Long-Term Fuel Trim Bank X, Lower Part Load

Measurement range: 0-2.

Multiplicative adaptation of the short-term fuel trim (correcting the injection period), adaptation that occurs at lower part load (normal road driving). The value stored in the control module indicates how much the short-term fuel trim in the upper part load range has been corrected so that the short-term fuel trim value can again oscillate around 1 at the lower part load. In the event of low fuel pressure for example, the value will increase (= longer injection time). This is to compensate the fuel/air mix for the lack of fuel. Normal value 1±0.1. The lower part load range of the engine must be reached for the value to be updated (normal road driving). Approximately 30 minutes of driving in the lower part load may be required before the adaptation is complete (complete = short-term fuel trim oscillates around 1 at lower part load). Value over 1: the control module increases the injection period (to prevent a lean fuel / air mix). Value under 1: the control module decreases the injection period (to prevent a rich fuel air mix).

HINT: When diagnostic trouble codes (DTCs) are erased, the adaptation returns to 1.