hello everyone, has anybody done this? i have a 3.0 car that may have headgasket prooblems, i know that it may be better just to swap the engine, so my question is can i install a 2.5 instead of a 3.0, what else do i have to install to make it work propperly? thanks in advance for your help

 

nahum, mounting wise, the 2 blocks are identical and getting it into the car is not a problem. The big issue that you may have is the fact that the computer is tuned for one size engine and you have another. Now, with that being said, you can get a new ECU and that will fix this issue. But, this leads to the fact that it will force you to end up at the dealership to have them program the ECU to the car since the ECU and the PATS module (security system) communicate when starting the car and if they don't have the correct hand shakes when the key is in the START position, it will prevent the car from starting.

 

Nahum, also the difference between a 2.5 and a 3.0 is like a bicycle and a motorcycle. I've had both. 2.5 is too under-powered for me. Jack

 

thanks again thermo, as usual you are very prompt with your responses, would it help if i have the same ECU from the 2.5 engine? do istill have to take the ECU to the dealer to get it flashed or something?

 

thanks for your reply pophen, i happen to have 2 x-types at home, my daugther (3.0) and my wifes (2.5) you are right as far as the power difference, although the gas saving is also very obvious, I think my daugther will preffer the gas economy over the power , I think

 

nahum, like I mentioned, you are pretty much forced to take it to Jaguar to get the ECU reprogrammed to accept your current keys. When you start the car, there is information that gets exchanged between the PATS module (security module) and the ECU. Part of this information is a number that is unique to the key you have. If all the numbers do not match up, then the signal to the starter is not outputted.

 

can i take the ECU by it self to the dealer to get it reprogrammed? or does it have to be installed? thanks again Thermo

 

here is an update on the issue.
I did replace the 3.0 engine with a 2.5 engine I used the same ECU from the 3.0 as well as the throttle body and intake manifold. the car started right away and I have not had any problems as far as any check engine light or misfiring, of course there was the initial troubles involved with replacing engines, like bad connections or adjusting the transmission cable, but other than that the car is working properly. I still have to change spark plugs, valve cover gaskets, oil, filter etc.. I didn't do any of that because I wanted to make sure that the 2.5 engine was going to work at all.
I will let you know if any issues happen after driving the car for a week.
once again thanks to the members that collaborated with their input, specially to thermo.

 

I tried posting an update today and it didn't work, so here I go again.
I test drove the car for 150 miles today, the car work normally with the exception of power been slightly different, obviously the car has a little less power now with the 2.5 engine instead of the 3.0, although like I've said before the gas mileage was better, it took exactly 6 gallons of gas to drive the 150 miles, I don't know if the mileage will improve after I replace oil, spark plugs and filters. but even if it doesn't 25 mpg it pretty good in my opinion vs the 23 mpg we were getting with the 3.0.
the car shifts normally and everything else seems to be working ok, I will repost an update in a week

 

will the ecu from a 3.0 xtype car work on a 2.5 xtype.....the ECU on my 2.5 is the suspect of a malfuntion (transmission in limp-mode)

 

You'll need to have it flashed anyway, for the security functions, but the 3.0 program will happily run the 2.5 with no issues; going the other way, the 2.5 ecm will also run the 3.0, but not to full potential.