swapping a 3.9 to 4.6 computer

[madrangie]

hey guys i have a 94 series 1 disco 3.9 i was thinking of upgrading to a 4.6, I was wondering if a 4.6 computer will connect straight onto the existing wiring loom or will i have to change the engine loom as well ?

Cheers Joe

[armbrup]

Ha HA HA LOL !!!!
I think I might get a stitch.
No its not possible.
The 4.6 either GEMS or Thor have much more sophisticated computers than 3.9 and both ECUs as well as having integrated Body functions, have security features that are designed to not let an ECU from one VIN run in another VIN. My understanding is that the only way to use a Thor motronic in another model is to buy a NEW one with all security and body functions disabled.

In addition a 4.6 has crank position sensor, cam position sensor, no dizzy,knock sensors, O2 sensors, transmission control ,and so on.

However a 4.6 will run on a 3.9 computer if you retrofit the 3.9 front cover , dizzy etc and get a modified chip from UK.
Regards Philip A

[disco95]

So probably better to work the 3.9?

[davew]

You could always use Megasquirt to run the 4.6, if it's a Thor or GEMS it'll run either without much problem.

If it's a GEMS 4.6 the 3.9 ECU could probably run it anyway, for the most part you could use the 3.9 engine loom as is in that case.

[awright]

les Richmond in melb adapt holden computers as well even if the motor is too far out of spec for a 3.9 to run it. Or use an aftermarket, hawk, wolf, etc.