Initial Setup of the Pro Control Unit

It is best to start your adjustments from low speeds, placing extra load on the engine by adding weight or using a larger propeller.

There are several ways one can go about fine tuning the Pro Control Unit, however the procedure is ultimately the same. The method involves starting at a broad, rich fuel setting and carefully leaning down the mixture across the RPM range of the engine. We started our testing with a baseline 2.5-liter 260 horsepower fuel curve that was provided as the default setting by Brucato Machine and Tool.

Since the PCU offers the ability to adjust the fuel mixture for each RPM range, we wanted to run the engine throughout the entire RPM range, up to wide open throttle, adjusting each specific encoder in small increments. It is important to fine tune your engine while under greater than normal load (adding passengers to the boat, etc.). The loaded condition will highlight lean and rich conditions and allow for easier adjustments.

Before you begin, it is important that you note engine performance very carefully with the Mercury ECU installed. Take a notepad aboard and have a passenger record the exhaust gas temperature readings at all RPM ranges. Always be sure that the boat, as well as the driver and passenger are equipped with the proper safety equipment at all times.

We started by setting the Brucato Steamwheel to a plus-20 percent rich setting. For those of you that do not have the Steamwheel, you will want to make this adjustment to the Main knob inside the PCU itself. It is very important to start out with these settings, since this would help avoid any lean conditions during initial setup.

Left to Right 1. Brucato Steamwheel located within easy reach of both driver and passenger. 2. PCU secured to boat floor with cover removed; plugged into extension harness. 3. It's a good idea to photocopy the encoder layout and tape it to the interior of the boat during testing. 4. Adjusting the Brucato Steamwheel during testing.

We began our PCU setup by adjusting the idle mixture, then slowly worked our way up the RPM range, carefully monitoring EGT readings and engine performance based on the performance of our Mercury ECU. We tested launches, sustained cruising speeds, and acceleration from midrange speeds – gradually leaning down the mixture in the RPM ranges that needed adjustment.

Start your tuning from idle adjustments and slowly work your way up the RPM range.  Repeat a slow throttle sweep across the adjusted ranges.

It is important to remember that slow and careful adjustments are the key to accuracy. We adjusted in 1% increments, paying careful attention to engine performance under a variety of loads at each given RPM point. Start out by monitoring engine performance throughout a 2000 RPM range, and then work your way in for a fine tune, adjusting the appropriate PCU encoder knobs. When that particular RPM range is adjusted, move on to another RPM block. For example, after the 500-2000 RPM band was fully tuned, we monitored the RPM range from 2000-4000 RPM. We made broad adjustments for good performance, and then we isolated smaller RPM ranges within the 2000-4000 segment and adjusted the mixture. 

Take your time when you narrow down your adjustments, and cycle the engine several times through the adjusted RPM ranges to be sure of a good tune.   The Brucato PCU can also be interfaced with a personal computer via a optional serial data cable.  Using an enhanced version of the Windows Hyper Terminal (included with the PCU data cable), you can view and change your fuel curve adjustments, rev limiter, and view engine operating parameters such as peripheral sensor data.  You can interface a notebook computer with the PCU while the engine is off or operating at idle speeds, or simply plug in the Brucato AC adapter (also included with the PCU data cable) to the PCU harness and you can make adjustments anywhere. 

Although the PCU data cable and a computer is not needed to fully exploit the PCU's technical abilities, it can help give you a more complete understanding of your tuning progress.  Also, the PCU data interface is needed to set the maximum rev limit.  It's an option worth considering if you're planning on making a lot of adjustments to the PCU during the course of a boating or race season.

Page Three: Testing The Pro Control Unit