It's about a '91 351w in a Bronco with a ZF. :)

So far I've got...
A9P Mustang (auto trans) computer
MAF sensor (hoses, housing and wires) out of a '93 Crown Vic 4.6L

I keep seeing...
"get a wiring harness from a ___"
I don't see that as being easier for me, since I can wire stuff. ;)
I just need to figure out where the wires need to go. ;)

1)
The MAF from the '93 CV has 4 wires.
The Mustang's MAF looks like it had only 3 wires.
The extra wire on the '93 CV's MAF is a ground.
Everything else looks the same. :)
Have any ideas on what I need to do about that ground wire? :)

2)
The '89 Mustang used "3 wire" oxygen sensors and I've read conflicting
information about them. :/

Is it as simple as buying a pair of 3 wire sensors for an '89 Mustang and
plugging them in? :)

Seen where a jumper wire was added (or moved?) on an O2 plug.
I guess to fool it into using a single oxygen sensor?

Saw where a trace was burned up on a computer too, from plugging in
4 wire sensors instead of using 3 wire, is that what happened there?

Is there more to the "4 wire" sensors than just a simple added ground
wire? Read where some oxygen sensors have resistors added to the
plug itself. I guess just to bias the current or voltage on those?

The extra wire goes to pin #49 on the '91 Bronco computer.

The Ford '91 Emissions/Diagnosis book it sez:
Pin #49 = Heated Exhaust Gas Oxygen (HEGO) ground.

3)
Is there something in the '91 Bronco/F150 speed control's sensors and
wiring to keep it from working with the '89 Mustang computer?

Alvin in AZ

 

Well yes you need to know where the wires go but you also need the special connectors for the MAF meter and injectors and also the pins that go into the EEC connector... because there are no pins in the locations for these components on your truck wiring harness. The wire itself is common but you won't find these pins and connectors at the local parts store, so this is why it's recomended to get a donor harness to steal what you need.

The sig return(pin9) is essentially a ground reference for the MAF signal(pin 50), the 12v supply to the meter heating element(pin 37) has it's own ground(pin 40)

Yes.

Yes the Ford conversion kit does this, just tie together pin 43 and 29.

Pin 49 is also HEGO Gnd on the mustang computer to so the 4th wire has no effect.

Probably not. A burnt trace on a computer used for a conversion could be from using an auto processor on a manual vehicle. An automatic transmission EEC, such as an A9P, applies a voltage to pin 30 whereas a 5 speed transmission applies a ground to pin 30. Using a 5 speed EEC, such as an A9L, without harness changes will likely harm the pin 30 circuitry and cause idle hanging along with a host of other erratic behaviors.


No.. as long as everything is on the right pins. There are several other devices that have to be moved because of conflicts, the canister purge, TAB and TAD solenoids, and something else I can't think of...

 

Yeah, I forgot about that need. :/
Dismissed that need early-on since I have a parts truck. ;)

After studying up on this a little looks like it'll work with or without that wire
connected?

Looks like most of 'em connect it to ground as part of a conversion.

But I still feel unsure about that dangged ground wire. LOL :)

Cool thanks, was just wanting to understand it. :)
I'm not planning to use just one oxygen sensor. :)

Cool thanks, I had that mixed up but you straightened me out with your next
piece of information...

Oh yeah, that was it! :)
Got mixed up, didn't do my home work as well as I thought. ;)

I need to study up on that some more, I'm using an auto computer with a ZF.

Cool. I know there's lots of "pin swapping" to do and I feel as tho that's
something I need to work out carefully, and for myself. Seems there are
too much wiring swapping going on for a guy to expect anyone else to
lay it all out for them and not get paid. ;)

I guess that's another reason for... "get a harness from ____".

Huh? ;)

Alvin in AZ