Posted this on Newbie, see what hardcore forums thinks....
MY problem:

Own a 1997 TJ 4banger, AX5 - swapped in the 4.0L from 2000 Sahara along with the AX-15. Donor vehicle included engine harness and computer. Installed engine and tranny - no problem. Recently completed engine harness wiring - and all final details of installation. When it came to start- NOTHING. After adjusting all the conection on engine harness and replacing fuel pump- engine cranked! Engine roars on, and after 2-3 seconds it shuts right OFF! SAME RESULTS OVER OVER OVER OVER OVER OVER OVER.....

I can't figure it out, after reading the forums I realized everyone has issues with the swap...... I am in way to deeeep to pull out now. ANY HELP WOULD BE GREATLY APPRECIATED.


Auto Shutdown Relay didn't do anything for me, it must be sentry key system! Help me bypass!

did you replace the ECU, if the donor had a security system this will keep the engine from running without all the underdash wiring and computers. there is no way to reprogram the ECU to bypass that, the only option is to replace the ECU... and it's a stealer item, about $400

I have not tired a new ECM, I was only able to get a buddy's his Jeep was a 99 not a 2000 - 2000 model does not have distributor. How sure are u that a new ECM will work? I looking for deal on the web, I would hate to spend big bucks on one and it not work @ all. Anybody else ever live thru this?

Yup.. my guess is your buddies has the sentry key BS, causing the jeep to shut it self off.
Scott

Find a used PCM from a junkyard from a 2000 TJ either an X or Sport without SKIM.

Have the junkyard give you the VIN then call the dealership to see if it had SKIM from the factory.

I had the same problem when I did my first 4.0 swap. Picked up a used PCM for $75.00 from my local salvage yard.

fairly sure the ECU is your issue, had the same issue when I did my swap, would start run for couple seconds and shut down, ECU was my issue... careful with the junkyard ECU's, once the security feature is on it can NOT be turned off, most junkyards wont take electrical parts back. I was never able to resolve all the trouble codes and ended up changing electrical and injection system to the ODBI.

good luck

Well, I found an ECM from a 2000 SPORT and so far so GOOD! Mechanic is finishing her up as we speak. I'll post before and after pics soon as it's wrapped up! (ofcourse only if not hitting any more obstacles for this project) Thanks Jeepers for all you help!!!!! it took some time but I finally found the ECM for less than $100 and guaranteed to work, cant wait to see how that 4.0L will compare to 2.5L it use to run!

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