Glossary

 

Lambda: actual ratio of AFR (air-fuel ratio).

Lambda 1.00: Stoichiometric fuel mixture (ratio air/fuel: 14.8/1 in normal conditions) – after burning no leftover of air or fuel.

Lambda <1.00: rich mixture (fuel leftover); Lambda >1.00: lean mixture (air leftover).

Stoichiometric mixture: air/fuel ratio (in normal conditions)14.8/1; Lambda 1.00.

 

Homogeneous mixture mode:

a) Lambda 1.00 or rich mixture (to ensure max torque);

b) injection of fuel – in the expansion stroke.

 

Homogeneous lean mixture mode (possible only for direct injection engines):

a) Lambda around 1.50;

b) injection in two steps: in the expansion stroke and directly before ignition of the fuel mixture.

 

Stratified charge mode (possible only for direct injection engines):

a) Lambda 2.0 .. 3.5;

b) injection directly before ignition of the fuel mixture.

 

Lambda probe – sensor for control of the fuel mixture.

Narrow-band Lambda probe – sensor, intended to control the stoichiometric fuel mixture (Lambda = 0.99 .. 1.01);

Wide-band Lambda probe – sensor, able to measure Lambda from 0.60 to clean air conditions (Lambda = 30.00+).

Main Lambda probe – Lambda sensor, which is used to adjust the fuel mixture, placed before CO catalytic converter;

Control Lambda probe – placed after CO catalytic converter and performs following tasks:

a) measures the performance of CO catalytic converter;

b) controls plausibility of the signal of the main probe and also calibrates the main probe (if wide-band Lambda probe is used as the main probe).

 

Heating of Lambda probes – power supply to additional heating elements of the probe to ensure necessary temperature (around 800 oC).

Preheat – heating of the Lambda probe with small voltage/current (to 10 .. 20% of optimal) to avoid thermal shock and condensation.

 

Nernst resistance – internal resistance of the Lambda probe element, which characterizes it’s (probe’s) Chemical efficiency (ability to perform normally).

 

Bank – the group of cylinders, controlled by a single, common main Lambda probe.

 

Adaptations – coefficient of corrections, applied to some parameters (for example, the opening time of the injectors), which is created, based on “self-learning” process of the engine to ensure the max optimal performance of current knot/engine.

 

Compensations – coefficient of corrections applied to some parameters (for example, fuel supply), which is in short-term applied to ensure momentous correction of the situation.

 

Fuel adaptations – LTFT (long-term fuel trim);

Fuel compensations – STFT (short-term fuel trim), also: integrators.

 

Offset type LTFT – fuel adaptations, applied to an idle mode;

Multiplicative type LTFT – fuel adaptations, applied to low/average/high load.

 

Individual adaptations of cylinders – adaptations of the fuel amount, applied to each cylinder.

Mechanical efficiency tests of cylinders – measurements of performance of each cylinder, which are performed, measuring changes in speed of the flywheel.

Chemical efficiency tests of cylinders – measurements of performance of each cylinder, which are performed, measuring changes of Lambda, changing fuel supply in the cylinder.

 

Rough run data – the result of the mechanical efficiency of cylinders (idle).

 

Flywheel adaptations – data of each flywheel “tooth’s” technological deviation from the ideal.

 

VANOS offset – a difference of detected position of the camshaft and ideal position when VANOS is deactivated.

 

PWM – pulse-width modulation. Are used to regulate/manage parameter/sensor. For example – to change the opening of the solenoids, heating of Lambda probes etc. Characterizing parameter: relative “fulfillment”: 0 .. 100%.

 

Misfire – fault in fuel ignition; combustion stroke – without fuel ignition.

Group misfire – a series of misfire in the current cylinder.

 

NOx sensor – device, measuring nitrites in the exhaust. NOx sensor performs:

a) measuring of wide-band and narrow-band Lambda in the exhaust;

b) nitrite (indirectly – also performance of the NOx catalytic converter) measuring.

 

Regeneration of NOx catalytic converter – short-term (for second or two), periodical (interval 10 .. 50 seconds) enrichment of the fuel mixture in the exhaust (Lambda down to 0.80) to increase the temperature in the exhaust and “cleaning” of the NOx catalytic converter – preparation to next cycle (accumulation of nitrites);

Desulphation of NOx catalytic converter – periodical (after each 1500 .. 7000 km) long-term (20 .. 40 minutes) increasing of temperature (to 600 oC) in the exhaust (Lambda around 0.95) to clean the NOx catalytic converter of sulfur.

 

Coding data of the injectors – reaction time and flow-rate data, marked on injectors.

Encoding of the injectors – input of injector coding data in the memory of the engine management unit.

 

Driving session – new driving cycle, before it:

a) ignition and engine: OFF;

b) MSD status: OFF (lighting of Start/Stop button: turned off).