Emission control, function - GF14.00-P-3000PX

ENGINE 642 in MODEL 164.1 /8, 203.0 /2, 209.3 /4, 221.0 /1, 251.0 /1 with CODE (474) Particulate filter 

ENGINE 642.920 in MODEL 211.020 /220 /222 /620, 219.322 with CODE (474) Particulate filter 

ENGINE 642.921 in MODEL 211.084 /089 /284 /289 with CODE (474) Particulate filter 

ENGINE 642.920 in MODEL 211.022 except CODE (494) USA version with CODE (474) Particulate filter 

ENGINE 642.920 in MODEL 211.022 /222 with CODE (498) Japan version 

ENGINE 642 in MODEL 461.3 with CODE (474) Particulate filter 

ENGINE 642 in MODEL 463.3 with CODE (474) Particulate filter 

The exhaust gases output by the engine are cleaned by the exhaust system, an oxidation catalytic converter (catalytic converter (TWC)) and a diesel particulate filter (DPF). The catalytic convertor is also used to reduce noise pollution. The task of the exhaust gas cleaning it observance of the limits for exhaust gas emissions set by the lawmaker in which the following pollutants in the exhaust gas are reduced:

• Nitrogen oxide (NO_X )
• Hydrocarbons (HC)
• Carbon monoxide (CO)
• Particulate matter (particles) (PM)

The following sub-functions support emission reduction:

• Intake port shutoff (EKAS), via the intake port shutoff motor (M55) (except model 461)
• Diesel particulate filter preheating via the glow time output stage (N14/3)
• Exhaust gas recirculation (AGR), via the left exhaust gas recirculation positioner (Y27/9) (except model 461) or the exhaust gas recirculation actuator (Y27/9) (model 461)
• Boost pressure regulation via the boost pressure positioner (Y77/1)

The DPF is combined with the TWC connected in series to make an emission control system. The upstream TWC lowers the HC and CO and generates the required thermal energy for the DPF regeneration phase by means of afterburning. The diesel particulate filter consists of a ceramic honeycomb filter body made out of silicon carbide, which is coated with rare metal platinum.

The passages of the diesel particulate filter are opened alternatively at front and rear and are separated from each other through the porous filter walls of the honeycomb filter body. The precleaned exhaust which has passed though the oxidation catalytic converter flows into the ducts of the DPF which are open to the front at the front and passes through the porous filter walls of the honeycomb filter body into the ducts which are open to the rear. After this, the cleaned and filtered exhaust is dissipated through the exhaust system. The particles are retained in the honeycomb filter body of the DPF.

The reduction of the PM share is approx. 99 %.

Regeneration of the DPF 

If the PM load exceeds the performance map dependent value, the CDI control unit (N3/9) starts the regeneration phase according to the given regeneration conditions. The CDI control unit receives the load condition of the DPF via the pressure differential sensor (DPF) (B28/8) (except model 463) and via the pressure differential sensor (catalytic converter) (B28/8) (model 463).

Regeneration takes place via a periodical increase of the exhaust temperature. For this purpose, the following functions are taken over by the CDI control unit:

• An additional post-injection
• DPF preheating

An increase in the exhaust gas temperature causes the PM retained in the DPF to be burnt to primarily produce carbon dioxide (CO₂ ). The ash produced remains in the DPF. The exhaust gas temperature is monitored during the regeneration by the temperature sensor upstream of the diesel particulate filter (B19) and the temperature sensor upstream of TWC (B19/9). The pressure differential sensor determines the pressure difference between the exhaust gas pressure upstream and downstream of the DPF via the exhaust gas pressure lines upstream and downstream of the DPF. The soot load in the DPF is determined using a performance map on the basis of pressure difference and the exhaust mass calculated by the CDI control unit. The engine diagnosis indicator lamp indicates the required maintenance of the DPF (A1e58) (except model 461, except code (494) USA version).

On model 461, the required maintenance of the DPF is displayed via the EDC (Electronic-Diesel-Control) (A1e34) diesel indicator lamp in the instrument cluster (A1). On vehicles with code (494) USA version, the required maintenance of the DPF is signalled by the CHECK ENGINE indicator lamp (A1e26).

Interrupted regeneration is distributed over several driving cycles for short distances. Until the specified regeneration temperature is reached several heating-up phases are required. Regeneration occurs unnoticed by the customer.