I'm working on a DIY tune, and have read the DIY tuning on this forum and Anjuna's N55 tuning on the E90 forum, and could use some help understanding the axis values on the WGDC PID factor tables. I know the P factor X axis is airflow but not sure what the Y axis is, it ranges from -0.125 to +0.188. The I factor table has RPM as the Y axis but again the X axis ranges from -.200 to +.400. The D factor table has X axis of -.028 to +.017 and Y range is -.313 to +.188. What I've read is the numbers that are not RPM and MAF are "error" but haven't found what that means. Is that a count of errors from a certain point? Is it an error number thrown by the DME code? Before I start to "tune" these tables I'm hoping to understand the values, rather than having to change a value, either the axis or cell value, and reviewing the result in the log. I'm taking the PID method approach to tuning my E series N55.