ME-SFI TWC Heating-Up Function

ME-SFI TWC Heating-up Function




Shown on Engine 119
158 Catalytic converter
B2/5 Hot film mass air flow sensor
B11/4 Coolant temperature sensor
L5 Crankshaft position sensor
M16/1 Electronic accelerator (EA)/ cruise control (CC)/ idle speed control (ISC) actuator
M33 AIR pump
N3/10 ME-SFI control unit
N15/3 ETC control unit
R4 Spark plugs
T1/1-T1/8 Ignition coils
CAN Data bus

The heating-up of the TWC is designed to heat up the catalytic converter more rapidly to its operating temperature and thus to sharply reduce the exhaust emissions.

The following systems are involved:
- Ignition system: In the idle speed and in line with coolant temperature, the ignition angle is retarded for e.g. approx. 20 seconds and the exhaust temperature thus increased.
- Idle speed control: In idle and depending on the coolant temperature the idle speed is increased to 1150 to 1500 rpm.
- Transmission shift delay: Coolant temperature dependent, is later upshifted on automatic transmission.
- Air injection After starting and during warm-up, the enriched mixture results in more unburned hydrocarbons in the exhaust. The injected air causes post-oxidation in the three way catalytic converter. This results in the release of heat that brings the three way catalytic converter quickly to operating temperature.