I don't think the computer is precise enough in reading the O2 sensors to be able to adjust the pulse widths for individual cylinders. Cylinder banks, yes, but not individual cylinders. I didn't mean that it could adjust the amount of air entering the cylinders.

You are right that the twin O2 sensor setup is better, but the computer was only programmed for one. Even if you were to wire in another, the computer couldn't use the signal. Same goes for the BAP sensor - if it didn't have one, adding one won't make any difference; it's still not going to use it. The programming is the main reason for not being able to do this. Even if the physical circuitry was there, the software side of things is set to operate with one O2 sensor and without a BAP sensor.

 

just out of curiosity, how is it mechanically possible for a 302 to work with the old bankfire firing order as well as the H.O. firing order when using the same internals? i figured you would have to change the cam or something but i hear of people doing their MAF conversions on mustang and truck 5.0's without any mention of internal parts having to be swapped.

 

The MAF swap is purely electronic, so the physical firing order doesn't change. The crankshafts are the same on both orders; the cam is the only thing different. The 5,4 and 3,7 intake and exhaust are swapped, which is possible because the piston is at TDC twice for each engine cycle. The thing people change with MAF swaps is the injector order; the mustang computer commonly used is setup for the HO firing order, so to have it run properly on the non-HO order, injectors 5 & 4 have to be swapped electrically with injectors 3 & 7.

 

so i do not need to change cams yet? ive changed the firing order at the dist cap, and i assume the injectors. havent been able to get it to run well yet. but im not sure of my timing yet either.

 

You don't have to move the plug wires with the swap; the engine physically hasn't changed firing orders. If you have the 1-5-4-2-6-3-7-8 order, I would swap injector 5 wire with injector 3 wire and injector 4 wire with 7 wire at the computer connector (or where the injector harness mates with the main harness, whichever is easier). If your truck has the 1-3-7-2-6-5-4-8 order already, you don't have to change anything.

 

alright i changed to a 94 sfi harness for a truck that has the 1-3-7-2-6-5-4-8 order. my broncos' speed density 302 came with the old 1-5-4-2-6-3-7-8 order. are you saying i should go back to the old firing order by rewiring plugs/cap? or do i have to hack up the 94s engine harness?

 

Yes, and sorta. The engine still has the same firing order as it used to, the 1-5-4... order, so wire the plugs accordingly. The harness should be changed to make it work correctly, but should function like it is. The change doesn't require you to cut anything. I don't know how the '94 harness is set up, but if it is like the older ones, there will be a short harness of just injector wiring on the engine. If not, go to the point where the injector wiring meets up with the main harness. Take the pin retainer out (usually red plastic in the middle of the connector, mating side) and release the two wires that correspond to injectors 3 and 5 and just reverse their positions. Do the same thing for injectors 4 and 7. That should take care of any firing order issues.

 

"If you have the 1-5-4-2-6-3-7-8 order, I would swap injector 5 wire with injector 3 wire and injector 4 wire with 7 wire at the computer connector (or where the injector harness mates with the main harness, whichever is easier)."

- i would at the least have to unwrap some of the tape/corrugated plastic tube from the engine harness connection near the power distribution box and near the injectors to properly label and clearly identify which color matches which injector prior to pin swapping. i assume i only swap the unique colored wires and none of the red wires that they all have one of (the actuating/ground wire?)

"The engine still has the same firing order as it used to, the 1-5-4... order, so wire the plugs accordingly. The harness should be changed to make it work correctly, but should function like it is."

- so the spark would be in the old order and the fuel would be the h.o. order, and that would work(sustainably;without prematurely wearing stuff?)?

id try that first before repinning connections but youre making me think you're trying to tell me that the only correct way to do this is with my old style 1-5-4-2-6-3-7-8 motor to run the same old order (even with MAF) for both fuel and spark because my camshaft lobes are ground to open/close valves for that old order. nobodys explained it well yet, but that was why i was curious about whether it was workable for an old 5.0 to run the old and h.o. orders with the same internals. seems like no. but isnt the order (at least part of) what makes it or makes it not a sequential firing system? i always assumed bank fire=1-5-4-2-6-3-7-8 sequential= 1-3-7-2-6-5-4-8....

if i run mass air but retain the old bank fire order, have i truly converted to sequential FI. or will i have to wait until i build a 331 with the h.o. style cam?

thanks again.

