Mark Houlahan
Tech Editor, Mustang Monthly
December 1, 2008
Contributers: Don Roy Photos By: Courtesy the Manufacturers, Don Roy

They don't make cars like they used to, that's for sure, which is actually something we can all be thankful for, particularly if we're talking about the fuel system in your car or truck. Remember the good ol' days of carburetors, needles, jets, floats, choke plates, and vacuum-operated secondaries, plus gum and varnish to stick it all together? Don't forget about stalling, rough idle, percolation, cold starting (an oxymoron at best), hesitation, stumbling, surging, pinging, and fouled plugs. Yes, all that brings back memories, doesn't it?

The '89-'93 5.0 Mustang-based EEC IV fuel-injection setup is one of the most common swaps for carbureted Ford owners looking for an easy EFI setup.

The heart of any EFI system is the computer, also called an engine control module/powertrain control module (ECM or PCM), depending upon the company. A standard EEC IV 60-pin model is shown here (left). The most common is the A9L from five-speed mass air-equipped 5.0 Mustangs.

But things were so much simpler then. You could tune your car with a screwdriver instead of a computer and, as long as you didn't put too stringent a definition on performance, things stayed simple. But who are we kidding? In search of more power, we'd strap on a new intake manifold, drop in a Holley 650, and head to the track. We and the domestic manufacturers explored a far-out range of carburetion possibilities, such as six-packs, dual-quads and triple or quad Webbers. Yeah. Things didn't stay simple for long.

Around the same time, the Europeans started playing around with this business of fuel injection in order to get more power out of their silly little engines.

In North America, there were a few notable experiments, including the '57-'65 Corvettes, which were equipped with Rochester fuel injection. Well, that turned out to be a good idea after all and now, 40 years later, you can't buy a car in North America that isn't equipped with fuel injection.

Open To Improvement
If you're already thinking of converting your small-block motor to fuel injection, you've probably heard of the many good reasons to consider the project. Among these are improved performance, higher horsepower and torque, better gas mileage, easier starting, and the potential for reduced emissions.

You can do the job fairly cheaply using OE parts from donor cars, if you don't mind doing some research and wiring yourself. There are also a number of commercial conversion kits that supply everything you need to get the job done, with a minimum of fuss.

So why does fuel injection work so well, anyway? In order to understand this, we need to look at what you expect from your car's engine and what the engine needs to deliver the goods. When you start up your car, it may be warm or cold, but in either case, the air/fuel ratio (AFR) needs to be somewhat rich. During warm-up, after starting, and during warm-idle conditions, the AFR is usually maintained slightly on the rich side so that the engine doesn't stumble when you want to drive away.

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