ME-SFI TWC heating-up function - GF07.61-P-3032F

ENGINE 104.941 /943 /944 /991 /994as of 1.8.96 

ENGINE 104.995 with CODE (494a) USA version with CODE (807) Model year 1997 with CODE (808) Model year 1998 with CODE (498) as of Model year 97 Japanese version 

ENGINE 111.943 /947 /951 /952 /955 /956 /957 /958 /973 /982 /983, 111.944 /975 as of 1.8.96, 111.946 as of 1.6.98, 111.921 /942 as of 1.9.98 

ENGINE 111.945 in MODEL 208.335/435 as of 1.6.98, 202.020 /080 as of 1.9.98 

ENGINE 111.974 with CODE (494a) USA version with CODE (807) Model year 1997 with CODE (808) Model year 1998 

ENGINE 112.910 /911 /912 /913 /914 /916 /917 /920 /921 /922 /923 /940 /941 /942 /943 /944 /946 /947 /949 /953 /954 /955 /970 /972 /973 /975 

ENGINE 113.940 /941 /942 /943 /948 /960 /961 /963 /965 /966 /967 /968 /969 

ENGINE 119.980 /981 /982 /985 

ENGINE 120.982/ 983 

ENGINE 137.970 

Shown on Engine 119 

Fig 1: ME-SFI TWC Heating-Up Function (Shown On Engine 119)

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.