Justin Fivella
June 19, 2013

A lot goes through your mind as you near the end of the quarter-mile with your expensive motor howling at redline. "What's my air/fuel ratio?" "How much boost am I making?" "How high is the engine revving?"

Such thoughts entered our minds as we crossed the stripe at Sacramento Raceway in our newly built smog-legal coupe. Sadly, we had no answers. Why? Because we had nothing more than factory Ford gauges—and that's a serious problem when you have a new supercharged engine that you want to keep alive.

We're making big power while staying emissions friendly with our smog-legal-coupe project LX, and after an SCT chip tune from Kurgan Motorsports last issue, it made 512 hp and 550 lb-ft on 91-octane pump gas. Those dyno numbers were achieved with a catted X-style mid-pipe and spinning the smog pump, and the stock mechanical fan.

The AEM Wideband Failsafe gauge comes with everything needed to monitor boost/vacuum, the air/fuel ratio, and even has a failsafe feature that can save your motor should it lean out.

We also paid a visit to Sacramento Raceway, but a worn differential made traction nonexistent in the lower gears, and the old T5 and stock axles prevented hard launches. While we managed to break into the 11s with an 11.99 at 121 mph, we hadn't unlocked all the performance.

With that, we paid a visit to Stanton Performance in Martinez, California, and together with owner Jeremy Stanton, we made a list of the coupe's shortcomings that quickly grew from an inch to a mile. Its drivetrain and suspension flaws were glaring, but before diving into the chassis, there were smaller mods that should net huge improvements.

Protecting The Investment

Lets be honest, driving a forced-induction car without quality gauges is like playing Russian roulette. Monitoring engine vitals is crucial since a tuned motor can grenade in a heartbeat if a lean condition occurs. Although there's big business under the hood of our coupe, we didn't want the rest of the car to snitch off what lies beneath. Why, because there's nothing cooler than a sleeper. So we decided to install AEM Electronics combination boost and wideband gauge. But when we also discovered the high-tech gauge had a failsafe feature, we struck gold.

"Our Wideband Failsafe gauge comes with a built-in failsafe feature that can be programmed to activate various things that can save a motor when the AFR moves outside a preset window," said Lawson Molica of AEM. "If the AFR reaches outside the safe zone (lean or rich), the failsafe can be set to trigger something as simple as a check-engine and shift light, or if you prefer something more concrete, it can be set to pull ignition timing or open the wastegate on a forced-induction application."

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Chew on that for a second. For those who prefer a soft slap on the wrist, the failsafe can be set to illuminate your Check Engine light that will remind you to chop throttle. The failsafe can also open a wastegate to bleed boost, activate an alternative fuel map, cut the ignition coil, or even trigger the ECU or an MSD to pull timing.

The included AEM software is simple and the failsafe feature is highly adjustable. Users can set the length of time the a/f ratio is allowed outside the safe limits before registering the failsafe. You can prevent false triggers from spikes by programming a time delay. With the delay, the failsafe is only activated after the set a/f ratio has exceeded the safe boundaries for a set amount of time. The failsafe can also be activated based on a/f ratio against vacuum or boost. Monitoring the tune in relation to boost or vacuum helps prevent false triggers during city driving where on/off throttle applications can cause significant a/f changes.

"The software allows the user to set a wide a/f window at low vacuum or boost levels where a/f ratios aren't as important (say from 15.0:1 to 9.0:1) and then tighten the zones at which the failsafe will be triggered (say, 11.0:1 to 12.5:1) where it's most important, as the revs or boost rise," Molica said. (See 5 for an illustration that further explains this feature.)