How to diagnose most Buell EFI problems

[upaero]

I have added this section below to the troubleshooting page at rev-mo.com/efitroubleshoot. Instead of randomly replacing parts based on a hunch or something you read online you can actually see what each sensor is feeding the ECM and how it effects the fueling, in real time. It may not tell you exactly what the problem is, but it will tell you what it isn't. If you seek help from others armed with this information it is extremely helpful too. The tutorial for using the Data Channels page of Ecmdroid is at rev-mo.com/livedata.



PERFORM DIAGNOSTICS USING LIVE DATA

The Buell ECM makes adjustments based on data it receives from sensors located on the bike. If the data from a sensor isn't accurate the bike won't run right, or maybe not at all. There aren't very many sensors and viewing the data is easy, so the process of elimination doesn't take long. Below is a screenshot of how you can set up your Data Channels Page of EcmDroid which will allow you to troubleshoot or narrow down a vast majority of EFI related problems WITHOUT spending money on parts or getting your hands dirty. There are numerous other parameters that can be viewed but this is a good place to start.

Troubleshoot screen shot.jpg

TPD (Throttle Position Degree)

On pre-2008 models, when the idle is adjusted to about 1100 RPM with engine fully warmed up, this should be about 5 degrees. On 2008+ models it should be about 4 degrees. When the throttle is moved it must change at a steady rate without any dead spots or spikes. At WOT it must read 85 degrees.
​
AFV (Adaptive Fuel Value)
​
In factory closed loop operation, the ECM will make adjustments to the overall fuel delivery based on O2 sensor data. At or near sea level this number should be close to 100. If it is significantly higher than 100 it could be a sign of a fuel delivery problem so it would be a good idea to measure fuel pressure (on 1125 and 2010 XB models fuel pressure can be viewed on a data channel). If this number is significantly lower than 100 you can isolate the problem by disabling closed loop which takes the O2 sensor out of the equation. Remember that in closed loop operation, the ECM will use AFV to adjust for issues caused by mechanical problems. It is also common for this to be at an unnecessarily low value, even when all sensors are working properly.
​
IAT Corr (IAT Correction)

This shows you the percentage of fuel compensation the ECM is making based on the Intake Air Temp sensor. Generally speaking, it should be more than 100 in cold air and close to 100 on warm days and while riding. With factory settings the ECM will lower the IAT Corr (reducing fuel delivery) when the air temperature reading is abnormally high, which actually exasperates the problem.

WUE (Warm Up Enrichment) and CLT (Engine Temp)

Warm Up Enrichment is based on engine temp or CLT (measured by the head temp on air cooled models, and coolant temp on 1125 models). When the bike is completely cold the CLT should read ambient temperature. As the bike warms up the CLT should increase and WUE should decrease until operating temperature is reached. At this point the WUE should be close to 100. If, for example, the head temp sensor on an XB is loose or defective the ECM will continue to enrich the fuel delivery unnecessarily which will be seen as a constantly high WUE number. Also, the calibration or "learn" mode for AFV will not be active until a minimum CLT number is reached (on XB models the factory setting is 130). Without accurate temp sensing the engine will never run correctly.


Hopefully this will help save people a lot of money and headaches.