im in the process of putting a mustang mass air computer and harness in my 85 F150 4x4 manual trans. all emissions things are gone and harness was stripped and redone to accomidate wiring lengthening and such. after just working on my brothers car the vss sensor was bad. this led me to wonder about my harness. a guy from ford performance parts told me I didn't need it for computer to operate. the 1 on my mustang I had was busted off and cruise control was inop. my car ran fine and didn't stall. im running an automatic computer in my setup cause I have a spare one as backup and the timing is different compared to a manual computer. mustang and ford car foums say you have to have them so my question is do I need the vss and what adapter do I need for my transfercase

 

It would depend on the computer part number and the programming. If you have stripped a lot of stuff out of the harness, it's not going to run right and give a lot of codes since that stuff is missing. Now if you have a different computer that does not require/look for that stuff, then it will be ok since it's been programmed that way. Same with the vss. If it's programmed to work without it, then you would not need it.

Since you are running a automatic computer, I know it will not be happy since you do not have some of the automatic connections. Unless they have been programmed out of it.

You know these things will run like this, with all this stuff missing. But it will be in open loop mode.

 

I am using an A9p computer which is for an automatic stang my brothers 91gt auto has the same computer. on oldfuelinjection.com it doesn't list any of the emissions things. and the tech guy I called years ago said it would run fine without the emissions, but never said anything bout codes. he never mentioned the vss. and the stang I had had it broken off and car ran fine but according to any stang forums you need it so if I do need it what adapter or trucks in junkyard could I use

 

from what I read if I connect pin 30 to clutch pedal and pin 46 when I push in clutch it should idle down. once the engine meets all requirements it should go to closed loop, it would only go to open loop if sensors are disconnected all emissions things are solenoids ie tab,tad,can purge,egr vac. (from what I read) if I do need the vss and hook it up how will engine be affected if I have it in 4low. I understand it changes air/fuel ratios according to speed but in 4low I don't want power to b affected cause wheels aren't spinning as fast

 

I looked the vss up in a book I have. It's used for;

to control the lock-up function of the torque converter.

cruise control

to control the speed of a two speed electric fan when the vehicle is so equipped.

So your automatic computer would have a connection for the vss. If you do not hook it up, you will get a vss error code. If you had a manual computer, it may not need the vss.

The EGR has a EGR position sensor or a EGR pressure sensor. The computer opens the EGR solenoid, and looks for a input from the EGR sensor, what ever kind it uses. If the sensor is not there, it will set a code.

That's the way tech's work on these things. They can get complicated, so the factory added diagnostics to help people work on these fuel injected engines. If it see's something wrong or something it doesn't like(like something missing) it will set a code, and do various things because of it. I have read that when the EGR has a error, the computer will not advance the timing as much to compensate for it being gone.

You are on the correct site(the fuelinjection.com). Keep reading. Look at all those 2 digit codes in the code list. They will be set when something is wrong with that particular part of the system, and if that part is missing, the computer will take that as something being wrong.

 

ok, well I guess I will have to get a custom chip made so I can get rid of the vss problem and a mil eliminater plug for the egr valve unless I can have that issue programed in the chip as well