me by almost double. He claimed the ECU I needed was rare and that was the reason for the price hike. When I asked if he would attempt to get closer to the price advertised on his company's web site, Your Parts Solution. He said, "No." I promptly hung up the phone without any further discussion.
I decided to immediately make the purchase online, from the there. If the part that came was wrong, then I'd return it for a refund. If I received a refund and an email stating that the purchase was invalid due to a price issue, meaning that they wouldn't sell it to me at the price advertised online, then I intended to cause them a lot of trouble through eBay.
The part arrived a few days before the confirmation email said it would arrive.
I disconnected the battery, installed the remained ECU and took it out for a long test drive. No stalling. So, it appears my Jeep is fixed.
If I have any trouble with the ECU in the next couple of months I'll be sure to let everyone know.
People are quick to spread the word of their bad experiences with a company and I did not appreciate the jackass I spike with telling me the price was almost double what was advertised on their web site. I am grateful for the quick online responses I received, on Sundays of all times, when I had questions. Also, I feel I've purchased a quality product, at least for the moment, at a great price from "Your Parts Source. "
 
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Hey Marcus,

Thanks for posting and continuing with the updates. I have been having the exact same problem with my '05 4.0l standard TJ Sport. The issue went away once it got cool and has returned with a vengeance in the past few weeks. I haven't yet done any work on the jeep myself, but do have a mechanic that I trust - albeit not a Jeep specialist - who has put many hours and miles into my car trying to diagnose (free of charge). I'm wondering if it's best to circumvent the replacing of sensors and have them do the ECU. I'd love to hear how you're still doing with the one that you've put in. This is my primary vehicle and it's not an option for me to losing power on city roads.
 
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