Specimen is a 1995 xj with the H.O. i6.

Problem is its experiencing random intermittent stalls, sometimes while driving and sometimes while idling, but usually fires right back up. Once or twice it had trouble restarting after a stall but after 5-10minutes would start. All dash gauges are at normal positions and fluid levels are good.

When running a Fuel PSI test my idle is at ~30psi, then rises ~+4psi when I remove vacuum to pressure regulator. The weird thing was when I cut the engine off for a leakdown test my PSI starting quickly rising and leveled off at ~40psi.

Things I have replaced recently
-Changed catalytic converter from standard 49state to Flowmaster California cat.
-Plugs, wires, cap, rotor & coil
-CPS sensor
-IAC motor
-TPS sensor
-MAP sensor
-CCV elbows
-Radiator

Trying to get this o2 sensor out now but its proving difficult. Thank you in advance for any ideas you have.

 

Looks to have been a bad connection at the ignition coil contacts, no stalls for now. Never underestimate the basics.

I'm still a little confused by the rising PSI during the leakdown test and the idle seems like it could be just a little smoother, so I plan to replace the fuel pressure regulator soon for good measure.

O2 sensor was completely seized in place, friendly independent neighborhood muffler shop threw a torch on it for me but it still required heroic amounts of elbow grease.

 

Probably not worth worrying about. No vacuum to the regulator the pressure will rise, fuel pump might run a fraction of a second after the injectors shut down.

 

On my 90 I can chop the wires to get a 7/8 box wrench on it......

Sounds like maybe a cheap, aftermarket CPS? "stalling and random dieing" ...Idk.

I think that pressure is to low for a 95> http://www.jeep4.0performance.4mg.com/tech_specs.html OK was 96 it went up, still 31 to 39 is your range I think. If that is correct, 34 is a little low.


The auto parts store might read your codes free, or try;

The "Key Tricks"
Older (OBDI) models - Start with the ignition off. Within five seconds, switch the key on, off, on, off, on. ("On" is NOT "Start" and "Off" is NOT "Lock"). The "check engine" light will flash. Count the flashes. Each code is a two digit code, so a (for example) 23 would be FLASH FLASH (pause) FLASH FLASH FLASH (long pause). It will never flash more than 9 times, so watch for those pauses!