I was wondering if it's possible to convert my 99 XJR (which is an AJ26) to a AJ27 (2000-03). I know if you just swap the ecu and tcu then they won't communicate with the rest of the car. What needs to be done to make it work?

Let's say I get an entire AJ27 parts car to swap parts from. If I swap all the modules that are listed on the VCATS sticker in the trunk, would that work? Would all of those need to be swapped or some of them? Would the modules physically connect or are some of them different? Any other mechanical differences other than the throttle body?

This is for a supercharged car, so there's no variable valve timing stuff to deal with.

 

I looked into this recently, the cruise control is different between the two, and the AJ27 has 4 O2 sensors, but if you just use the engine and ancillaries it might work. This would mean using the AJ26 cats (2 O2 sensor), throttle body (inc cruise) I'd not look into swapping all modules, the looms and connectors are different, for instance the speedo.

If your talking a complete parts car, it's effectively what I did, and that's a complete installation of the electrical system, from the reverse parking sensors to the front fog lights and all systems in between, a lot of work. This is after you've basically taken two cars apart. Again speaking hypothetically, it would make more sense to use your car to rectify the later model.

 

I don't need cruise control. My AJ26 has 4 O2 sensors as well, and I don't have cats anymore. I don't need a new engine. The whole point of doing this would be only to get rid of the monstrous AJ26 throttle body. I want to use a larger diameter but smaller overall size aftermarket throttle body, which the AJ27 is apparently able to do, and also rotate it sideways.

It would probably be easier to sell my car and get a newer year but my car is in perfect mechanical and cosmetic shape with low miles and I'd rather not trade it.

 

On that basis it would be easier to swap the engine to one with the TB you desire fitted. Maybe not a Jag engine either, there are members on here who have dropped various motors into the X308. I've seen one recently where a Chevy V8 was dropped in.

 

Except that my AJ26 ecu won't work with a different TB. I haven't seen 'various' motors, only a couple Chevy V8's, and I don't recall them being finished without any electrical issues. Also, I have mixed feelings about swapping my mint and far superior engine with a crap Chevy engine .

 

How can you put a completely alien engine in a car these days, and have it be street legal? How do you even get the electronic controls to talk to it?

 

I can be done with a little witchcraft engineering. I'm no expert on the matter but I know of a couple of companies round here that offer such a service. I have seen a 1998 XJ8 Sport fitted with a Diesel engine of some sort and recently a 2000 Range Rover with a diesel motor from a light Mazda truck.

Nothing worth having comes easy, but good things come to those who wait

 

Any techs out there know if this is a possibility?

 

Unless one has a lot of time and money available, I would think it would be a lot easier just to find the newer car. Seem to be a reasonable supply out there, at attractive prices. One could even swap the complete interior over, if the new car wasn't so nice inside. Maybe not so much fun, but a lot easier. Just my $0.02 !!

 

In a word, no, not to my knowledge. The later fly by wire TB and ECU will not work on the earlier CAN BUS. Now if you could find an electronics wizard who could make a signal adapter box to convert tps mechanical to tps electronic, you're on the way, but this would be a long and winding R&D exercise.
Why, are you planning on adding a twinscrew?

 

You guys think it's too hard, too expensive and probably not possible. That well may be. I just need someone that knows for sure to tell me definitively that it's not as simple as swapping all the necessary modules. If the wiring loom and connectors are indeed different, then I guess it won't work.


I thought the CAN BUS system was first used on the 4.2's and not earlier?



Maybe.

 

You don't like my answer, why not compare wiring diagrams, module connectors and pin locations on each module the way I did to confirm it? I've uploaded a Jaguar electrical document for you

jxj1999en.pdf

By the way 'CAN Bus is a multiplexed wiring system used to connect intelligent devices such as Electronic Control Units (ECU's) onto vehicles, allowing data to be transferred in a low-cost and reliable manner'.
If it's got modules, and they talk to each other, it's on a can bus.

If you still doubt that I have not looked into this, see the picture of a AJ26 XJR I was going to use as an electronic donor, after looking at a few modules, it was sold and I bought a 01'.....IT WILL NOT WORK ON YOUR CAR. END OF. I'm done here.

 

Ok good, so a definitive no. That's what I needed to hear.

 

'CAN Bus is a multiplexed wiring system used to connect intelligent devices such as Electronic Control Units (ECU's) onto vehicles, allowing data to be transferred in a low-cost and reliable manner'

Well, most of the time !!

 

With enough time and money almost nothing is impossible. The problem starts when you you have to ask if it is possible. If you know how something works then you can find ways around problems. If you don't understand the problem but you have enough money to contract someone who does then you are OK. If you lack the skills and have no money then you ask if anyone wants to help you for free. If all of that fails you can buy something that some has already done and has grown tired of and wants to move on to the next challenge.

Life is full of opportunities and challenges. You have to decide. Sometime I like a challenge but mostly I wait for opportunities........

bob gauff