What is a Baro Sensor and why would I want or need one?
The EFI systems on Buell XB motorcycles rely on a narrow band O2 sensor signal to maintain a specific measured air fuel ratio (AFR) during cruise riding. This is necessary to meet emissions standards and provide optimum efficiency. As these bikes age and get modified, the data provided by the O2 sensor becomes less accurate and/or usable. The sensors get dirty, rings and seals wear allowing some oil to be burned, performance mods are made, etc, etc. Very often, the ECM begins to sense a RICH condition and reacts by LEANING out (decreasing) the fuel delivery unnecessarily. It is a gradual process that will often go unnoticed until the bike starts to run very poorly, overheats, or you connect and view certain settings using Ecmdroid or tuning software. If it's not resolved it can lead to serious engine damage.
What can be done?
As explained in the AFV tutorial here, you can set and lock a desired Adaptive Fuel Value (AFV) setting, or you can turn off the "closed loop" (O2 sensing) feature entirely. This way, the fuel scheduling is based entirely on the maps and temperature compensation settings in the ECM and not adjusted for data provided by a very restrictive and unreliable narrow band O2 sensor. You may have heard the term "running open loop" from racers or performance minded people who have disabled or completely removed the O2 sensors from their car or motorcycle. This is because the primary purpose of a narrow band O2 sensor is to meet emissions and efficiency requirements.
Altitude Factors
The negative side effect of preventing the ECM from lowering the AFV on an XB is noticed when the bike is ridden in areas of significantly different altitude then what the bike was tuned at. The only way the ECM could compensate for altitude changes was based on data from the O2 sensor. As the altitude increased, the AFV was decreased and vice-versa. This is not the optimum method, but it's the way the bikes came from the factory.
Baro Compensation
On most modern EFI systems atmospheric and/or manifold pressure sensing is also used to calculate fuel delivery. This way, a vehicle operating at 10,000 feet above sea level should have the same AFR as one at sea level. Fortunately for XB owners, the baro sensing capability is built into the ECMs, it was just never utilized until they were used on the 1125 models. This Baro Sensor Kit (along with the necessary changes to the ECM settings) allows XB owners to take advantage of this feature with ease. To install, simply plug the sensor in to the exhaust valve connector under your seat and connect the ground wire to the negative battery terminal or frame. Then, install the provided EEPROM file and you're done! Now you can set your bike up for optimum performance WITH continuous compensation for altitude changes.
Now You Have Options
Once the Baro feature is activated you have various options that can be easily configured using Ecmdroid is seconds.
Option 1 - Keep the O2 sensing settings stock with the ADDITION of Baro compensation. This way you still have the closed loop function with baro sensing that provides a constant and more accurate adjustment for altitude change.
Option 2 - Set an optimum minumum AFV of ~100, with closed loop and Baro enabled. In this mode the ECM can add fuel for a sensed lean condition that may be caused by an intake leak or fuel delivery problem, and reduce fuel delivery (Baro compensation) at higher altitudes. The ECM can not lower the AFV less than the minimum setting.
Option 3 - Disable closed loop with Baro enabled. Only temperature and Baro compensations are used. Any mechanical issues with the bike will not be "masked" by the ECM.
An EEPROM file will be sent to you configured with the options desired. These can be easily changed using Ecmdroid without any tuning or EFI expertise. Remember, you can always go back to your saved original file if necessary.
What bikes can this kit be used on?
All XB models with 2004+ stock or "Race Use Only" ECMs installed. 2003 models can use ECMs from 2004 - 2007, otherwise known as DDFI2 ECMs, that have BUEGB or BUEIB firmware. For ECM availability email us here. On 2008+ models there is an additional step that is easily accomplished without the use of any tools.
Where do I get the modified EEPROM file?
It is included with the kit. Simply save your original file as explained here and email it to info@buelltooth.com. It will be returned with the necessary changes.
I have an aftermarket exhaust and K&N filter installed but I haven't had the bike tuned. Will this make it run correctly?
No. This is not a replacement for proper tuning. You must have the bike tuned or have a matched calibration installed on your ECM to benefit from this kit.
I still have the stock exhaust system on my bike and the muffler valve is still active. Can I still install this?
- On 2008+ models you can, but it is a slightly different kit. Please specify that you have this configuration when ordering.
- On 2003 - 2007 models you cannot have Active Muffler Control and Baro sensing at the same time. You would need to have an aftermarket exhaust system without AMC installed in order to activate baro sensing.
I live in an area that is relatively flat. Will this feature help me?
Only when you travel to areas with significant elevation changes. Once your bike is tuned for your location you can safely run open loop or set a minimum AFV to prevent the ECM from leaning out the fuel delivery. Baro sensing would be good for those occasional long rides or if you do track days/racing in various locations.