I recently installed said engine in a 94 f150 which had maf sensor. I used
94 harness because it was in better shape (actually has coating on wires) and 94pcm 93 computer. ( It Didn't like my 93 pcm) Runs fine but pings.(believe fuel injection firing order is problem) Haven't been out of driveway yet. I've read about everyone wanting Maf . I've got everything for maf. But firing order is different on the 93 302. From what i've read I need to rewire the injector harness to match old firing order. And then can use 94 computer. Any Ideas as to what needs done.

 

If I'm viewing this correctly, all you need to do is check to make sure you running a 351 firing order from your dizzy to your plugs.

 

The firing order of the 93 302 is not the same as a 351. But will work to change firing order via plug wires? I thought you had to change cam to change firing order. thanks

 

This is an interesting problem - you will have a Multiport Sequential EFI activating the injectors in the wrong order for the 93 engine. You can get some interesting problems if you rewire the injectors, because the engine will think the injectors are physically in the proper locations, even though they're not. If you have two oxygen sensors, the engine will try to lean or richen the mixture on each bank of cylinders as the engine runs - but now two of those injectors are on the other side of the engine, and adjusting the mix throws off the opposite bank. Make sense? Multiport sequential also has a cylinder balance diagnostic feature that will not work correctly because the injectors are not where the engine thinks they are.
To really make this right, you either need to use the 93 harness and PCM, or install a 94 cam to correct the engine firing order. Mass air is nice to have - I'd just switch the cam and be done!

 

If the cam is still stock (93), the you'll have to modify the injector harness and plug wires to match the cam timing/firing order.

 

I thought as Much. 94 intake is on engine I Believe only has the one oxy sensor. But will check. The 93 harness I have is shot (bare wires it a wonder it ran so well in old truck.)
I wish I would have found you guy's before I bolted everything up.

 

The engine is using the 93 firing order , I'm going to try wire harness rewire. I have a spare 94 harness if won't work. thanks

 

You should be able to just move pins either at the computer connector or at the injector harness, which keeps you from having to cut or splice any wires. Swap injector 5 with 3 and injector 4 with 7 and you should be good to go using the harness and computer that came in your truck.

 

THANK YOU THANKYOU You guy's are great. So all I have to do is unwrap my harness
to tell what wire is what. There wouldn't happen to be a somewhere that could get color code or pin location? My manual is for 92 96 but they don't have newer 94 up harness in it. By the way truck runs great other than fuel injection problem. Boy the air induction tube with MAF make alot noise. Sounds like 400m with carb and air cleaner lid flipped. gota love it.

 

so your 93 ecu is a mass air ecu? If i am reading this right that may be your problem because i didnt think mass air was available in 93. why not locate a 94 mass air ecu and not worry about it.

 

I have a 94 mass air ecu . Tried it first. Ran Bad . The 94 has different firing order . I was going to switch injection order to match 93 engine and can try the 94ecu. Only have 93 ecu in because truck starts and runs

 

What wiring harness are you using with the 93 computer? I wouldn't think that a batch fire ecu would even operate the engine at all through a mass air harness.

If you have a multimeter, use the continuity function to determine what wire serves what function. It's a lot quicker and easier than unwrapping the whole harness and tracing the wires by hand.

 

You mentioned having a complete 94 harness that came with the same 94 motor you have now with the 94 ECU...

 

I'm using the 94 harrness and yes it does run but I know its not right. has all the same sensors ect as 93. only diff is Intake air temp sensor is on air box instead of manifold . It still has same colored wires. And maf but And just after my last entry I thought about multimeter to test wires .Duh. to much time in the sun. As my first entry said 94 f150 with Maf sensor,94 harness, 94 pmc ,93 computer(till figure out wires, then 94 comp to take advantage of MAf.

 

Something isn't right...the speed density computer on a 94 mass air harness would only be firing two of the eight injectors.