1990 2.9L to 1990 5.0L EFI Wiring Questions

[mrwesmrwes]

So I'm putting a 5.0 from a 1990 Mustang into my 1990 Ranger that used to have a 2.9. I have the main harness and computer from the Mustang and as I was removing the computer and harness from the Ranger I found that after the computer the harness goes into the under hood fuse box. The Mustang wiring harness doesn't have a fuse box attached to it.

Just wondering if anyone has already done this same swap and how I should make it work before I start cutting into it, if I don't need to.

 

[RonD]

Welcome to TRS

Good page to bookmark here: http://www.therangerstation.com/tech_library/index.shtml

In the engine section under wiring, there is "5.0l EFI wiring": http://www.therangerstation.com/tech_library/EFI_Wiring.shtml

Also the V8 swaps in same section

Most people use Explorer V8s and harness/computer, so are using the newer EEC-V 104 pin computers, you are using the older EEC-IV 60 pin computers, wiring of course is different but for engine fuse box connections it should be similar

This PDF has good EEC pin out descriptions, page 20: http://www.amopower.com/files2/technical notes on the EEC-IV.pdf
For 1990 period EEC-IV

And V6 pin outs here: which are similar for power and ground: http://www.auto-diagnostics.info/ford_eec_iv

PCM(computer) needs KAP(keep alive power) like radio does to hold correct time and pre-sets, so one wire will be for 24/7 power from engine fuse box
PCM powers up for starting when Key turns on and closes EEC Relay in engine fuse box, EEC relay powers injectors, spark, MAF, IAC, fuel pump relay and EEC(PCM), so its wire will be spliced in with those coming out of EEC relay

PCM also activates Fuel Pump Relay in fuse box, Grounds it, so one wire for that

 

[mrwesmrwes]

Hey thanks a lot! Those links have some great info and a good side by side comparison that I'm making use of this weekend. I went with the older 60 pin computer since it originally had that and I thought it would be easier. If you have any more advice just let me know. Thanks again!

 

[Dmgctrl88]

I converted my existing 2.9 harness. Used a mustang engine, crown vic roller cam for low end.

It was easy converting the 2.9 to 5.0 using an F150 computer, they both are similar and both use batch firing for the injectors. I have charts and a wiring thread as well on this sub forum.

Good luck.