GF07.61-P-3032CY ME-SFI Catalytic Converter Heating-Up, Function

GF07.61-P-3032CY ME-SFI Catalytic Converter Heating-up, Function
- up to model year 08

Heating-up of the TWC is designed to heat up the firewall catalytic converters more rapidly to its operating temperature and thus leads to reduced exhaust gas emissions for a cold start.
The ME-SFI [ME] control unit (N3/10) is able to detect that the operating temperature has been reached and that the firewall catalytic converters are operating at normal efficiency from the signals supplied by oxygen sensors.

The following input signals determine whether TWC heating is enabled:
^ Coolant temperature at engine start
^ Difference between intake air and coolant temperature for engine start
^ Residual heat for firewall catalytic converters (from temperature model calculation)
^ Altitude (atmospheric air pressure)
^ Air mass

The following subsystems are involved in TWC heating-up:
^ Ignition system -> In the idle speed range and in line with the coolant temperature the ignition angle is retarded for e.g. 20 s in order to increase the exhaust gas temperature.
^ Idle speed control -> Dependent on coolant temperature, the idle speed is increased to approx. 1100 to 1300 rpm for up to 20 seconds.
^ Transmission shift delay (with automatic transmission 722.9) -> Depending on the coolant temperature, the automatic transmission is upshifted with a delay.
^ Air injection -> Because of the enriched fuel-air mixture after start and in the warming-up phase there are many more uncombusted hydrocarbons in the exhaust. The blow in air ensures after burning in exhaust ducts and in the firewall catalytic converter for.
^ camshaft adjustment -> Special positions for the intake and exhaust camshafts are specified for TWC heating.