IF YOU DON’T KNOW, NOW YOU KNOW

Tribal knowledge can be both an incredible strength and a crippling weakness. As human beings, we grow accustomed to familiarity, and when we work and play with like-minded people who share our passions, shared knowledge is assumed. But what about the newcomers who want to be a part of what we do?

Sometimes it’s just good to get back to basics and share knowledge verbally and through instruction, and in doing so promote the growth of our industry, hobby, and passion. That’s why this article is worth the read whether you know all about widebands or not. If you are new, we cover the basics, and if you are seasoned, consider this a refresher on how to explain a wideband to your friend who is new to performance or your customer if you are a shop. You may even pick up a couple of new nuggets of info along the way!

WHAT IS A WIDEBAND UEGO AIR/FUEL CONTROLLER?

AEM's Wideband UEGO (Universal Exhaust Gas Oxygen, pronounced “You-Way-Go”) Controllers are powerful, cost-effective tuning tools that allow users to accurately monitor the Air/Fuel Ratio (AFR) of their engine.

WHY USE A WIDEBAND AIR/FUEL CONTROLLER?

Accurate AFR data is critical when tuning an engine. Running rich (very low air/fuel ratio, excessive fuel) can cause a loss in power, while running too lean (very high air/fuel ratio, not enough fuel) may result in serious engine damage. Using a wideband air/fuel controller during the tuning process allows you to monitor AFR and adjust tuning parameters to optimize them for maximum power and efficiency.

WHAT PURPOSE DOES A WIDEBAND SERVE?

Determine the optimum efficiency of an engine (more efficiency means more power)

Prevent lean conditions which lead to detonation and possible engine damage

Use as an input with a standalone ECU for closed-loop feedback tuning

AFR can be recorded at the collector to get an average AFR across all cylinders, on each back of a V-engine for bank-to-bank averages, or in each individual cylinder. This diagram outlines how to get individual cylinder AFR on a V8 using X-Series inline wideband controllers. All 8 controllers report AFR data to the CD Carbon logging dash over a 2-wire CAN bus connection. This data can be sent to any standalone ECU that accepts 3rd party CAN data.

IS A WIDEBAND USEFUL FOR TUNING CARBURETORS?

The short answer is yes!

• Use a gauge-type controller to view AFR and adjust based on steady-state readout
• Output AFR data to a datalogger to review and make changes
• A critical tool for making jetting adjustments at the track when racing at different altitudes

WHAT IS RESPONSE TIME AND WHY DOES IT MATTER?

Deadtime is the delay between when exhaust gas composition changes and when that change is reported by the O2 sensor. While flow of exhaust gases (transport delay) can affect deadtime, the sensing elements response to the gas is the largest contributor to deadtime when an engine is in high RPM under load. With long deadtimes, whatever changes you make to the base fueling will likely be in the wrong location. Reducing deadtime improves wideband feedback control, and can provide a safer, more powerful, and accurate tune.

WHAT TYPES OF SENSORS ARE THERE AND ARE THEY BASCIALLY THE SAME?

There are three primary types of UEGO sensors being used in the performance market, NTK, Bosch 4.2LSU and Bosch 4.9LSU. AEM wideband UEGO controllers use the Bosch 4.9LSU, and AEM’s internal Lambda controllers in its Infinity ECUs, and its legacy 4Channel Wideband Controller and original 30-4100 wideband gauge use the Bosch 4.2LSU.

• NTK: Very durable, slow responding
• Bosch 4.2LSU: Durable, faster responding than NTK
• Bosch 4.9LSU: Less durable, faster response than 4.2 and faster light off time

HOW LONG WILL A SENSOR TYPICALLY LAST?

The life of a sensor is determined by several factors. In racing, these sensors live in environments generally designed to kill them.

• 2-Step events
• Hard-cut rev limiters
• Leaded racing fuels

Other common killers include:

• Improper installation (wrong wrench, wrong angle)
• Modifying the harness
• Allowing the sensor to heat before starting engine
• Physical shock damage (it’s ceramic)

WHAT IS LAMBDA? WHY WOULD I USE IT?

Lambda readings are the amount of oxygen present in the combustion chamber regardless of fuel type, so it is a great tuning tool for vehicles using alternative fuels. Conversion charts are available online.

WHAT IS FREE-AIR CALIBRATION? IS IT BETTER OR MORE ACCURATE?

Free-air calibration is a tedious process for calibrating a UEGO sensor. The sensor must be removed from the bung and introduced to ‘free-air’ during a calibration process and requires repeated calibration.

In our experience, using a factory-calibrated sensor leads to better overall accuracy in both the short and long term. However, we understand that there may be instances, like in the middle of an event, when it may be necessary to free-air calibrate a sensor until a new one is installed, which is why AEM’s X-Series wideband AFR controller gauges allow you to use a sensor’s factory calibration, or free-air calibrate a sensor.

We hope that this information answered a few questions and provided some talking points for you when discussing wideband air/fuel ratio controllers with your friends or customers. Do you have more questions? Give us a call or send us an email, we are here to help!