My motor decide to take a **** and I’m in the process of swapping it out with an identical motor “99 4.0 I6”. my question is am I fine with the Ecu I have or am I going to have to program it?

 

It should be fine.

 

No you will not have to program it, plug & play...computer recognises igntion key for immobiliser and stores VIN...ur not changing either

 

What happened to the motor?

 

Yeah, how do you blow a Jeep 4.0?

My last project knocked like a cement mixer, the rod bearings were 0.020 thinner in the middle.
I've seen them so worn out and abused that after pulling the head, you can more the piston around in the bore with your fingertip.

But, I've never seen one blown.

 

A sudden loss of oil pressure does wonders! Ask me how I know.....

 

How did you lose oil pressure? Coolant in oil from cracked head?

 

No, sheared oil pump drive tangs with no apparent reason. Brand new Melling pump from Pep Boys who kindly lost all the paperwork so Melling disavowed any claims. Needless to say, I was very upset and would like to forget the whole situation. Melling has the pump and couldn't find any thing wrong with it other than the sheared drive. On rebuild I replaced the cam sensor drive unit just in case it had anything to do with it.

The motor stayed together, but the crank was toast.