Over the past few years, we’ve been doing lots of testing of balancing air/fuel ratios, detonation limits, and exhaust temps and found serious horsepower gains to be made with individual cylinder tuning. When tuning an engine, having the proper amount of combustible fuel to the amount of air (air/fuel ratio) to sustain the burn is critical. Running rich can cause a loss in power, while running too lean may result in serious engine damage.
In testing, we acquired AEM’s newest 4-Channel Wideband UEGO Controller that allows users to monitor the air/fuel ratio (AFR) of up to four individual cylinders simultaneously, along with an AEM Programmable “Series 2” Engine Management System to test and tune on our test subject, the Evasive Motorsports S2000.
Monitoring individual air/fuel ratio measurements doesn’t just help tuning fuel per cylinder, it can also lead to improvements in your intake/exhaust system design to run more efficiently and with greater horsepower potential. This was the case in many engines, including the S2000 F20/F22C engine.
With our AEM products along with some proficient tuning, we were confident we would be able to extract additional horsepower out of an engine that’s built a reputation of offering marginal power gains when gifted with additional bolt-on performance parts.
Prior to installing the AEM products, the S2000 was already equipped with a Toda header, J’s Racing intake, EVS custom 70mm titanium exhaust and a mail-in reflash ECU, which combined to deliver 220 whp.
Although the S2000 might not have the big horsepower numbers that we’d/you’d like to see (if even just for bragging rights), this Honda has built a reputation in the S2000 community as well as the time-attack circuit. The S2000 prior to our testing currently holds the record in the Street RWD class with an official 2010 SLB lap time of 1:56.7 at Button Willow Raceway.
AEM 4-Channel Wideband UEGO
Typically, differences in air/fuel ratio between cylinders vary depending on throttle loads/engine speeds. AEM’s 4-Channel Wideband UEGO Controller allows users to monitor the air/fuel ratio (AFR) of up to four individual cylinders simultaneously (or up to 12 cylinders if multiple units are paired together). The 4-Channel Wideband UEGO controller is ideal for anyone using an engine management system or data logger to monitor individual cylinder AFR in an effort to maximize engine power where individual cylinder trims are needed. The 4-Channel UEGO amp quickly and easily allows for four lambda sensors to be installed in a motor, and allows information to be transmitted via analog inputs or CAN to your ECU or data logger. The kit has both 0-5V and CAN outputs for integration with any engine management or data system, and features optional exhaust backpressure compensation. The unit features a shock and weatherproof housing, allowing it to be mounted virtually anywhere in the vehicle without worry.
Stainless steel bungs, specially designed for use in individual port applications, feature a finned design to reduce sensor body temperature and minimize exhaust port restriction. The bung is specifically designed so the sensor can provide accurate AFR readings with minimal flow intrusion and survive extreme exhaust gas temperatures.
The Bosch 4.2LSU UEGO sensors are factory calibrated and never require free air calibration. Free air calibration requires the sensor to sit in free-air, heated for at least two minutes, and most importantly maintaining consistent battery voltage. Each Bosch sensor is accurate to 0.1 AFR for precision tuning. The special design of the sensors offers low restriction exhaust ports to allow minimal impedance of flow.
To begin modifications, we properly secured our Toda header to the workbench before taking proper measurements to begin drilling holes for the bungs.
When mounting the sensor bungs, the sensor tip must be exposed to exhaust gas in order to give accurate AFR readings and be mounted at an angle of at least 10 degrees from horizontal in order to prevent liquids from collecting in the sensor housing. AEM also offers an optional EBP (exhaust backpressure) kit (PN 30-2064) that must be used if you have bought the AEM 4-Channel Wideband UEGO and plan to install it between the engine and the turbo. You will need to use this pressure sensor to get an accurate air/fuel reading. As pressure changes at the sensor, the air/fuel readings will change resulting in an incorrect tune.
