3.9 in to a 3.5

[way2deep]

hi ,a mate of mine has just fitted a 3.9 in to his 3.5 ...but the wiring for the ecu is different and the big block connector won't fit either.....has anyone done this transplant ?? if so how do you get around this problem....many thanks ..robbie

[hairyasswelder]

It is a different ECU and injection system. Hotwire and flapper,
AFAIK you can either use the complete 3.9 system inc wiring harness and ecu or use the 3.5 flapper system with ecu etc. on the 3.9 block.

[Range Rover Blues]

Yes I have, how desperate are you to get it done?

The 3.9 EFi likes to know a bit more about the car, like road speed, gear, airconn and heated screen etc.

You can get away with fitting the ECU and loom though, just ignore some of the connections.

Fit the loom and ECY under the seat, the relays go with it but you may need an earth.  On the 7 pin connector by your left foot you will have to dismantle the plug (pull the red card out) and relocate the pins to match the 3.5 EFi supply that's there, mine has 3 wires form the 3.9 ECY loom taped up doing nowt.

Best bet is to get hold of the haynes manual which has wiring diagrams for both, you can then trace which wires do what and what you need, what you can leave etc.

It is a very possible swap though and IIRC the wiring colours are the same on the 3.5 and 3.9, best to check though.