WTF is Lambda and why is it important
10-14-2014, 02:18 PM
#1
Out Of Control!!
Thread Starter
WTF is Lambda and why is it important
Once again there has been so much HS,supposition, misinformation and misapplication about the automotive term "Lambda" that hopefully the following Mixture Adaption will clear the air.
The Lambda control system used by MB and most others precisely determines fuel injection duration so that the fuel/air ratio is consistently kept at a Lambda that equals 1(A Lambda of 1 is 14.7 kg of air per 1 kg of fuel) under all operating conditions.
Given the above we who diagnose automobiles are always confronted with the following variations.
Long Term Fuel Trim(Additive), also called Long Term Fuel Trim(LTF) is calculated while the engine is at idle. The maximum allowable correction to rich or lean is +/- 1.0 msec of the injection duration at idle.
Short Term Adaption(Multiplicative), also called Short Term Fuel Trim(STF), is calculated while the engine is at Low Partial Load and at High Partial Load. The maximum allowable correction to rich or lean is +/- 32% of the injection duration at Low or High partial load.
The engines ECU repeat the engines ECU is the control module that manages the Lambda=1 by providing instructions to the fuel injectors duration.
The 02 sensor is not a Lambda----simply a sensor that reports to the ECU voltage information enabling the ECU injector management function.
The Lambda control system used by MB and most others precisely determines fuel injection duration so that the fuel/air ratio is consistently kept at a Lambda that equals 1(A Lambda of 1 is 14.7 kg of air per 1 kg of fuel) under all operating conditions.
Given the above we who diagnose automobiles are always confronted with the following variations.
Long Term Fuel Trim(Additive), also called Long Term Fuel Trim(LTF) is calculated while the engine is at idle. The maximum allowable correction to rich or lean is +/- 1.0 msec of the injection duration at idle.
Short Term Adaption(Multiplicative), also called Short Term Fuel Trim(STF), is calculated while the engine is at Low Partial Load and at High Partial Load. The maximum allowable correction to rich or lean is +/- 32% of the injection duration at Low or High partial load.
The engines ECU repeat the engines ECU is the control module that manages the Lambda=1 by providing instructions to the fuel injectors duration.
The 02 sensor is not a Lambda----simply a sensor that reports to the ECU voltage information enabling the ECU injector management function.
