Found! IAC or TPS for 2.8

[franklin2]

I do still have to pass emissions and I think with the duraspark conversion you get codes that prevent that, right? I may be moving to a new state soon and would happily make the swap as long as I can register it like that haha. Thank you for everything, I'll try to track down that manual and adjust the carb tonight!

You will not get codes if you do not have a computer. Of course if they plug into the vehicle to talk to the computer, they will not get a response. It will not be there. You can pull the computer and all those wires and sensors associated with it, you will be reverting your engine back to late 1970's operation.

I would be surprised if they plugged into a vehicle this old at the inspection station. It has no check engine light from the factory. But I guess you never know. Your system is known as the EECIV system. And they did use this same system to run the 5.0 mustangs, and all their fuel injected vehicles, till OBDII came out in 1996. After that they still used a updated version of it.

 

[natertot]

You will not get codes if you do not have a computer. Of course if they plug into the vehicle to talk to the computer, they will not get a response. It will not be there. You can pull the computer and all those wires and sensors associated with it, you will be reverting your engine back to late 1970's operation.

I would be surprised if they plugged into a vehicle this old at the inspection station. It has no check engine light from the factory. But I guess you never know. Your system is known as the EECIV system. And they did use this same system to run the 5.0 mustangs, and all their fuel injected vehicles, till OBDII came out in 1996. After that they still used a updated version of it.

I believe they do a dyno and exhaust sample. They won't read the codes, but I was under the impression that duraspark conversion would cause me to fail emissions. I'm already neck deep in restoring it with the emissions stuff and I'm 90% of the way there, so I'll probably keep on trucking until I can't afford it.

 

[natertot]

I can't remember where I got it, I have several manuals laying around.

I had a 2.8, was all original. But it would not run correctly. It would suddenly have a fast idle sometimes, I never could pinpoint it. So I took this system off, bought a regular carb from Amazon and bought a rebuilt distributor for a 1978 Mustang II with a 2.8. This distributor is the conventional style that does not need a computer.

The 2.8 in the 1970's was not computer control. So you can convert over. Problem is, everyone was converting, and the supply of the 1970's style distributor for the 2.8 dried up. I haven't looked lately, maybe you could find one if you wanted to go this route. There are some threads on here about people looking for a conventional distributor for the 2.8, and I believe a different style is being made in England that you might be able to source.

As you said, this system is old and can be difficult to work on. Some parts can be hard to find. It did work well when it was new.

Just an update because you gave some really helpful advice - I followed those instructions exactly and the ISC and fast idle were both way out of wack, definitely needed adjusting. It doesn't run any better though, and I still get the codes. I did skip the anti-dieseling step at the end because I couldn't locate that screw. Thank you anyways!

 

[franklin2]

I believe they do a dyno and exhaust sample. They won't read the codes, but I was under the impression that duraspark conversion would cause me to fail emissions. I'm already neck deep in restoring it with the emissions stuff and I'm 90% of the way there, so I'll probably keep on trucking until I can't afford it.

This system worked good when it was new. I liked how the computer controlled the rpm of the carb. The auto choke on the older non-computer carbs was always finicky to adjust, it raised the rpm when the choke was on mechanically. But besides the highest fast idle setting, the computer controlled the rest of the idle during warm-up and it was a lot better than the old system. They got very good fuel mileage also.

But when things go wrong, they can be a bear to fix and get working properly.