For nearly four decades, AEM has been on a mission to make advanced motorsport technologies accessible to the wider high-performance community. Along with innovations like the development of the aftermarket’s first standalone engine management system to offer direct plug-and-play compatibility with a vehicle’s OE wiring harness, AEM also became a pioneer in wideband air/fuel ratio gauges, combining the accuracy and response times that enthusiasts and racers need at an affordable price point. And as AEM’s Sam Chaysavang explains, that desire to create products which help maximize performance for street and motorsport applications alike continues to drive the company’s development efforts today.
“We were the first to offer a wideband product that was also a gauge – prior to that, the wideband controller products on the market were really niche and mainly built for professionals who were developing engine calibrations. And as a result, they weren’t really affordable for the average user; they were specialty equipment for tuners and designed to be used as a tool to help them do their jobs. But we realized that end users could also benefit from having a low-cost, accurate, and fast-responding wideband system that allowed them to monitor the air/fuel ratios within their engines.”
The result was the AEM’s Classic Digital Wideband Kit, a system which has evolved over time to incorporate more advanced sensor technology, yet still maintains its original design ethos today.
“The original wideband gauge supported the Bosch LSU 4.2 wideband sensor,” he says. “There are a number of wideband sensor manufacturers out there, but Bosch is a large OEM supplier, and we found that their sensor technology was top tier. We just needed a way to control it and display the information, and that’s where the Classic digital gauge came in. And with our background in engine management technology, we understood how useful wideband could be as a tuning tool, so we also integrated outputs for 0-5v analog as well as serial.”
Some might assume that wideband gauges are really only needed for engine combinations that involve serious amounts of boost, Chaysavang is quick to point out that their usefulness is much broader than that.
“I’ve had customers without wideband gauges come to me and say, ‘My car feels weird.’ And then you have to figure out what the problem is before you can even start on a solution. But if someone with a wideband comes to me and says that, I can just look at it and see that it says 16:1 AFR, for example. At that point we know the car is running lean and we can look at the data to pinpoint where the calibration needs adjustment, or determine if something else is going on with the car. Having an improper air/fuel ratio is going affect performance and reliability of any engine, whether it’s forced induction or naturally aspirated. Even in a naturally aspirated engine combination we have to deliver the proper amount of fuel to match the amount of air that the engine is consuming. And without AFR information, you just don’t know if you’re actually doing that.”
Chaysavang says that for the vast majority of enthusiasts, wideband gauges are about peace of mind more than anything else. With the ability to monitor the engine’s air/fuel ratio in real time, small issues can be quickly identified before they become bigger ones, and that means that the accuracy and response time of the device play crucial roles in its usefulness.
With that in mind, AEM established another milestone in the wideband game a few years later when they incorporated the Bosch LSU 4.9 sensor into the design of the Classic Digital Wideband UEGO gauge. “We were the first company to support that sensor, and I think we set a new standard with that.”
The Bosch LSU 4.9 sensor offered faster response time as compared to the 4.2 while retaining the same fuel compatibility characteristics. “These differences in response time might not be a game changer for someone who is just monitoring their AFR; not many people are going to visually notice the difference between a 100-millisecond delay and a 20-millisecond delay,” Chaysavang points out. “But when you’re getting into the nitty gritty as a tuner, it can be extremely valuable when you’re dealing with transient fueling. You’re looking at quick changes in throttle inputs, and being able to see how the AFR responds on a level this granular can help inform the tuning strategy and give you greater insight into what will refine the calibration further and improve that throttle response. If you don’t have response time at this level, there’s a lot more assumption and guessing involved because you’re not getting the complete picture. I’ve seen some wideband sensors completely miss a cylinder misfire, but with ours, you’ll catch it as a quick spike in the air/fuel ratio.”
While wideband gauges provide enthusiasts with peace of mind, in a motorsport setting they can mean the difference between a quick tweak during a practice session and a very costly DNF on race day.
