Dies in the hottest part of the day

[tlhovey]

Bought my 2010 Ram 1500 TRX, 5.7L Hemi with 133k miles on it less than 2 weeks ago. It ran great until it didn't. It has lost power, stutters and stammers, and then dies. It will start up again, but will lose power and die like before. After letting it sit for maybe 1/2 hour, it'll start and run just fine again. A couple times we were towing a small trailer with a motorcycle on it. Then a couple other times, not towing anything, just driving. Every time it occurred in the hottest part of the day in triple digit heat. I pulled codes which indicated MAP sensor. I changed the MAP sensor, but the truck still dies on me in the heat. Any ideas? I bought it "As Is" and "No Warranty" so I'm in a pickle here.

 

[Burla]

You use the same gas everytime? Have you tried 91 octane, different from usually gas station Chevron or shell would be good? Fuel, air, and spark, generally speaking you can eliminate spark here. So high flow air filter and mess with gas strategy, even look for non ethanol gas if you can find it. Only code was for map? Use OEM replacement?

 

[tlhovey]

Yes. I have used the same gas. 86 octane. We do have a few 100% gas pumps around here. I'll give that a try. Thanks. There were actually several codes, which led our local mechanic to suspect fuel/heat related. P0171 Fuel System Lean (Bank 1); P0174 Fuel System Lean (Bank 2); P0868 Transmission Fluid Pressure Low; P0934 Line Pressure Sensor Circuit Low

 

[Ken226]

the P0171 and P0174 codes are likely unrelated to the transmission codes.

It sounds like the truck has some transmission issues, as well as the fueling issues.

The P0171 and P0174 codes indicate the same condition on both banks of cylinders. This likely eliminates things like injectors, spark plugs, etc. I would start looking for things that are allowing too much air, like vacuum leaks, loose or broking vacuum fittings, loose intake manifold bolts, or, things that are restricting the flow of fuel, such as a bad fuel pump or clogged fuel filter.

As to the transmission codes, I would start by crossing my fingers, saying a prayer, then replacing the transmission fluid pressure sensor. Hopefully, the sensor is bad and the actual line pressure is fine. Otherwise, it might start getting $$. If the transmission has been working well, shifting good, etc, then the sensor is probably bad. Actual low line pressure would likely manifest in shifting/slipping issues.

The line pressure sensor isn't hard to replace.

45RFE and 545RFE Transmission Pressure Sensor Replacement

This video explains how to replace the Transmission Fluid Pressure Sensor on Chrysler 45RFE and 545RFE Transmissions found on Dodge Dakotas, Dodge Durango an...

www.youtube.com

 

[Burla]

Those trans codes are most likely related as in they are reading something as the engine is dying. Since it's slowly dying and not shutting off right away if it was electrical, these codes can pop up. Hemi's are OEM tuned for 89, so yeah see if 91 turns you around and report back. Since it only happens when hot and those codes, I would be working on the fuel portion of the issue. Since it's a 2010, you don't have grill shutters, but the issue "might" be just too much temperature in the engine bay, maybe insulate fuel lines if you can find it.

 

[Dean2]

In addition to the very good advice above, the high heat causing issues may also indicate a bad battery that is failing when it gets really hot. If you don't know when the last time the battery was changed, I would put a brand new one in and see if that helps solve the issues.

Also, GENTLY push down on every fuse and relay in the engine fuse block and make sure they are fully seated. Loose fuses are very common and lead to many gremlins like you are seeing.

 

[Dean2]

So OP, any updates and progress?