truck 302

[Archangel]

It has the HO firing order, it has 19lbs injectors, but it also has batch fire ECM - can the stock ECM be swapped out for a Mustang or Mark VII ECM so that I end up with a real SEFI engine? Or I'll need to swap out injector harnesses too? This is for a late '80s to early '90s trucks by the way... Also, what tranny would one of these things have in a 2wd form? AOD, E4OD, something else? if E4OD, does it have electronic controls, or everything is purely vacuum/mechanical?

[gadget73]

Need to re-pin the harness so the injectors are wired for SEFI. By default, there are only 2 injector drivers on the trucks, so one pin has 4 injectors, the other pin has 4. HO firing order eh? Must be a 93+ truck. Earlier ones had a flattie cam with the 289/302 firing order. The cam changed in 93 to the same roller cam the Explorer got, which has a 351/HO firing order. Not sure on the trans, you'd have to check. It could be an AOD, could be the E4OD which I do believe has electronic inputs.

[Archangel]

hmm, well it ain't no '93 truck, one is an '86 and the other a '92, both 302 engines. So if it ain't no HO firing order, can I just swap out harnesses and run a Townie/CV/GMQ harness and computer?

[gadget73]

I wouldn't. Towncar ECM is going to expect 14# injectors. The batch fie system also uses only a single O2 sensor. There are some guides over on fordfuelinjection.com about switching over a Bronco to EFI, and I swear somewhere I've seen one about converting a batch fire to sefi but I can't locate it now.

Moving it to SEFI will give you a little more fuel economy, but it doesn't really make any more power. Throttle response might be a little better and emissions will probably drop a bit. What are you looking to do with it exactly?

[Archangel]

daily driver, with decent fuel economy - considering an F150 short stepper is lighter than Townie and most likely geared better in the axle it should be entirely possible to see 18mpg and up, don't you think? I know the Townie ECM expects 14lb injectors, but the E7 heads trucks have flow better, so they will need more fuel, right? Also can't I just splice the left and the right O2 sensors harnesses together, this way ECM will receive two signals it wants, it will be the same signal in both sides, but it will be two separate inputs. How about that?

[gadget73]

Its more the cam that will want the extra fuel. You can't plug a 19# injector into a computer that expects a 14. It will spray for too long and run really super rich. Also not sure about splicing the O2 inputs. It might work but I don't know how well it will trim the fuel. Ideally, the ECM's firing order needs to match the camshaft's firing order, otherwise it won't end up trimming fuel quite properly.

[Archangel]

So I need an AOD tranny (no interference with ECM), an HO ECM, and an HO harness to repin so that the HO ECM fires in the non-HO order. Also two O2 sensors - looking at pictures of exhaust manifolds, it looks like both manifolds are tapped for O2 sensors, and also the shape of the 5.8 manifolds is very close to that of the 5.0 only with larger collectors - that will be a cheap exhaust flow upgrade right there, and solves the dual sensor problem too... will see how things go, if you have any other suggestions please share

[Pirate]

One other note: the truck 302 has a knock sensor in the block....I don't know which ECM you were going to use, but I thought I should warn you...

[Archangel]

Well the Mustang and Townie ECMs don'r look for a knock sensor, do they? In that case, can't I just leave it unplugged?

[Pirate]

Well the Mustang and Townie ECMs don'r look for a knock sensor, do they? In that case, can't I just leave it unplugged?

Yes. I wasn't sure which ECM you were going with....although I have gotten a 1987 T-bird 5.0 ECM to work in a 1991 Ford F-150 before, and it actually ran okay.

[Archangel]

the '87 T-bird has a non-HO engine, so its ECM would ask for 14lbs injectors - how did you make that ECM work with the truck engine, did you swap out the injectors? Also what about the two O2 sensors, how did you go about that?

[gadget73]

Honestly if you're going to go through all that trouble, I'd probably consider just stuffing an Explorer cam in there and run a Mark VII ECM. Somewhat more agressive cam, lower friction valvetrain (roller), and its the right firing order so no need to worry about the fuel trim going wierd. Its possible to re-pin the harness and all but it won't be able to tweak the fuel quite right if the engine firing order doesn't match what the ECM thinks it is.

[Archangel]

well what about the two O2 sensors - the Mark VII ECM will be looking for them, and there's gonna be only one in the truck harness... besides converting to a roller cam requires removing of the intakes and fuel rails and all the other BS on top of the engine, and that takes some time and asks for a garage and I ain't got neither. On the other hand I can mod the SEFI harness a bit at a time, then just go out and pull the old one out and put the new one in for like an hour or so.

[Mercracer]

If you have an 80s truck with a HO firing order and 19 lb injectors, you have a 351W.

[Archangel]

Ah, so 351 got the HO firing order, but the 302 didn't? Well then, will a HO computer off a car run the truck 351, provided harnesses are swapped to allow for SEFI? I mean these ECM are calibrated for a 302 and 19lbs injectors, how adaptive are they, will they tolerate an 49ci increase in displacement?