Ford Multi-Port Fuel Injection

A Ford MFI conversion is cost effective and efficient.

Feature Article from Hemmings Muscle Machines

August, 2005 - Jim O'Clair

The advantages to converting your Ford muscle car or street rod to a newer, more efficient fuel-injection system are similar to some of the reasons we highlighted when we featured the GM multi-port system a few issues ago. Many of you have seen aftermarket add-on fuel injection for your Ford and have considered trying it. But performing a conversion such as this one can be easily less than half the price of one of those add-on units. And you'll benefit from using easily found, affordable and easily replaceable Ford and aftermarket parts. The savings in fuel economy alone can be a motivating factor for any Ford enthusiast, given the current prices at the pumps. Even at a low-ball estimate of an additional mile per gallon, with some estimates as high as 3 or 4 highway mpg, it is easy to see how anyone can justify the expense of converting a carbureted engine to a fuel-injection setup.

Fuel injection can also provide a much more efficient burn of the fuel it is using, because the mixture is delivered directly to each intake valve at an even pressure. It will provide more power to the wheels and fuel injection can supply much better low- and mid-range torque out of a small-block Ford engine. This allows a smaller displacement V-8 to perform like an engine with more displacement. A '60s 289 or '70s 302 would be hard pressed to generate more than 300 foot pounds of torque without some major work, but this was commonplace for the Fox-body Mustangs and other Fords of the late '80s and early '90s. Fuel-injected cars also start easier than a choke-regulated carburetor and adjust for altitude and cold-start situations without any effort from the driver. They are easier to maintain, less prone to vapor lock in high heat conditions, and will meet state and federal emissions standards as well, because of their cleaner fuel burn.

Ford has offered a couple of fuel-injection types over the years. As the technology improved, as was the case with GM, these systems have become more efficient, while at the same time, still holding true to the basic Ford small-block engine design. This makes the installation of a late-model, small-block Ford fuel-injection system compatible with your older Ford carbureted engines.

Ford entered the fuel-injection era with a basic throttle-body system. This was first used on the 1980 Lincoln Continental 5-liter 302 and was referred to as Central Fuel-Injection or CFI. CFI first appeared in a Ford model in the 1981 LTD and they continued the use of CFI on four-cylinder engines until 1990. They were also used on six-cylinder engines until 1987 and eight-cylinder engines until 1985. Ford first debuted their multi-port fuel injection on the 1983 1.6-liter Escorts and the 2.3-liter Mustangs and Thunderbirds. Multi-port or MFI became Ford's standard fuel-injection system on all V-6 and V-8 engines in 1986.

Although a Ford MFI conversion is not as easy as swapping a carburetor, it is well worth your consideration when trying to improve the performance of a project car. This conversion involves a trip to your local pick-a-part to look for one of these donor cars, all of which were equipped with the 5-liter 302 V-8s:

o 1986-'88 Thunderbird
o 1986-'91 Crown Victoria and Grand Marquis
o 1986-'95 Mustang (except Cobra)
o 1991-'93 Thunderbird and Cougar with the H/O 302
o 1986-'92 Lincoln Mark series
o 1986-'90 Lincoln Town Car
o 1986-'87 Lincoln Continental
o 1986-'87 Lincoln Mark series with the H/O 302
o 1987-'88 Mercury Cougar
o 1986 Mercury Capri

We recommend these cars as your starting point for several reasons, the most important point being that the upper and lower manifold sections will retrofit into numerous '60s small-blocks. If given a choice between a few donor cars, try to concentrate on something newer than 1988, the reason being that a mass airflow sensor tuned the 302 engines from '88-'93. The MAF sensor is self-correcting, meaning once you install the system in your car, the MAF sensor will figure out the optimum air/fuel combination for your engine as it is currently configured. It will also take modifications into account when sending data to the computer, so it's not a big deal to change engine components. You don't have to upgrade the computer chip or reprogram the ECM either.

Some models in the '86-'88-year range use a speed-density-driven computer system. The speed-density system gets most of its feedback information from engine and throttle sensors. Additionally, the vehicle's speed sensor is attached to the back of the speedometer head. It does not take into account the air volume in any of its measurements. Speed-density-driven systems are not as adjustable as the MAF-based systems, and you may not realize the full potential of the system without the MAF sensor. A MAF sensor can be purchased and retrofitted, if you can locate or purchase the proper harness. In the case of the 1986-1993 V-8s, there are several aftermarket companies that offer a replacement harness for completing this exact conversion. You can also use the multi-port system from 1994 and 1995 vehicles but, when trying to keep costs low, this is not your best option. The EGR system on a 1994 or 1995 engine is different, being externally fed via tubes outside the engine. The earlier EGR valves from 1986 to 1993 were internally plumbed. The wiring harnesses that fit the 1994-1995 system components are not compatible with any of the connectors for earlier years either. Front engine accessories such as the timing cover and water pump are also different in the 1994 and 1995, and the connectors on the ECM are also different. You'll spend quite a lot of time and silver solder making a new adapter harness.

You will also notice we did not recommend any truck donor engines. In fact, we highly recommend steering clear of truck donor vehicles. Although they use a similar type of fuel delivery, the truck engines are non-sequential, meaning four injectors on one side will fire at once, instead of each cylinder firing on its own intake stroke. So it is easy to see how that can rob you of performance, which is one of the reasons you are tackling this job in the first place.

