K.J. Jones
March 1, 2008
The needle of Innovate Technology's G2 air/fuel gauge (PN 3801; $289 kit/PN 3803; $99 gauge only) is locked in at 14.7 (stoicheometric) air/fuel, shortly after installation in a blown Two-Valve Mustang GT. Monitoring air/fuel values with this type of gauge ensures an engine's air/fuel mixture is optimal for achieving maximum efficiency and performance during normal operation and when the engine is being tuned.

We're going to (hopefully safely) assume that Mustang enthusiasts who follow our tech content on a regular basis are familiar with the term air/fuel ratio by now, as it's something we often discuss when projects involve tuning an engine on the dyno. Don't worry-there won't be a quiz at the end of this report, but before we go further, it's important that we give a layman's definition of what an engine's A/F ratio is for those who may have wondered for a long time but were afraid to ask.

Correct air/fuel levels for almost all 5.0, 4.6, and 5.4 EFI engines in late-model Mustangs are dependent on oxygen sensors, which measure the composition of the engine's exhaust gas. The data output of each sensor is processed by the PCM, which then triggers the fuel injectors to disperse the correct volume of fuel into the intake stream

So, for the uninitiated, air/fuel is the ratio between air's mass and fuel's mass in the mixture of the two elements inside a 'Stang's engine. The ratio is a major contributor to the combustion process and ultimately to the engine's efficiency at idle and wide-open throttle.

The G2 air/fuel gauge kit includes this LC-1 Lambda Cable wideband controller. It features analog input/output serial connectors that allow for adding/networking other Innovate modular tuning system components-such as the popular LM-1 or a DL-32 datalogger-and downloading the captured information directly into a laptop for review.

Air/fuel does have a point of perfection, so to speak. The zen point of 14.7 A/F is called the stoichiometric mixture. It's the precise amount of oxygen atoms necessary to completely burn fuel in an air/fuel mixture while the engine is idling. Ratios lower than 14.7 are con-sidered rich. On the other hand, when A/F numbers are greater than stoich, a mixture is referred to as lean. Rich and lean air/fuel mixtures produce less power and fuel efficiency than the stoichiometric mixture.

For most stock, naturally aspirated Mustangs, knowledge or awareness of the engine's normal air/fuel ratio (12.5-13.3) and what the O2 sensors are reading isn't really necessary, as the PCM does a fine job of handling any changes that warrant adjustment in the engine's tune. The need to know exactly what the A/F ratio is becomes more important when a 'Stang's game is stepped up with the addition of high-performance bolt-ons (heads, cams, cold-air intake, exhaust), a power adder (11.3-12.1), and once the dyno and tuning software are used to dial-in maximum performance for a combination.

After safely lifting the 'Stang on a twin-post hoist (of course, this process includes disconnecting the negative battery cable first), Saul drills a 7/8-inch hole in the passenger-side tube of the X-shape crossover and welds Innovate's stainless steel bung in place. Once the bung cools, the G2 kit's wideband oxygen sensor is threaded into place and secured with a 22mm wrench. Coating the sensor's threads with a dab of antiseize is recommended.

The best way to monitor air/fuel ratio (other than via the oxygen sensor on a dyno) is by using a wideband oxygen sensor and a good air/fuel gauge. In this exercise, we're installing and checking out the fit and function of the latest air/fuel ratio gauge by Innovate Technology. The company's new G2 gauge kit (PN 3801; $289) is highlighted by a stylish silver, 2 1/16-inch analog A/F gauge.

The gauge itself boasts a high-speed stepper motor for quick, smooth sweeps across the dial, as well as through-dial backlighting and an illuminated pointer for easy at-a-glance reading in darker light. The package we're testing also features a wideband oxygen sensor, an LC-1 Lambda Cable wideband controller, and Innovate's LogWorks 2.0 engine-tuning software

Here are the highlights of a recent Innovate G2 installation we witnessed. Extreme Automotive's Saul "The Surgeon" Gutierrez handled the setup chores on an '04 GT, sporting an aftercooled Vortech S-Trim, as well as SLP long-tube headers and exhaust.

Naturally, all the upgrades have an effect on WOT air/fuel, but the supercharger's boost (or boost of a turbocharger or nitrous shot, for that matter) creates the biggest need for keeping a close eye on air/fuel info. Check it!

Most tuners and hard-core Mustang racers consider wideband oxygen sensors must-have tools for collecting data that's crucial to perfecting an engine's tune.

Widebands provide a precise indication of the exact air/fuel ratios across a broad range, as they're capable of compensating for changes in temperature, altitude, and even the condition of the sensor itself

By contrast, the output of a narrowband O2 more closely resembles an approximate relationship to an engine's true A/F mixture.

Wideband oxygen sensors alone can be expensive, so Innovate's total package (A/F gauge, O2 sensor, and Lambda Cable controller) is a good deal if you upgrade to a turbo, blower, or nitrous or want to tune any combo for max performance.