So I have four 1998 xj8/xk8s in the shop. I was planning on doing an engine swap between two that have a build date two months apart (motor from early 98 xj8 into a late 98 xk8)and the engine elctronics are totally different. ECU, VVT, and knock sensors are the ones I noticed right away. Is this normal in 98 or has someone been in here before and swapped stuff around?

Has anyone converted the early 98 xj setup to the late? Can I just switch the sensors and controls to the late setup and leave the harness in the late car? I am guessing that I will at the very least have to swap some valve covers as well.

 

sounds like AJ26 to AJ27.....not easy, are the throttle bodies the same? are the module connectors are different? Can you not lift out the XJ unit with everything intact and install?

 

You are correct, the TBs are different too.

Both cars are complete and I can take everything outta either car, the xk8 has a seized motor and it is the customer car. The xj8 is a totaled parts car I bought from a tow lot.

We are a Porsche shop, I really outta stick to Pcars :-)

Thanks for the nomenclature, I might be able to turn something up on a search instead of bugging you guys 15 times in the course of this project.

 

Feel free to bug us with all the questions you want! We enjoy solving problems.

A short block swap is the easy answer.

 

HAve you found this yet?
Quick Reference: Swap your 4.0 block with a 4.2 - Jaguar Forums - Jaguar Enthusiasts Forum
Keep us posted on the results.

 

You might also do a search on my RANT about a customer that put a 1999 engine in a 1998 XJ8 and did NOT swap the torque converter drive plate that has the crank sensor reluctor segments that are different from AJ26 to AJ27. He swapped everything including the intake manifold, intake cams, front covers, the engine harness etc. but the 'flywheels' are completely different!!!!!!!!!!!!

It was a long time ago but I still remember the CMPS/CKPS relationship faults that drove me crazy for 2 days.

bob gauff

 

bob,
How in the world did you find it?

 

The customer brought the car in to the Dealer I worked at because the engine would not run right. It sputtered and idled rough, would not rev much and had DTC for CMPS/CKPS relationship fault. I tried to pin-out the harnesses and replaced components. I looked at the 'B'bank cam to be sure the reluctor had not fallen off the intake cam..

I finally talked to the customer when he came in and sat down in the service office for an update. He said that when he and his son finally got all the components swapped from the 1998 AJ26 engine to the 1999 AJ27 engine they were happy everything fit and it started and ran but was misfiring and running rough.

I could not believe what he just told me and I asked him "you did what????"

I went over to the car and saw the CMPS in the 'A'bank head that was not connected, just there to plug the hole.

I then asked if he swapped the Torque Converter Drive Plate and he said 'No, Why would you need to do that?"

Then I looked at him and said "FOUND THE PROBLEM"

The drive plates have different slots in different locations as well as a different number of segments.

I asked if he could bring the plate to me and he said it was up in Oklahoma at his son's place. He finally got it to me and I installed it. The engine ran normally and he drove away after paying his bill.

I did know that the engine was replaced and then it ran rough but I did not know he used a later engine.

bob gauff

 

Good advice!

 

I think I am going to either take testpoints advice and short block the xj8, or go find a late motor for it. Moving backwards to an early setup seems like the wrong thing to do to the guys car.

but thanks for the post, I don't know if I would have seen the differences in these plates.