gdcpony

So I have been chasing issues from afar on my teenage daughter's Jeep. Now I am back in town and have a more solid explanation of the current issue(s). Please bare with me as I lay this out for you guys. I am desperate here.

Replaced in the 6 months we have had the jeep:
coil pack (twice just in case)
plugs/boots (again twice)
cam pos sensor
crank pos sensor
all injectors
trans fluid/filter
front and rear diff fluids
air filter
coolant/thermostat
oil/filter

I do a full run through of every vehicle I buy just to give it a fresh start so most of that was just that. You can tell which ones were to solve the issues.

Current status:
spark on all cylinders
fuel pressure good and holds
injectors get signal
no overheats
voltage good on alt and bat

I was getting misfire codes and stalling. Now, the codes are rich on banks 1 and 2 (p0172/p0175) after my latest test drive. It stalled when throttled past 50% TPS (as read by my bluetooth reader's live data) at operating temp. after sitting 10 min it started again, but only in neutral. On the way back it stalled again as I gave it more than usual throttle. I could accelerate lightly to 70mph though as long as I wasn't on the gas hard. It then stalled as I stopped at a stop sign and immediately restarted in park and again 1 mile later which I did a neutral restart on the fly.

All times the key had to go back to all off before it would start at the very least. Also I would lose the ability to track live data on my scanner (OBD2) until I shut the jeep off again and turned it back on.

I could force misfire codes only in park once I got back by going above 4k rpm (P300, P301, P306). I have a vacuum leak (small) that may account for that portion though. I doubt that is causing all this.

We have a new ECM ready and the wife is going to schedule a dealer visit to get it "paired" to the Jeep. Unless you tell me otherwise, this is the next step.

After that, a running start at a tree seems like a good idea for it. I really wanted to like this jeep. My daughter who loved it is starting to hate it. we just can't figure it out and having it die on her on a highway full of cars isn't confidence inspiring. Please, help me out! Thanks

ihscouts

Check the fuel pump connector/connection for corrosion. Take it apart and look at the pins and sockets. I just went through this and was about to lead lube the shotgun into it. If you replace the fuel pump absolutely check, probably still damp.

4.3L XJ

You have done everything except your O2 sensors. Your code is the clue. Running rich. I bet your fuel milage really sucks too. If you replace those sensors, you should be good to go

gdcpony

The fuel pressure holds steady at 60PSI KOEO and after when turned off for 5 min. At 10min it is at 55psi. While running it is 60-62psi.

The rich capture data says it was during deceleration, almost like the fuel wasnt cut quick enough. I have since tried 2 other PCM's tested and programmed to our VIN by a member of another forum. No change. it just shuts off. not even like a stall, the engine just shuts down clean. no struggle to try and run, no precursor, just gone. I am going nuts on this thing.

Waterluvr

Question:

When the engine suddenly shuts down without warning (and you may or may not have noticed this) by chance does the sentry key light turn on in the dash cluster while the key is still in the on position before being turned off?

On the WJ's (top right of dash cluster) that's the orange circled key symbol with line through it that illuminates when you crank the engine and goes out when the SKIM module gets recognition of the key frequency and SKIM code in the PCM.

If you haven't looked for that no big deal, you really wouldn't know to or have cause to notice it as it's common for the eyes to see it when the ignition is first keyed on prior to cranking and starting but definitely keep an eye out for that next time it happens.

If it is illuminating when the engine is shutting itself off that's a red flag we haven't talked about yet, rare one at that. As you know I see lots of bad pcm's these days I reprogram replacements for but malfunctions of the skim module are pretty rare.

If we can identify a failure point in that SKIM module you can send me back one of those spare pcm's and I have some good tested SKIM modules/ignition lock cylinder/sentry key combos here that I could program the SKIM code into the pcm and send that right back to try.