Block Learn Multiplier
From GM Wiki
(Redirected from BLM)
The Block Learn Multiplier (BLM) is a long term adjustment , which is stored permanently (unless you disconnect power to the ECM), to the fuel delivery calibration that results from the ECM "learning" the characteristics of your engine while you are driving around. A value of 128 is ideal, because it is the center point in a of range 0-255. Above 128, and the ECM is adding fuel to compensate for a lean condition at a particular load and RPM. Below 128, and it represents the opposite, a reduction of fuel to correct for a rich condition.
See: ECM Tuning to understand in context how the BLM is used.