“Obviously racers want to ensure that the engine is running as efficiently as possible to stay ahead of the competition, and having AFR information from a wideband gauge allows you to take the steps needed to tune the car properly before the race,” Chaysavang says.
“And beyond that, it can also play a role in strategy, and how you drive the car during the race. If you’re out testing and you notice that the engine isn’t running right because the carburetor was dialed in at sea level, and now you’re at 10,000 ft of elevation, the air/fuel ratio is going to provide that information. Then you’ll know that something isn’t right and be able to back off of it so you don’t kill the motor during practice, and you can then dial in the car ahead of the race. And when you’re actually in the race, that gauge can help you decide whether to keep pushing or not. If the engine isn’t running right at the beginning of the race and gauge is letting you know that, you might be able to pit and address the issue. But if it’s the last lap of the race and you’re battling for a podium, you might just want to stay in it if things don’t look too bad on the gauge.”
This is also where AEM’s X-Series Wideband UEGO AFR Gauge Kit can really come in handy.
“This is our premium line of gauges, which offer a larger display area in a really compact form factor, along with the fastest response time on the market,” says Chaysavang. “This gauge was recently updated with a new sensor that we co-developed with a company called FAE to essentially out-do the Bosch 4.9 sensor, the latter of which is already the current industry standard. And we feel that this new sensor is going to revolutionize the wideband market.”
While the FAE sensor offers 10% faster response time as compared to the Bosch 4.9 sensor, he cites durability as the main driver for the new sensor’s development.
“The Achilles Heel of the Bosch 4.9 sensor has always been its robustness in harsh environments. And in a motorsport application where you might be using leaded fuel and running for hours at a time on full boil, the 4.9 sensors typically don’t live very long. So we developed a sensor with FAE that offers three times the longevity of the Bosch 4.9 as well as that faster response. For racers, that basically equates to the accuracy of a Bosch LSU 4.9 sensor paired with the robustness of the old Bosch LSU 4.2 sensor.”
AEM’s X-Series Wideband UEGO AFR gauge remains compatible with both the new FAE sensor as well as Bosch LSU 4.9 sensor. Chaysavang notes that both FAE and Bosch sensors are equipped with a laser-calibrated resistor on the sensor connector that provides calibration information to the gauge. This means that free air sensor calibration is never required, but calibration can be done that way if the end user chooses to do so.
“A lot of our competitors like to claim that you can’t get an accurate air/fuel ratio measurement unless you have a measured ‘control,’ and they so they do this free air calibration process where they take the sensor out and expose it to free air. That measurement gives it the ‘0’ value, and from there the air/fuel ratio is measured based off of that. There’s a misconception that design of our gauge won’t allow for free air calibration, but that’s not the case. We support both methods – you can do the free air calibration, or you can do the resistor calibration. As a tuner, I’m not a big fan of free air calibration because the laser calibration is done by the factory and it’s always going to be the same. At the end of the day, you give the engine what it likes – you’re not aiming for a specific number. Free air calibration also presents more opportunity for someone to make a mistake during that calibration process, and then the tuner is relying on a calibration that may or may not be accurate. With a factory laser calibration, that just isn’t an issue.”
He adds that the key to getting the most out of an AEM Wideband UEGO gauge kit is simply to follow the installation instructions as closely as possible.
Shop AEM X-Series Wideband UEGO AFR Gauge Kit here.
“If you ignore those, you will likely reduce sensor life. We see a lot of situations where people have installed the sensor in the exhaust pipe at an improper angle, or too close from the exhaust ports, or too far away from them. All of those variables matter, so follow the instructions to a T to get the best results and the longest sensor life possible.”
And for those who might feel like this is unnecessary addition to their build, he offers an inarguable fact.
“I’ve had a lot of customers ask, ‘Do I really need that sensor? Do I really need that gauge?’ And I always tell them the same thing: A wideband gauge is cheaper than an engine. Two hundred bucks is a small price to pay for the peace of mind that comes from knowing what’s going on with your engine. It’s worth every penny.”
