I'm sure it's been covered, but I saw the other post outlining engine swap issues.

Recently bought 2 04' discos. 1st needed head gaskets, 2nd had a broken camshaft.

I pulled a 4.0 from a 2000 and dropped it straight in to the 04' that had a 4.6.

No issues with the engine management system, car runs great.

 

Wow, very interesting. I've read here that the opposite swap (4.0->4.6) requires a reprogram. So I'd expect the opposite to be true.

 

No codes, passed smog the next day.

 

good to hear that you got that thing rolling. too bad the 1st attempts didn't fix it. guess the po was right.....それは新しいエンジンを必要とします

 

Thanks Dusty. I'm going to rebuild the 4.6, top hat and all to have ready.

I got lucky. The 4.0 I pulled at the JY on half price day. The car had minor damage from an accident. So I ran the carfax on it and saw it had passed smog 2 weeks before going to the JY.

I paid a guy at the JY to help pull it, all together cost me just under $300, so I'm happy with it. It was a gamble as I never heard it run, but it's smooth.

 

The ECU does not need to be reset other then to trip the switch from 4.0 to 4.6 or visa versa.
As for installing a 4.o or 4.6 look for one from a P38, they were better engines.

 

Mike- what do you mean by "trip the switch"? Is this an automatic thing that happens? I didn't physically trip any switches.

Thanks for the heads up on the p38, I have been looking for a GEMS 4.6 for a while.

 

So no issues with the tranny either? Interesting. If I came across a blown 04 I would drop my 4.0 from my 2K in it in a heartbeat if this is the case.

 

Honestly, it feels like it drives better than our 04' with a 4.6. Shifts effortlessly and the ride is perfect.

I couldn't be happier.

 

4.0 to 4.6 is fine with no programming also.