So, I just finished my build... 01 XJ w/ 98 ZJ engine swap, aFE header, all the electronics from the '01 swapped.

It runs well, except I have a few issues with the drivetrain. I get a vibration around 3,000 RPM if I free-rev it, I can hear a ticking type of rattle coming from what seems to be the bellhousing area and the transmission slips during lock-up, which I think caused a P0740 CEL light to pop up.

The truck pulls hard with the 0630 head, header and 00-01 intake, but the grinding / vibration along with the ticking makes me concerned.

Any ideas? I'm thinking torque converter, due to the code, the rattly sound and the grinding / vibration in sync with the engine rotation... Motor only has 42K on it and is very clean inside (Popped off the oil pan and did a rear main seal).

Another note, I have a plug, located next to the distributor sensor and oil pressure sensor, with two leads, that I cannot seem to find a "friend" for. Any ideas on this? Maybe they're related?

 

I guess nobody's experienced the issue... Found a bone yard AW4 for $200.00 with a 30 day warranty, 92K miles... Any opinion on price?

 

You put all the mating bolts back to match the engine and trans and made sure it's flush?