ACCELERATIONSpeed variation as a function of time.
ACTUATOR DIAGNOSIS During normal driving, many Motronic functions are operational only under specific conditions. This renders it impossible to activate all actuators (such as the EGR valve) for operational checks while on the road.
ACCERERATION ENRICHMENTDuring acceleration, the L-Jetronic meters additional fuel to the engine. If the throttle is opened abruptly, the air-fuel mixture is momentarily leaned-off, and a short period of mixture enrichment is needed to ensure good transitional response.
ACCELERATION RESPONSE The good acceleration response is a result of overswing of the air-flow sensor plate. Transitions from one operating condition to another produce changes in the mixture ratio which are utilized to improve driveability.
ADDITIVEChemicals added to fuel in very small sizes to improve and maintain fuel value. Detergents and corrosion inhibitors are examples of gasoline additives.
AIRHEAD R-BIKESWay back after World War I, BMW was prohibited from making any 'machines of war' which primarily included airplanes. The brass at BMW decided that they'd like to stay in business, so they borrowed an engine design that reminded them of an airplane engine -- the Boxer -- to put into a motorcycle. That engine design stayed with them for a long, long time, and its penultimate (so far) form was the Airhead.
ALTITUDEA measure of distance above sea level.
AIR-MASS METERThe hot-wire and hot-film air-mass meters are thermal load sensors. They are installed between the air filter and the throttle valve and register the air-mass flow [kg/h] drawn in by the engine. Both the sensors operate according to the same principle.
AIR-TEMPERATURE SENSOR The air-temperature sensor incorporates a NTC resistor element. Changes in intake-air temperature can be registered immediately, the resistor protrudes from the end of a trunk shaped molding into the area of maximum air-flow speed. The 4-pole plug-and-socket connection includes the plug for the fuel injector.
AIR/FUEL MIXTUREOperation of the spark-ignition engine is contingent upon availability of a mixture with a specific air/fuel ratio. The theoretical ideal for complete combustion is a mass ratio of 14.7:1, referred to as the stoichiometric ratio. In concrete terms this translates into a mass relationship of 14.7 kg of air to burn 1 kg of fuel, while the corresponding volumetric ratio is roughly 9,500 liters of air for complete combustion of 1 liter of fuel.
AIR/FUEL RATIOBecause the A/F ratio is a crucial factor in defining an engine's emissions, the engine-management system is of immense importance in determining exhaust content.
AMBIENT-PRESSURE SENSOR The ambient-pressure sensor shares its design with the manifold-pressure sensor, but is located inside the ECU. Barometric pressure readings are needed by systems that rely on throttle-valve aperture instead of an air-mass meter to monitor the incoming air supply. The precise data on ambient air density registered by this sensor serve as a significant factor in numerous diagnosis functions.
ANALOG-DIGITAL CONVERTER The signals from the throttle-valve potentiometer are continuous analog signals. As are the lambda-sensor signal, the engine-temperature signal, the intake-air signal, the battery voltage, and a voltage-reference signal generated in the ECU. These analog signals are converted to data words by the analog-digital converter and transmitted to the microprocessor via the data bus.
ARCTIC CATManufacturer of power sports equipment and recreational vehicles.