Swapping 2003 4.0 with a 1999 4.0

[MacGryphon]

I need to replace the 4.0 engine in my 2003 TJ.
A local guy has offered a remanufactured Spartan/ATK 4.0 engine from a 99 TJ, fully dressed, for $800. Has only 8k miles on it with paperwork.

1. Is this a good deal?
2. Is it even compatible with the computer in my 2003...what problems might I encounter?

 

[Chris]

It's a good deal, but it's not going to work with your 2003. The 1999 4.0 is a lot different. It doesn't have the pre-cats for instance, and a good majority of the sensors are different (as well as the ECM), so your wiring harness isn't going to work with it either.

For instance, your ECM is going to be expecting to see 4 O2 sensors. However, that 99 setup only has 2 O2 sensors, which is what it's ECM is expecting to see.

 

[MacGryphon]

That’s pretty much the answer I was expecting. Thanks, Chris!