When you find one of these cars, here is what you need to complete the swap:

o Intake manifold and plenum with EGR valve
o Multi-port injection unit including throttle body, fuel injectors and fuel rails (with pressure regulator)
o Air box assembly
o Mass airflow sensor (if applicable)
o Coil
o EEC IV computer
o Distributor with EEC IV module (gray plastic module bolted to the side of the distributor)
o Ignition coil and bracket
o Main wiring harness
o Alternator
o Coolant sensor
o Air-charge sensor
o Barometric pressure sensor
o Vehicle speed sensor (either engine or speedometer mounted)
o Idle air bypass valve (usually attached to the fuel rail)
o Throttle position sensor (usually comes with the throttle body)
o Inertia switch (in the trunk)

Your fuel tank will need to be adapted to accommodate a return line from the multi-port unit. Fuel delivery will require an inline pump rated at 35psi minimum. You will also need at least one new heated oxygen sensor, which will need to be installed in the exhaust pipe downstream from the manifold, but before any converter or extension pipe.

Original applications used two of the same sensors on either side of the engine. You can drill a hole in the exhaust pipe and install an oxygen sensor bung adapter to receive the oxygen sensor or sensors, when you find a convenient location to install it. Remember that the farther away from the manifold, the more accurate the measurement from the sensor. Somewhere around 10 inches behind the last cylinder on that side would be optimum. A replacement sensor should have a three-wire lead to fit the original harness (Ford part number E6SZ-9F472A or F0SZ-9D472A). Aftermarket replacements for these sensors sell for $40 to $60 each.

Because of the additional amp draw required for the computer, sensors and fuel pump, it might be a good idea to consider upgrading your alternator as well, which is why we recommend that you get one while you're scrounging at the salvage yard. The later-model 2G (90-amp) and 3G-type (130-amp) alternators are compatible with earlier engines by changing from a serpentine to a conventional pulley. But realize that 90-amp and 130-amp harnesses are not the same, so you must stay with the donor alternator that the donor harness is coming from.

We also recommend that a relay be installed between the battery positive terminal and the ignition switch to safeguard the switch from the higher start-up amperage required on MFI systems. Re-installing the inertia switch is a safety requirement for fuel-injected cars. It must be mounted vertically to the body inside the trunk and complete the circuit to the electric fuel pump. This switch shuts off the fuel pump in the event of a crash or rollover, and the car will not run again until the switch is reset.

Fuel line pressure in a fuel-injected system is higher than conventional carburetion; therefore it is important that all neoprene hoses and fuel line clamps be fuel-injection rated. Pre-bent steel lines can also be ordered from one of the aftermarket tubing companies. Carter makes an aftermarket, inline fuel pump designed specifically for MFI conversions, part number P5000 ($140.00). This pump is rated at 45psi and 50 gallons per hour and is compatible with the required fuel return-line system needed to run fuel injection. Ford MFI is driven by a square wave-pulse signal, so using an early electronic distributor will not work with MFI conversions. Earlier non-EEC IV systems produce the standard sine wave signal. Aftermarket ignition modules and distributors are available that are fuel-injection compatible, but they are also on the pricey side. You can adapt your original non-EEC IV electronic distributor to drive this conversion by purchasing a tachometer filter, available from Affordable Fuel-Injection, MSD or Classic Instruments.

Adding the MAF sensor to your fresh-air intake will involve splicing of the ductwork into the throttle body. For some applications it may also be necessary to relocate the battery to make room for the air box assembly, or an aftermarket air filter can be used. K&N sells an aftermarket undersized air filter assembly for these conversions. This is the reason you often see fuel-injected late-model Mustangs at the drag strip missing their right headlight assembly. To get maximum efficiency from your MAF sensor, it is not recommended that you run an open-air filter. The more closed the system, the more accurate the sensor will be. In some cars, the wind turbulence created by the fan blade can degrade the accuracy of the airflow reading.

Checking with a few used parts suppliers, complete upper and lower intakes, with the multi-port fuel injection setup, can be acquired for $150 to $250. Expect to add on another $200 for a used matching wiring harness, $200 for an EEC IV-style distributor, $50 to $100 for a used computer, and 2G or 3G alternators are less than $100. You should be able to source the parts and complete the installation for well under $1,500. Custom add-on multi-port systems can cost between $2,700 and $5,000, depending on the desired performance requirements of the engine and which aftermarket manufacturer you decide upon.

For further installation information and tips, we would recommend you read Ford Windsor Small-block Performance by Isaac Martin and/or Ford Fuel-Injection & Electronic Engine Control: All Ford/Lincoln-Mercury Cars and Light Trucks 1988 to 1993 by Charles O. Probst. Probst also produces a pamphlet called Multiport EFI Engine Management Harness, which is available directly from Ford by calling their technical assistance line at: 1-810-468-1356.

We feel this conversion is well worth the expense and sweat necessary to complete it. The improved mileage your classic Ford will realize will help to justify the initial expense, and the performance and maintenance benefits of the Ford MFI are an additional bonus.

This article originally appeared in the August, 2005 issue of Hemmings Muscle Machines.

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