I am curious about swapping my 4.6 liter engine for a 5.4 sometime next year. I have read many posts here concerning this matter, and a common element seems to be splicing a current ECM wiring harness in to a donor 5.4's harness. This scares me a bit... I work in the electronics industry and would think all the shaking and vibrating a vehicle sees would quite easily cause a spliced solder joint to break. I'm picturing the 80+ wires coming from my ECM randomly opening and shorting at the splices. I don't need that troubleshooting nightmare. Granted if the splices are done right, I'm sure it's not a problem...but I know how hard getting spliced wires to be perfect and stay perfect over a long period of time can be. So, what I would like to know is:

Would I be better off buying an ECM for a 5.4 and installing it with a new engine? Would this solve the wiring issues completly? Would my tranny and gauge cluster mate up to a 5.4's controller? I'm guessing maybe no on the tranny, since it is not the same as the 5.4's, but I could just get the 5.4's tranny to go with the swap. Any other major issues? I'm sure a book could be written on a swap like this; I'm just looking for the high points...or road blocks.

Thanks!

Mike

 

First, what year is your truck? If you already have a 4.6 with the COP ignition, you should not have much difficulty.

Also, I dont think there is much splicing involved either way. For the most part, the wiring is the same except for the ignition system. All 5.4s use the COP ignition, and as I said, the 4.6 didnt get this until 2001. If your truck is pre-2001, you will have to find some sort of work around for that.

I would not bother changing out the ECM. Your best bet is to get a tuner and explain what you are doing. Troyer Performance has done a few of these. I suggest you search for posts that include "swap" by the user JMC, he has done the swap and he has already posted just about all the info you need. You can always message him if you need more help, or talk to Troyer, he can also give you some guidance.

 

Sorry about that, I did leave out the more important details. The truck is a 1999 Supercab 4x4. So, no COPS ingnition system. Not sure about PI or non-PI heads. I have heard it could be one or the other for my model year, depending on rather it is a Windsor motor or not.

Thanks for the feedback. I figured there were quite a few things that had to be modified. Sounds like I may be worrying too much.

Mike

 

i say stick with ur 4.6 if u do a swap do a DOHC swap or a PI motor swap for the 4.6

 

I don't think splicing the wires is the answer. If you are going to do a swap find a donor 5.4L truck at a wrecker. That way you can rob a complete harness and the ECM also. I would think that the firewall connectors would be the same. Someone on here may already know how far back you would have to go to get to a comon connector point.

 

Take a search through JMC's posts, he did this not too long ago.

I don't recall how much detail he put into the threads on the topic, but it is worth a look through his posts to find the details.

 

The 4.6L computer and harness will run the 5.4L fine with minor changes, you will need a chip to get everything out of the engine. The 5.4L will run just fine off of the coil pack and wire ignition, you will not need to switch over to the COP ignition.

 

Screw the 5.4, go with the 6.8

 

trying......