Engine swap cutting out

[Stranded101]

I bought a 97 Wrangler Sahara that had lost compression in the original engine. I purchased an engine off a 96 Cherokee that fits with low mileage and did some TLC (gaskets etc.) then threw it in the Sahara. After all of this, I went to crank it and long story short the engine will turn over and run for 3 seconds. I did a test with starter fluid and she runs well but once you stop spraying it cuts off. Here's a list of all the things I've done to try to solve it and honestly I'm stuck on where to go next. Any help would be greatly appreciated.

Replaced or worked on:
- Starter
- Fuel Pump (tested pressure and is getting 40-50PSI)
- Fuel Injectors
- Crankshaft positioning sensor
- Tried both distributors from the previous and new engine
- Tried both throttle bodies from both engines
- ASD Relay
- Cleaned and checked all grounds
- NOID light test (all 6 good)
- Alternator test checked out good
- New battery

Honestly, the only thing I keep seeing is a security system within the key, but the key the Jeep came with was a metal plain one and a black simple plastic one. Don't think there is a security system in this jeep.

 

[dvngdg]

runs for 3 seconds, SKIM, Maybe ?

 

[Moglocker]

runs for 3 seconds, SKIM, Maybe ?

Only thing it could be,maybe the Cherokee had skim,and something was left installed on the donor engine?

 

[macleanflood]

@Wranglerfix www.wranglerfix.com can delete the SKIM off your PCM.

-Mac

 

[Bammo68]

Replaced or worked on:

- Tried both distributors from the previous and new engine

Sounds like you have already done this but one of the things that caught me off-guard was how easy it was to stuff up the initial timing by installing the distributor out of synch. If you follow some of the YouTube instructions you wind up with something like 30 degrees advanced timing. What surprised me was that the engine would start easily but then got rough and stalled shortly afterwards.

Might not be your issue from the sound of it but just know that setting the initial timing synch is critical and a lot of the instructions online how to do this are wrong - make sure you follow the FSM instructions.

 

[CharlesHS]

Did you reuse any of the '96 XJ sensors or did you reinstall the '97 TJ sensors ?
If the amber circle w/ slash and key illuminates after 3 seconds; that is a tell tale sign of the SKIM system activating which shuts down the engine.
Assuming you did not swap the '96 XJ ECU into your '97 TJ and did not touch the Immobilizer module (passenger side of steering column); I would reverify all sensor connections and inspect the 32 pin harness connectors attached to the ECU for oxidation and other connection problems.
I would also inspect the ECU wiring harness that runs along the firewall and is routed around a threaded head stud in the right rear corner of the head. This stud is known to rub thru the split wire loom and wiring insulation causing electrical shorts to ground which will interrupt the communications between the sensors and ECU.
IF all of these checks do not provide a solution; then as contact Mark @Wranglerfix as MAC suggests.

 

[Wranglerfix]

@Stranded101 An irregular spike in voltage can enable the skim function in the ecm without having skim. I can disable with same day turnaround time. I apologize for the delay in getting back to you.