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2014 Mazda5 Sport: Tom's Hardware's Project Car Update

ECU Tuning With Tactrix OpenPort, MazdaEdit And Orange Virus Tuning

Modern engine optimization is different than tuning carburetors back in the muscle car days. Whereas you'd previously make physical adjustments to the air/fuel ratio, manipulating mixtures and altering timing can be achieved by plugging in your laptop, changing a file, and uploading to the vehicle's ECU. Connecting a PC requires a special cable that plugs into the OBD-II port, though.

The options for tuning a standard Mazda are limited, so we went to Tactrix, a San Francisco-based company, for a compatible interface. Its Openport 2.0 cable works with a variety of vehicles and software, including Mitsubishi Lancer Evolutions and a number of Subarus. This isn't just a simple USB-to-OBD-II interface, either. There's a simple ARM7TDMI SoC inside running at 72MHz, which controls communication. It's purportedly compatible with virtually every OBD-II protocol in use, including the ISO 9141, CAN and J1850 standards. A microSD slot even allows you to log vehicle information. Unfortunately, our tuning software doesn't let us exploit that feature.

We’re working with Mat Wilson at Orange Virus Tuning to squeeze out more performance from the 2.5L four-cylinder motor in our Mazda5. Since Mat tunes the ECU using MazdaEdit through the Openport 2.0, that's the application in play today.

MazdaEdit is a tuning application developed by epifan Software. It supports most Mazda vehicles, including the Mazdaspeed3/6, CX-7, MPV, 3, 6, Miata, RX-8, 2 and CX-5. The company also sells ecuEdit, which accommodates Mitsubishi Lancer Evolutions, Subaru Impreza WRXs, Foresters and Legacys, in addition to brzEdit (for Subaru's BRZ and the Scion FR-S), along with gtr35Edit, supporting the amazing Nissan GT-R.

Before we could get the project car tuned, we needed baseline performance numbers. For that purpose, we enlisted the help of Bob “De janitor” Roberts, formerly of PC Arena and CNET Asia, owner of Drift Office in Auburn, Washington, and a friend of mine (and many other current and former Tom’s Hardware writers). Bob graciously let us use the Drift Office dynamometer to benchmark the little 2.5L engine's output.

Unfortunately, the tuning process takes time, and we were only able to get baseline performance numbers for the car. The ambient temperature was 59°F with 77% humidity at an elevation of 62 feet above sea level. We started with a jogging run to make sure everything was hooked up correctly, followed by two runs in third gear to collect the performance data.

Our best run revealed that the 2.5L MZR puts out 154hp and 161lb-ft of torque at the wheels on the Dynojet dyno. Mazda rates the 5 at 157hp and 163lb-ft at the crank, which of course is surprising since our numbers don’t show much power loss through the drivetrain. In addition, the power curve looks fairly smooth with the exception of a dip at 4500RPM, where the ECU goes from closed-loop to open-loop to improve fuel economy.