I have searched and searched the forum and can't seem to find an answer to this one.

I have a 1996 XJ, 4.0L AX-15, NP231. I broke my back in January and couldn't drive, so my Jeep sat on the driveway until April. Before I broke my back, I wasn't driving it much at all because it felt like my transmission was slipping or at least there was some hesitation and I didn't have the money for a new transmission, so I just started driving one of our other cars around for the time.

After I got better, I started driving my Jeep again, and at first it drove fine. After a couple of weeks, it started dying when I took it out of gear while stopping at a stop light. Then the slipping or hesitation problem started in again.

I have 294,000 on the odometer.

I hooked up my OBD II scanner, which also does Mode $06. I had a mode $06 code come back that pointed to the TPS. I changed the TPS out with a brand new one, which didn't fix the problem. I started inspecting the vacumn system and found a hole in the line between my PCV valve and my airbox. I replaced my PCV valve, popped the valve cover off, cleaned it all up, cleaned out the lines, fixed the small hole in the vacumn line, cleaned out the rear fixed orifice and put a new valve cover gasket (Fel-Pro rubber metal type) along with some RTV sealant. To no avail. My problem still exists.

Miscellanea: my after cat O2 sensor has been disconnected for about a year and a half. I've never experienced any problems from this, all it did was trip a CEL.

The PO somehow lost two engine to bellhousing bolts. I believe that that could cause the transmission to slip. I'm also missing a mounting bolt for the CKP. It holds fine, but it may be an issue. I don't know.

I was thinking about disconnecting the forward O2 sensor to try to isolate the problem. If that fixed it, I would know what the problem is and could replace my O2 sensors. Any other thoughts on what I should do? I'm running out of ideas here. Thanks, in advance, for your time and consideration.

 

Since you know about the issue with your O2 sensors and transmission bolts, replace them and go from there.

 

I had planned on it, but I was searching for any other knowledge as to what else it could be. I did a fluid change on my AX15, as well, but forgot to mention it. I was running Royal Purple 75w90, which is GL4/5 rated and now I'm running Amsoil 75w90 which is straight GL5. I have it in the back of my head that the Royal Purple started eating the synchros in the 18 months and 20,000 miles that I had it in. Maybe not, but I'll probably never trust it in an AX15 again. Amsoil is GL5. I know that works because Chrysler tells me that it does.

 

Update:

Transmission to Engine bolts are all in place and tightened. That hasn't solved the issue. Also, tried unplugging the O2 sensor and that didn't solve any problems, either.

Anyone have any ideas? Please?

 

I'm a bit unclear as to whether it's your transmission slipping or the engine is hesitating, or perhaps both?.

I did catch that it dies when you take it out of gear. Does it stay running if you give it some gas? If so- check over your IAC. Possibly sticking, gummed up or non functional.
Also check for vacuum leaks. They could cause hesitation, bucking, dying out at idle..

How old are the plugs/cap/rotor/wires? Any sign of deterioration?

 

I believe the transmission is slipping. The engine is also hesitating and dying at idle, although it will stay running if I give it some gas. I cleaned my IAC, and also tried swapping it out for another IAC that I had lying around in my garage.

Plugs are from PO. Perhaps I should check those. Same with wires. Cap, rotor, ignition coil are all about two years old. Perhaps I should also check my injectors, but I would need to build an injector tester first. I'm not quite sure how to go about that.