On idle run adaptations and compensations are performed within bank (in INPA visible in adaptation menu. 10%).įor idle run range the corrections (short-term fuel trims) and adaptations (long-term fuel trims) of offset type are used. N series engines (as an example) create short-term and long-term fuel trim for:Ī) idle run situation (up to approximately 1200 RPM) ī) working range (above 1300 RPM and/or loads above 5. In the image below you can see how N series engines perform short-term and long-term fuel trims:

information.īoth short-term and long-term fuel trims by their influence can be:Ī) offset or additive (+/- influence) – it means, they add or minus current value to correct the situation ī) multiplicative – it means, they multiples/divide with current value to achieve the necessary result. Differences form short-term tools:Ī) long-term fuel trims are immediately modified only when/if the current (for example, fuel) short-term tools can’t deal with it’s task in certain time and deeper/more extensive total adjustments are necessary ī) long-term fuel trims are stored in engine control unit and summoned every time, when the work is started Ĭ) nowadays engines create multi-dimension adaptation maps, which consist from data regarding: engine temperature, detonation sensors, fuel mixture, ignition, VANOS, EGR, accelerator pedal etc. They are long-term effect tool, which complements short-term fuel trims. They are not stored in engine control unit between driving sessions. They are short-term (as already suggested by name) effect tool, which works continuously, while the engine is running. Short-term trim is analogous (for older control modules) or digital (nowadays control modules) solution, which stabilizes one or another parameter (creates closed loop solution).įor example, fuel trims works in following way:Ī) by reading Lambda probe data, the engine control detects, if the fuel mixture is too lean or too rich ī) depending of Lambda reading value, the engine control performs opposite “sign”/direction correction to fuel supply to fix the situation (it means, to compensate the differences). Description applies not only to N43/N53 engines, but to all progressive BMW engines. In this entry you will find information about short-term fuel trims and long-term fuel trims.

Inpa bmw e90 n54