SD to MAF conversion firing order question
 

OK I broke down and bought a SEFI harness and MAF kit from RJM. They did a real nice job on the harness for my conversion. My question is

What firing order will I need to go with now that I am using a HO A9L computer from a mustang?

My cam is for a truck

The new harness from RJM is has its pins marked for the mustang computer

I am going to run a single O2 sensor that is made into the harness

Do I stick with the original 15426378 with the new SEFI harness wiring?

Thanks
Jesse

Depends what firing order the wiring harness is pinned for.

What year truck?

The truck is a 92 SD motor with an original firing order of 15426378.
The harness is made by rjm injection for the truck because it only has 1 o2 sensor.
The pinout on the harness is for the 87-93 mustang 5.0 computer which I believe is a sefi setup.

Thanks I hope this answers the mail. Jesse

Not quite actually. I know the harness is designed for the mustang computer which uses sequential injection, so what I was asking is what order are the individual injector wires routed for, or specifically do they have the harness laid out to fire the injectors sequentially in the old 5.0 firing order or the HO firing order?

Thanks for the reply. As far as how the harness is it is hard to tell tell what it is wired for. I mean it is laid out with 2 wires per injector with 1 wire for each going back to the computer. I will need to integrate the harness to the existing plug to mate with the new computer.
Injector 1 has 2 wires returning to the computer but the others have only one. I imagine the feed is the same so it is common among the rest of the plugs. The wiring is as follows on the harness
Injector Pin
1. 57. 58
2. 59
3. 12
4. 13
5. 14
6. 15
7. 42
8. 52

Again thanks for all the assistance.
Jesse

Because the cam in the motor is setup for the 15426378 firing order, you have the run it with that firing order so I would say you have to do whatever you need to set up the injectors to work with that order.That being said, as long as fuel is present in the incoming charge, the spark plug will ignite it. It is not like a diesel where injector timing/order determines when the cylinder fires.

So are you saying the harness has pigtails with pins that are to be inserted into the exist truck EEC connector? If so then you're good and here is the pinout you will have to follow.. grey wires to be added, color wires to be moved. And because your truck has a cam with the non-HO firing order you will have to switch pin locations for injectors #5 and #3 and injectors #4 and #7. Clear?

http://farm5.staticflickr.com/4017/4...697_z.jpg?zz=1

Many thanks for the explanation. You all have been a great help and I plan to get this done real soon. The pin out you sent will be a great help. Only question for clarity is is that inj 5 will go to eec 12 inj 3 will go to eec 14 right? The same idea for 4 and 7. This swap out will allow the injectors to fire with the timing. I really hope it makes a big difference with this cam. Sorry for so many questions. i have learned alot here though. Thanks
Jesse

Yep you got it.

Stock cam? If so don't get your hopes up, it may run a little smoother but you won't see any more power.

Awesome thanks for the help. The cam is actually a little lumpy according to the PO but he said it was for the truck. If that is true I think there should be a good improvement. It is a comp cam that was bought but I'm unsure of the specs since I bought this as a unfinished project. Hope this works as I cross my fingers. I will keep the forum posted on my results. Thanks:)

I've been readings alot of these threads, will all the stuff from a 94-96 MAF with the same trans work for these swaps ? I assume the cam and ECM would have to go with it too, I see most people buying some aftermarket harness and making a science fair tranny controller. Seems too easy to get the factory stuff from the junk yard.

5.0 HO engines (Mustang) used a different firing order. Therefore, the camshaft was also tailored for that firing order.

In reality, the firing order which the computer is "feeding" the coil, is IMMATERIAL. All that matters is that the plug wires be inserted into the distributor cap in the correct position which the computer being used fires the cylinders, for the firing order the camshaft follows. One could also swap the positions of the plug wires at the COIL, instead of the distributor. Be aware that this is true for SEFI, as in Mustang, and NOT batch fire, if that is what was present originally. impish

PS: I believe the batch fire coil will not operate in SEFI, and will need to be changed to an SEFI coil. AND, the injector connections must be appropriately changed to follow the SEFI firing order.

To clarify a bit: here are the two firing orders Ford used for 260, 289, 302, 5.0L, 5.0L HO (High Output), and 351W (or, 5.8L)

1,5,4,2,6,3,7,8 was used on all except 5.0l HO and 351W

1,3,7,2,6,5,4,8 was used on 5.0l HO and 351W

Looking at the two, note 1, 2, 6, and 8 are in the SAME POSITION in both firing orders. So, if you are using a computer programmed to fire in the 5.0L order, you simply keep 1,2,6, & 8 plug wires in same location in distributor cap, put 3 in 5 location, 7 in 4 location, etc. EITHER computer divides the firing pulses into 8 even "time events" as the crankshaft turns, and energizes the injectors similarly, (though obviously earlier than the spark), so injector wires must also be appropriately re-connected. Remember, the camshaft in use must ALSO use the appropriate firing order.

The 1,3,7,......order was used in Mustangs and some Lincolns, possibly some T-birds as well. Ford Engineering believed that loading on the front main bearing was lessened by using this firing order.

I should think the transmission couldn't care less what firing order is in use, or whether SEFI was in use, or not. BUT, if a PCM is changed, and it is not programmed for the transmission in use, (electronically-shifted), problems are a certainty. impish

The later (94-96/7) 5.0L uses the Mustang and 5.8L firing order. Where you may run into a plug and play issue is the large (C202) connector through the firewall. Ford has changed the pin layout several times for various reasons. Biggest being the addition of airbags starting in 1994 on the under 8500 GVW trucks. The airbag module has a number of through the firewall connections. 1996/7 are OBDII systems and totally different, crank sensor and cam sensor are separated, 104 pin vs 60 pin, EEC-V vs EEC-IV.

The transmission type can also give you fits, AOD-E/4R70W and E4OD wiring is quite different, and again, Ford changed the wiring a few times, not the function or color, but the connectors. The 42 way engine harness connector also changed a few times (ask me how I know these things).

Most of the transmission shift points are ultimately determined by a max RPM so over revving shouldn't be a problem, MPH shift points may be high or low depending on rear axle ratio differences. If it is a real problem, than you may have to get a custom program, or buy something that will let you do your own programming. There is a forum on here for that.

Most informative post! Thank you for that! (BTW, how DO you know these things?) impish