For thin-wall header tubing, drill a 15⁄16-inch hole and weld in the bung. For thick-wall tubing/castings, drill a 11⁄16-inch hole and weld in the bung.
Be sure to use a metal file to clean up any sharp edges or burrs on both the outside and inside of the tubing before you begin welding.
AEM Wideband UEGO Gauge
The wideband UEGO sensor controller accurately monitors air/fuel ratios (AFR) during the tuning process to prevent a lean fuel mixture, which could lead to engine damage. AEM has combined its single-channel wideband UEGO controller and gauge display into one unit, offering AFR accuracy and control with an easy-to-read interface.
AEM’s Wideband UEGO Controller features a digital LED display and sweeping LED “needle” that changes colors as AFR changes from rich to lean. The UEGO gauge proved beneficial when tuning the S2000 and was requested by our tuner to help properly monitor the engine’s AFR while making full throttle passes on the dyno.
Okada Project Plasma Direct Coil Packs
Okada Project Plasma Direct coil packs use a high-power amplifier built into the unit to increase spark current by two times that of the original equipment. The Okada Project coil packs replaced our factory ignition coil system to increase ignition output and supply greater combustion efficiency—two important features we deemed necessary as we attempt to squeeze every last bit of power out of our 2.2L engine.
AEM Programmable “Series 2” Engine Management System
The AEM EMS has come a long way since its first debut in the tuner market. The “Series 2” engine management system for the ’06-08 AP2 S2000, which uses a drive-by-wire system, is a complete engine control system that plugs into the factory harness and uses the factory sensors. This means you do not need to replace any part of the harness or sensors, just plug the EMS into the harness and begin tuning. The Series 2 EMS is fully programmable as it allows you to control every aspect of your 2.2L engine including selectable direct drive or 0-5V coil output for custom applications. From VTEC to rev limit, timing, ignition control, injector size compensation, boost control, built-in/real-time data logging capability, nitrous injection, even anti-lag and individual cylinder fuel and timing—which was the main focus for our test.
AEMdata is a custom data analysis software package with advanced 3-D graphics and a user-friendly interface. The software is integrated in a number of AEM products including the EMS Series 2. AEMdata allows the user to review data, playback data, and overlay data using charts, dash displays, gauges, or custom displays that you create. High-speed logging is saved to a file internally or via PC connection. AEMdata logs each channel and allows you to overlay the data on a track map to know exactly what your car was doing.
Features include custom math channels, X/Y plots and histograms, stage or circuit modes, and more, all aimed at making sure you get the most out of your data.
AEMdata features a functional workspace that allows information to be quickly accessed. It is designed to be customizable by the user with either a layout interface or gauge-style setup.
Vehicles equipped with a Vehicle Speed Sensor (VSS) and accelerometer can log data to create track maps and overlay their information from previous runs to monitor performance.
MP Tuning offers a custom extended wire harness for the S2000 AEM EMS to make installation a simple plug-and-play process.
Mitch Pederson of MP Tuning, a former AEM engineer, who was part of a team responsible for developing the EMS fuel management system, made the necessary modifications to our AEM unit and played a key part in tuning our S2000.
This screenshot shows the UEGO system monitoring air/fuel ratios for each cylinder. This allows Pederson to carefully calibrate the cylinders individually for optimal performance.
With a baseline of 220.4 and 151.9 lb ft of torque, Pederson altered timing, fuel, and ignition, using the provided AEM basemap to reveal consistent gains of 5 hp and 4 lb-ft of torque from 6,000 rpm to redline. The vehicle’s redline was also increased from 8,000 to 8,500 rpm over factory.
We spent extra time tuning within the midrange powerband, focusing on improving the VTEC transition from the low to high cam phase. Dyno charts revealed a noticeable increase in midrange power and torque, with additional tuning. The S2000 recorded the largest gain at 4,950 rpm with gains of 17 hp and 16 lb-ft of torque over baseline.