 

The physical firing order is purely dependent on the cam. It just so happens that all of the mass air SEFI motors in the mustang and in the F150 had the 1-3-7.... order. The computer is what determines whether the injection is sequential or batch. With upgrading to a mass air SEFI computer and harness, you have sequential injection regardless of the order of the engine. However, your engine is physically firing in the 1-5-4-2-6-3-7-8 order, and the injectors are wired to fire in the 1-3-7-2-6-5-4-8 order. It will work being out of order like that, but the sequence isn't right, so basically at that point it isn't much better than the original batch fire. It will run, but it won't be right. To correct the injector firing order to match the engine firing order, you will need to swap the control wires (one for each injector, they all have a common power) of 5 & 3 and 4 & 7. I'm thinking this can be done without unwrapping any of the harness if you are careful. I'd get a multimeter that can test continuity and use that to find which wires go to those four injectors. Make sure the harness is not plugged into the injectors because you will get continuity through them and will get continuity on more than one wire.

If you are planning on building a new engine soon with the 1-3-7-2-6-5-4-8 order, it might be just as easy to get the current engine running without changing the harness. It all depends on if you want to swap those injector wires back when you install the new engine.

Does that make sense? Let me know if there's something you don't understand...

 

makes perfect sense. thanks for all the help. im gonna try starting it without rewiring injectors and then go from there. ill probably end up rewiring em twice;
once to get it to work 'correctly' with the old order, and again when i upgrade cams or motor.

 

swapped the pins and it seems to run much better. still havent got to drive it around because i still need to set timing to 10-11 degrees BTDC.

cant quite figure it out but i have no tach now. do you know where it gets its signal from? distributor, coil?? what should i test?

 

The tach should get its signal from the negative side of the coil. I would test the old harness to see if you can find where that wire passes through to the chassis harness. Then make sure that the wire is in the same position in the new harness.

 

SO, the truck has sat for a long time. I got it to run with the MAF, but the e40d wasnt getting the right signals and was shifting funny (I know why now). I've moved on and prepared to do a 351w roller swap, instead.

I have the roller block (f4te) out of a 95 f250HD, and a ecu and MAF sensor from a CA 95 f250. I've rounded up the light duty smog parts from a ca 95 bronco. I plan to modify my CARB approved 302 longtubes to fit the 351 style EGR. I have a 95 ford light truck EVTM coming soon.

I think I need to locate yet another mass-air truck harness, from a 95 5.8 light duty bronco/f150 to make this work, but I'm not sure if I'm going to run into the same trans wiring issues. From what I can tell in Haynes/Chilton, a 1995 CA MAF/SFI 5.8/e40d VINH truck (which has maf AND map sensors) has the same wiring to the trans as my 92 5.0 bronco (unlike the MAF/SFI 94-95 5.0 vin N trucks).

Can anyone confirm/deny that this swap can/can't work?

 

I don't know how I missed this thread but for some reason this is the first time have seen it.. hopefully I can be of some help.
It sounds like you are having a lot of trouble with the tranny and harnesses. I'd suggest you go back to the harness that the truck came with and use it as a building block for your project. This will involve identifying what all the wires are for as it stands, and how that compares to the computer you will use. You'll then need to isolate the sequential injector and MAF wires in one of the other harnesses, remove them and add them to your harness. This is a bit of work but considering what you have been through already probably not that bad in the big scheme of things.

I don't see you needing a different harness for the 5.8 motor, both motors have all the same components in virtually the same locations, I had no problems connecting a 5.8 to the 5.0 harness in my truck.

 

Okay, so you're saying unwrap my original 92 5.0 e40d harness, add in the wiring for the sequential injection, MAF, and IAT from the 94 5.0 harness and use the 95 5.8 computer?

Do you know a way to identify whether or not the 95 f250 computer i have is intended for a MAP, and one or two 02 sensors, after its been removed from the donor vehicle? the program code is ran2 and its not listed on fordfuelinjection.com.