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Background:

For the 2005 season, I used a chassis dyno to tune my primary engine. My engine of choice was a stock 2003 Yamaha R6 with a 6-degree timing advancer and a PowerCommander fuel injection setup. Through the use of the chassis dyno, we had that engine tuned nearly perfect and ran extremely well. I blew this engine (spun a bearing) in August and installed a fresh 2003 Yamaha. Both engines were stock and used a stock 2003 Yamaha CDI (computer). The second engine did not perform well with the primary engine's fuel map. I utilize an Innovate Motorsports LM-1 data acquisition system to monitor oxygen levels in the exhaust and assist in tuning. The second engine would not respond properly to changes in the fuel map. I struggled for the next month trying to tune this engine, but I could not get consistent performance.

The engine would not build proper water temperature and would race at 175 degrees which is too cold for alcohol. Leaning the fuel map did not solve this problem. Finally, for the last race of 2005, I reduced fuel pressure by an unheard of 10psi (go or blow!!!) and the engine ran much better.

Post Season Research:

At the conclusion of the season, I found a website that discusses the function of the PowerCommander. What I found was that the PowerCommander adjusts the fuel injector pulse width (time the injector is spraying) by manipulating the signal from the engine water temperature sensor (sending a 'cool' signal to richen and a 'hot' signal to lean). THATS IT - that is how it works - pretty simple setup!

I found that the engine water temperature sensor in the second engine was not functioning properly at operating temperature. When compared to the sensor installed in my primary engine, it was night and day.

What to Look For:

If you dyno one of these engines you will see a significant power loss (over 10 horsepower) and poor throttle response while the engine is in 'warm-up' mode. Once the engine reaches operating temperature (around 175 degrees) the power comes back and the engine throttle response is crisp. This shows how important the water temperature sender is on these fuel injected engines. Not only will a malfunctioning sensor mess with the PowerCommander, but also the base fuel map within the ECU (engine control unit). If the sensor malfunctions completely - it will put the ECU into a "safe" mode, richen the fuel mixture and absolutely KILL power.

My suggestion is to test your water temperature sender unit for proper operation (buy the Shop Manual for your engine and follow the procedure). Once you find a properly operating sender - treat it like gold. If you dyno tune an engine and get a proper fuel map, but then have to install a different engine and do not have immediate access to the dyno - I would either verify that the sensors in the two engines are operating EXACTLY the same or I would install the sensor from the dyno'ed engine into the second engine.


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	Background: For the 2005 season, I used a chassis dyno to tune my primary engine. My engine of choice was a stock 2003 Yamaha R6 with a 6-degree timing advancer and a PowerCommander fuel injection setup. Through the use of the chassis dyno, we had that engine tuned nearly perfect and ran extremely well. I blew this engine (spun a bearing) in August and installed a fresh 2003 Yamaha. Both engines were stock and used a stock 2003 Yamaha CDI (computer). The second engine did not perform well with the primary engine's fuel map. I utilize an Innovate Motorsports LM-1 data acquisition system to monitor oxygen levels in the exhaust and assist in tuning. The second engine would not respond properly to changes in the fuel map. I struggled for the next month trying to tune this engine, but I could not get consistent performance. The engine would not build proper water temperature and would race at 175 degrees which is too cold for alcohol. Leaning the fuel map did not solve this problem. Finally, for the last race of 2005, I reduced fuel pressure by an unheard of 10psi (go or blow!!!) and the engine ran much better. Post Season Research: At the conclusion of the season, I found a website that discusses the function of the PowerCommander. What I found was that the PowerCommander adjusts the fuel injector pulse width (time the injector is spraying) by manipulating the signal from the engine water temperature sensor (sending a 'cool' signal to richen and a 'hot' signal to lean). THATS IT - that is how it works - pretty simple setup! I found that the engine water temperature sensor in the second engine was not functioning properly at operating temperature. When compared to the sensor installed in my primary engine, it was night and day. What to Look For: If you dyno one of these engines you will see a significant power loss (over 10 horsepower) and poor throttle response while the engine is in 'warm-up' mode. Once the engine reaches operating temperature (around 175 degrees) the power comes back and the engine throttle response is crisp. This shows how important the water temperature sender is on these fuel injected engines. Not only will a malfunctioning sensor mess with the PowerCommander, but also the base fuel map within the ECU (engine control unit). If the sensor malfunctions completely - it will put the ECU into a "safe" mode, richen the fuel mixture and absolutely KILL power. My suggestion is to test your water temperature sender unit for proper operation (buy the Shop Manual for your engine and follow the procedure). Once you find a properly operating sender - treat it like gold. If you dyno tune an engine and get a proper fuel map, but then have to install a different engine and do not have immediate access to the dyno - I would either verify that the sensors in the two engines are operating EXACTLY the same or I would install the sensor from the dyno'ed engine into the second engine.