Swapping XC90 Engines

Morning all,

I am about to swap an engine on a Volvo xc90 2005 model from a T6 4 speed to a 2.5T with the ECU and Ignition immobilizer to match the ECU as well as swapping the guts from the other key to the key already in use for the door handles and Ignition barrel so no issues of starting.

Can anyone else recommend any other kind of precaution or checks i will need to who has done this kind of swap before? Also note the reason i am swapping is because the engine in the car already is blown.

Thank you.



  • Ex850RSnoopy @Ex850R Somewhere Over the Rainbow. Melbourne.

    I seem to recall you would need to swap ALL the wiring and modules, the rear view mirror is a key part of the system too believe it or not!

  • What is the rear view mirror got to do with the engine starting process? Both makes are LE varients my car and the donar car. Mine is a 2005 2.9T AWD and the donar is a 2004 2.5T AWD.

  • Ex850RSnoopy @Ex850R Somewhere Over the Rainbow. Melbourne.

    It's part of the CANBUS.

    That's why you need every module and wiring from the donor.

    This is my interpretation, if you haven't researched and asked a Volvo tech you should.

  • @Batty251 you're on the wrong track. Simple advice is scrap the 2.9t XC90 and move on with your life.

    As @Ex850R mentioned, these volvos use a complicated canbus system. You can't just swap an "ecu, immobiliser and key"

    Even if you had identical cars, it wouldn't work without swapping every programmed module.

    Note that the two engines you're talking about using have different gearboxes and transfer cases.

    Brief rundown to try and talk you out if whatever you're trying to do.

    All of the electronic modules on the high speed canbus are vin programmed. This includes your dash cluster, CEM module, ABS module, ECM and probably your rear view mirror as it's the receiver for the central locking.

    The wiring looms (engine bay and body) will be vastly different between the two models.

  • So going by what I've been told by both is that nothing can be swapped or changed even if the vehicle is complete and just one modual or assessory breaks or wears out i can't even change that with a new one or used one with out the canbus saying no that's not my part and the car won't work.

    Dose that sum it up?

  • Basically yeah you can't use 2nd hand modules, they need to be brand new and they can only be programmed by a Volvo dealer

  • bgpzfm142bgpzfm142 @bgpzfm142 Launceston TAS

    From what I've read, the carconfig file won't let you add certain options or change the types of major components, which includes engines, but also some factory options like adaptive cruise control.

  • So just to check you guys have done this before to know this? Keen to know the story of how it happened and why and what the outcome was.

  • @Batty251 yes Im a mechanic that specialises in Volvo's.

    It's not like other manufacturers (Holden,Toyota,Ford,VW) where you can program modules and keys etc with the right scan tool.

  • Being a mechanic though that specialises in Volvo's you could share a story of the same situation or similar that your proposing happens if i do such a task? Like replace a engine or tranny or anything ?

  • Not sure if you're trying to argue or need more explanation?

    1998 is the cutoff for being able to swap an ecu without coding

    You're still talking about swapping a T5 engine into a T6 xc90?

    I'm not saying it's impossible, but Its clearly beyond your skillset and what happens is you realise you've wasted a shitload of time.

    I'm not sure if you've even comprehended half of the stuff I've mentioned so far and you still seem to be thinking that the electronics in this car are like a commodore

  • PaddlerEdPaddler Ed @PaddlerEd New England Region, NSW

    I think @timbo has answered the question in a bit of a roundabout way.

    "You guys have done this before to know this?"

    No, I suspect that they have not done it because the knowledge exists (quite widely) that it is not possible without moving every single coded electronic component across; this list includes all the ECU/ECMs, the Body Control System (this runs nearly every 12v circuit in the interior) and even things like the interior mirror.

    Basically, it's a beyond cost effective job.

    However, your next post is a bit different:

    Yes it is possible to replace engines and transmissions... but they are like for like.

    @timbo will be able to explain more on this.

  • I'm curious though how is there so many Volvo's with engine swaps like the popular upgrading their 2.5T to the yamaha V8 if your proposing it simply dosen't work however its been done like more then once. Especially on this forum where someone did just that for higher year then my car XC90.

    I'm not doing anything besides asking a simple question and just curious to how it dosen't work when all i get answered back is i just know it won't work.

    Have a google search for such engine swaps. It's been done.

  • No one on this forum has swapped a 2.5t to a V8, not even once.

    No-one really engine swaps xc90s

    I'm not saying it "just won't work" but your not really showing any signs of understanding what's involved with either the engine swap you first mentioned, or with the broader concept of swapping a late model Volvo engine between chassis.

    If you have a complete donor car then go for it and swap every loom and module from the donor car.

  • Ex850RSnoopy @Ex850R Somewhere Over the Rainbow. Melbourne.
    edited May 15

    If you want to unpick and swap every single electrical part of the CANBUS, from donor to your vehicle you should have success.

    Maybe someone in the world has done such a thing,it would concievably take ridiculous amount of time though.

    And has been said , and it is common knowledge it is not possible to do this swap, if you read it on the internet that it is possible then that's because "that's the internet " not because it's true.....

  • edited May 16

    None illustrate a successful engine type swap.

    I'm undecided.

    Either a very poor grasp (!) or trolling ......

  • Ex850RSnoopy @Ex850R Somewhere Over the Rainbow. Melbourne.

    Go ahead and do it.

    You are wasting a lot of time here not listening after you asked a question and got the right answer. Time you will need with kilometres of wiring to swap hahaha.

    If you have all that information then off you go. You don't need the informed answers you got here.

  • 3 of the users have a succesful project and others were more advise about how to go about it.

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