The Ford EFI computer harness is basically a stand alone system and only requires about 5 connections to be made for the computer to function. (assuming that all sensors are in place.) The wiring and electrical connections on this conversion are pretty straight forward. You should not be intimidated about wiring.
Here is a shopping list to help with gathering components from the Mustang 5.0 EFI system for your Mopar.
You'll need the following:
- 89-93 5.0 Mustang computer. (Make sure that the donor car has a mass air sensor)
- Engine wiring harness. (The Mustang’s wiring harness is in 3 main sections. There is the main wiring harness that connects
to the computer. There is the O2 sensor harness that plugs into the main harness and runs to the O2 sensors. And, there
is the injector harness that connects the main wiring harness to the injectors and other related components on top of
the intake manifold. You need all three.)
- BAP sensor (Barometric Air Pressure Sensor - black box on the firewall)
- Ambient air temp sensor (in the intake manifold. Cheap if purchased new from local auto parts store.)
- Water coolant sensor (not gauge sensor. Also in the manifold, and cheap if purchased new.)
- O2 sensors (They are probably better new because it is very difficult to get them out of old junkyard exhaust pipes.)
- Ignition coil
- Distributor, cap, rotor and spark plug wires.
(General rule: If it is on the firewall and is connected to the wiring harness, take it.)
Now these next few items might need to be upgraded depending on the horse power out put of your engine.
- mass air sensor
- fuel injectors
- throttle body
The stock Mustang mass air sensor is 55mm, the injectors are 19 lbs and the throttle body is 60mm. These components will work to get the engine running and will allow enough air and fuel into a V-8 to support about 280 to 300 horse power. (Remember, the stock 5.0 Mustang only put out 225 HP.) If your engine is putting out more horses that that, you might want to think about upgrading these components.
If you decide that you need an aftermarket throttle body, get the stock, Throttle Position Sensor that sits on top of the stock throttle body because aftermarket throttle bodies usually do not include this sensor.
The Fuel Injector and the Mass Air Sensor are related. To understand this relation, think about changing carbs. If you change to a bigger carb, you are changing two things. 1.) the bigger carb lets more fuel into the engine and 2.) the bigger carb allows more CFM of air into the engine. Fuel injector size must match the calibration in the mass air sensor for everything to function properly. So if bigger injectors are required for your Mopar’s thirsty horse power need, get them and make sure that the mass air sensor matches the injector size. Any aftermarket mass air sensor can be purchased to match your injector size. For example, I am running 30lb injectors and a 73mm mass air sensor and a 70mm throttle body to ensure that my Mopar’s engine doesn’t starve for fuel or air.
All stock Mustang throttle bodies are connected to an EGR spacer and have an EGR Sensor connected to it (Exhaust Gas Recirculation sensor). This is an emissions item that is not necessary for the computer to run. Most Mustang guys eliminate this for race applications anyway. I also eliminated this EGR spacer, but got a neat little electrical plug from Ron Morris Performance to plug into the wiring harness. This electrical plug makes the computer think that the EGR sensor is still plugged in. This ensures that there are no engine–check codes for getting rid of the EGR stuff.
This brings me to the Distributor. This was a huge concern of mine when I was designing the swap. Ford’s wiring harness plugs into the distributor. I figured that I would have to take a Mopar distributor and put in Ford guts. Instead, I came up with a better solution, I made the Ford EFI distributor fit the Mopar’s engine. I worked with a local machinist that machined a base for the Ford distributor so that it would mount into the Mopar’s block. He did some work on the distributor ‘s shaft and eliminated the Ford’s distributor gear and it was done. The hybrid distributor was born. This hybrid distributor is a key piece of the EFI puzzle. With this distributor, everything becomes a lot easier. This machinist can duplicate the distributor if others are interested.
The last big key piece to the puzzle was resolving the firing order differences without offending the computer. Since the Ford’s firing order and the Mopar’s firing order are different, I had to do some custom work to the Injector wiring harness so that everything would function optimally. I worked with a fantastic Ford engineer to come up with this solution with brilliant results. I’ll discuss this later. I’m getting tired of typing. I hope that this helpful to those that are interested in an inexpensive EFI option.
And, by the way, my gas guage broke right before the swap (rats!), so I don't have any actual numbers to share yet. But, I know that the mileage is better. In addition, I get incredible low end responsiveness and torque. The engine feels REALLLLLLY crisp and razor sharp. There are no delays, no hesitations, immediate cold starts and all around improved drivibility, and it pulls like a run away freight train when you nail it. It also looks pretty tricked out when you pop the hood.
Out of curiosity, has anyone else other than myself, owned a fuel injected 5.0 Mustang or has any experience modifying or racing Mustangs?
