Engine swap 4.6L to 5.4L

Good morning,

The firing order is the same for both engines. There should be no issue with the firing order at all. Blow is the firing order for both engines and a picture of the cylinder identification.

V8 Firing Order: 1 3 7 2 6 5 4 8

As far as the ECM, it needs to be flashed by someone with the proper scan tool. Then that update will tell the ECM you have a 5.4 engine.

Roy

Hello my name is Dave.

You'll need a V-8 ECU and wiring harness to make that work. It doesn't actually matter if it's a 4.6 or 5.4 the computer doesn't need the displacement to function properly, I've done a LOT of conversions from 4.6 to 5.4 on these trucks, even put a 04 5.4 out of a Super Duty into a 99 that has coil packs, just had to make mounts for the packs. In your case you will want to make sure you get a compatible harness that has the same ABS module since it's a pain to take the harness apart and separate the ABS wiring from the ECU wiring. Shouldn't be too hard to find at your local self service salvage yard. And please believe me when I say either harness/ECU will work. I've had this debate with a few people but I've done a lot of them mix-matching years and never have a problem, even pass emissions. Also understand your transmission from the 4.6 won't bolt up to the V8. Please keep us to date on your progress. We look forward to hearing back from you and thank you for using 2CarPros!

I think Dave meant the transmission from the 4.2 wont bolt up to the
v8.

Roy