Steve Baur
Former Editor, Modified Mustangs & Fords
October 13, 2010

If you've been around the Mustang scene for a while, you've probably heard of Fuel Air Spark Technology (FAST), or at least the aftermarket engine management system from the same company. Several years ago, Comp Cams acquired FAST, and the division's latest version of its engine management system became known as XFI.

While the XFI engine management system is a top-of-the-line piece, it requires a trained and skilled tuner to properly manipulate the software. The XFI system also has a price point to match its plethora of capabilities. FAST realized that there are far more do-it-yourselfer's with 400-500hp machines than there are racers with 2,000hp powerplants, and to fill this niche, it came up with the EZ-EFI system.

The FAST EZ-EFI system requires no previous fuel injection tuning experience, and you don't need a laptop computer to run the software. In fact, the EZ-EFI system performs its own tuning for you using an included wide-band O2 sensor.

The EZ-EFI system is available in a number of configurations, but the one that piqued our interest was the multi-port retrofit EFI kit (PN 302000). This retrofit kit is designed for use with the Ford EEC-IV 5.0L engine and other EFI applications, like GM's TPI setup. If you use FAST's XIM ignition module (PN 301313), you can install it on any Ford modular engine as well.

According to FAST, the EZ-EFI system will fire up to eight high-impedance injectors in applications ranging from street to full-on high performance. A simple yet capable handheld unit controls the system and provides on-board diagnostics, as well as a "check engine" LED display for maximum safety.

The included multi-port wiring harness is pre-wired for the most common GM sensors (yes, you'll have to run some GM parts on your car) and is fully labeled for an easy installation. FAST also offers a complete line of sensors, injectors, and adapters for other brands. The retrofit kit includes the self-tuning ECU, a wide-band O2 sensor with fitting and plug, a handheld user interface, a tachometer adapter, the multi-port wiring harness, and everything else you need for a quick and easy installation. FAST requires a vacuum-referenced fuel pressure regulator, like the factory Ford piece, with this system-one is available separately (PN Comp Cams 307030)-and a return-style fuel system.

At $875.99, the EZ-EFI system is not that inexpensive, but if you had to pay someone to tune your car, you'd be looking at anywhere from $500 to$1,000, depending on the engine management system you use. The EZ-EFI tunes itself and will tune for future modifications, whether you bolt on a set of headers or swap in an entirely different engine.

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"Current mass air systems do offer some leeway in regards to modifications, but nowhere near what this system can handle," says Comp Cams Ron Turnpaugh. "We've run it on a 252ci six-cylinder, then on a 350ci small-block, and then on a 570ci big-block without doing anything other than going back through the handheld's wizard and answering the questions. Horsepower ranged from 150 to 659-that's impressive," exclaims Turnpaugh. "This unit uses a wideband sensor, which the OEMs don't. It also stays in closed loop at wide open throttle, which a lot of the OEMs don't do since they can't monitor at that point with a narrow band sensor."

The benefit of running in closed loop at WOT is that you can maintain the target air/fuel ratio correctly. The older systems like the Ford EEC-IV just default to a fuel table that has a fuel curve based off of wide-band testing.

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"If your car made more power, you would lean out," notes Turnpaugh. "You were literally just following an exact amount of preprogrammed fuel. With the wide-band meter that the EZ-EFI uses, you can adjust your air/fuel ratio targets, idle speeds, and acceleration pump fuel tables with the handheld.Also, it is self-tuning. You can change cubic inches, the camshaft, or the heads and just drive on. It will relearn the perfect tune on its own." The EZ-EFI will also adapt to changing fuel octane, but it isn't designed for use with ethanol or methanol fuels.

FAST has run the EZ-EFI on modular engines as well, using its XIM standalone ignition controller to run the coil packs-they've even had it running the new 5.0L Coyote engine. The XIM gives the EZ-EFI the correct tach signal it wants, while reading the stock encoder wheel on the motor.

If there is a drawback to the EZ-EFI system, it's that it isn't recommended for use with power adders. The included MAP sensor is only a 1-bar sensor and can't read the higher pressure, and while that is easy enough to change out for a 2- or 3-bar sensor, the second part of the equation resides in the computer's firmware, which doesn't support that range.

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"The engine can go into boost in many different ways depending on whether it's turbocharged or supercharged," say Turnpaugh. "Boost can be almost immediate on a Roots supercharger, and the system would have absolutely no time to tune before it would go lean. So it was decided it wasn't safe to try to do a self-tuning system for that application."

The EZ-EFI also doesn't control ignition timing, so you couldn't pull timing out when the motor came up on boost either. Nitrous oxide is a different story.

"The reason we [don't advise it] with nitrous oxide is because this system is always in closed loop. If you go to wide-open throttle, it tunes to your WOT air/fuel ratio target that you have set. If you spray nitrous, it doesn't know this, and it will try to keep the air/fuel ratio at the target you have selected for normally aspirated. This is normally too lean for nitrous; it would lean the mixture out to an undesirable point. There are guys running nitrous with it, but they're setting their WOT air/fuel ratio to what they want when the nitrous is on," says Turnpaugh. This will obviously work for the track, and conceivably you could change the tune before you drive home-so it's possible, just not recommended.

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Beyond the EZ-EFI, there is the XFI system. This step is usually chosen if the user wants to have complete control over his tuning, or he wants timing control. Also, it offers the user the safe ability to run power adders. The other situation that would require the XFI upgrade would be if the motor offers too little engine vacuum at idle. FAST has only see one situation like this so far, but when you get down to 9 inches or less, you really need to hand-tune the idle area, and possibly even run in Alpha N mode instead of Speed Density.

To see exactly how the EZ-EFI system works with the multi-port retrofit kit, we summoned up our Street Smart Windsor Mustang project, as it offers a non-stock application that utilizes the factory computer system. The '89 GT in question put down a respectable 300 rwhp and 360 lb-ft of torque when we baselined the car on the TunersInc Dynojet dynamometer. From there, we moved SSW over to the Hurricane Performance shop, where Jason Combs handled the EZ-EFI installation while we took the snaps.

We've used both of these shops on numerous occasions in the past, and they always deliver top quality work in addition to going the distance to satisfy our ridiculous magazine requests. Combs knocked out the install with ease-the most difficult modification was locating the right wire to trigger the fuel pump.

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We took the opportunity while in the shop to try out a couple of tried-and-true bolt-on performance parts that we had in the office before going directly to the EZ-EFI test.

With the EZ-EFI system making the engine management calls, we saw horsepower rise from 317 to 328 at the wheels, and torque increased slightly as well, going from 378 lb-ft to 382. As we outlined earlier in the article, there are many reasons to consider the EZ-EFI system, and if your needs require more, FAST has you covered.

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Old School Power Tricks
Originally for our recent Capri project, this electric fan and pulley set from Latemodel Restoration Supply found its way onto our Street Smart Windsor project as we knew they would produce a healthy bump in power. The aluminum underdrive pulleys (PN ASP-820-125) sell for $104.99, and produced an increase of 8 hp and 11 lb-ft of torque over the factor steel pulleys.

Ditching the stock clutch fan is also a good idea on 5.0L engines, and this budget-friendly electric unit from LRS retails for just $139.99. It comes with its own adjustable thermostat and all of the necessary wiring to install it. The fan (PN PRO-67015) didn't disappoint on the dyno, adding another 8 hp and 7 lb-ft of torque to the Windsor. Tried and true parts that work!