Page 217 - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

2
Engine systems 201

Ignition angle

Engine speed
Load

Figure 2.246 Ignition map

Figure 2.247 Closed loop control with lambda sensor (with a second sensor after the catalytic
converter)
alive’ memory (KAM) of specifi c data such as adjustments, faults and deviations
in component performance may also be used. The RAM data is erased when the
ignition is switched off. The KAM data is erased when the battery is disconnected. Key fact
New data is replaced in the RAM and KAM during engine start-up and operation. The fi xed map of operating
During the cold-start and warm-up phases of engine operation the computer conditions specifi c for each engine is
held in a fi xed value memory or read
operates in an open loop mode based on the sensor data. Once the engine
only memory (ROM).
reaches a certain temperature and the signals from the EGO (or lambda) sensor
are logical, the computer operates in a closed loop mode based on the data from
this sensor ( Fig. 2.247 ).