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Exhaust Treatment Function - GF14.00-P-3000MRT

Engine 256.9 in model 213, 238, 257, 290 

up to model year 2021 

Engine 256.9 in model 222 

Function requirements, general 

IMPORTANT The ME-SFI [ME] control unit (N3/10) detects the engine running via the evaluation of the crankshaft Hall sensor signals (B70). The ME-SFI [ME] control unit directly reads in the signals of the crankshaft Hall sensor.

Exhaust treatment 

The exhaust gas cleaning reduces the harmful components of the combustion gases and residues emitted by the engine.

The following are involved here:

The harmful constituents are reduced through reduction and oxidation in the three-way catalytic converter, filtration in the gasoline particulate filter, and controlled exhaust gas recirculation.

The gasoline particulate filter is installed under the following conditions:

Exhaust gas cleaning in three-way catalytic converter 

For a three-way catalytic converter, the operating temperature is decisive. Noteworthy pollutant conversion only starts from an operating temperature of approx. 250°C.

Ideal operating conditions for high conversion rates and a long service life prevail in the temperature range from approx. 400 to 800°C. To quickly reach this temperature, an upshift delay of max. 60 s is realized in the case of a cold start (coolant temperature < 50°C). However, the upshift delay is only active up to a speed of 53 km/h. An upshift thus initially occurs at higher engine speeds.

The ME-SFI [ME] control unit transmits the upshift delay depending on the coolant temperature and wheel speed via the drive CAN (CAN C1) to the fully integrated transmission control unit (Y3/8n4) (model 213, 222, 238) or to the fully integrated transmission control electric controller unit control unit (Y3/8n4) (model 257, 290).

The ME-SFI [ME] control unit reads in the signals of the coolant temperature sensor (B11/4) directly.

The Electronic Stability Program control unit (N30/4) transmits the wheel speed to the ME-SFI [ME] control unit via the suspension FlexRay (Flex E), the powertrain control unit (N127) and the drive CAN.

Chemical conversion takes place in the three-way catalytic converter at λ = 1.

Through oxidation, the carbon monoxide (CO) is converted into carbon dioxide (CO2 ) and the hydrocarbon (HC) into water (H2 O) and carbon dioxide (CO2 )

Through reduction, the nitrogen oxide (NOx ) is converted into nitrogen (N2 ) and carbon dioxide (CO2 ).

Once the operating temperature is reached and lambda control has been enabled, the function of the three-way catalytic converter is monitored by the ME-SFI [ME] control unit.

For this purpose, the ME-SFI [ME] control unit reads in the signals from the following component parts:

The ME-SFI [ME] control unit assesses the oxygen storage capacity of the three-way catalytic converter and, with that, assesses its aging.

IMPORTANT Any oxygen exceeding the amount required for the three-way catalytic converter to oxidize carbon monoxide (CO) is stored. If the oxygen present in the exhaust gas is not sufficient for oxidizing the carbon monoxide (CO), the stored oxygen is fully or partially removed. In combination with the high oxygen storage capacity of the three-way catalytic converter, this procedure achieves an almost complete compensation for the fluctuations in oxygen concentration upstream of the three-way catalytic converter. The oxygen storage capacity, and thus the function of the three-way catalytic converter, can be assessed on the basis of the lambda sensor signals upstream and downstream of the three-way catalytic converter. In the case of a fully functional three-way catalytic converter, high values and changes are measured upstream and downstream of the three-way catalytic converter. In contrast, the lambda sensor signal downstream of the three-way catalytic converter is virtually constant. As the aging process advances, the oxygen storage capacity of the three-way catalytic converter, and thus its ability to convert carbon monoxide (CO) and hydrocarbons (HC), is reduced. Consequently, the lambda sensor signal downstream of the three-way catalytic converter becomes increasingly similar to the lambda sensor signal upstream of the three-way catalytic converter.

The lambda sensor signals upstream and downstream of the three-way catalytic converter are compared. If both signals are almost identical, the three-way catalytic converter is no longer operational. Several measurements are performed in the lower partial-load range at specified rotational speeds. The results are compared with a characteristics map in the ME-SFI control unit.

Where a defect is detected, a fault message is output in the instrument cluster (A1). The ME-SFI [ME] control unit transmits the request to display the fault message via the drive CAN, the powertrain control unit, the suspension FlexRay, the electronic ignition lock control unit (N73), and the user interface CAN (CAN HMI) to the instrument cluster.

Recognized fault are stored in fault memory of the ME-SFI [ME] control unit. These can be read out and deleted with the vehicle diagnosis system.

Exhaust gas cleaning in gasoline particulate filter (model 238 with code 472 (Gasoline particulate filter) or model 213, 222, 238, 257, 290 with code 598 (Gasoline particulate filter (GPF) with sensor system), model 213, 238, 257, 290 with code 961 (Exhaust system with GPF generation 2.0)) 

The gasoline particulate filter absorbs the emitted soot particles and regenerates itself under specific operating conditions.

The regeneration (soot combustion) of the gasoline particulate filter takes place while the vehicle is being operated in a conventional driving style, predominantly in overrun mode. Soot combustion occurs as soon as sufficient oxygen is available in the gasoline particulate filter.

For vehicles with code 598 (Gasoline particulate filter (GPF) with sensor system) or code 961 (Exhaust system with GPF generation 2.0), the exhaust gas temperature and soot content of the gasoline particulate filter are continuously monitored.

The exhaust gas temperature is registered by the temperature sensor upstream of the gasoline particulate filter (B163/4). The soot content is determined by the gasoline particulate filter differential pressure sensor (B163/3). The ME-SFI [ME] control unit reads the sensor signals in directly and evaluates them. If the measured values exceed specific limits, the ME-SFI [ME] control unit initiates appropriate interventions in the engine timing and requests a warning message in instrument cluster.

Reduction of pollutants through exhaust gas recirculation 

The formation of nitrogen oxides (NOx ) is reduced via the exhaust gas recirculation in the combustion chamber.

This is carried out by slowing down burning. As a result, temperature peaks are avoided that favor the formation of nitrogen oxides (NOx ).

Exhaust gas recirculation also helps to reduce charge change losses, and therefore also reduces fuel consumption in partial-load range.

IMPORTANT The ME-SFI [ME] control unit determines the valve overlap by actuating the intake camshaft adjustment solenoid (Y49/1) and the exhaust camshaft adjustment solenoid (Y49/2). Internal exhaust gas recirculation is therefore regulated within certain limits.

  Electrical function schematic for exhaust treatment Engine 256.9 in model 213, 238 up to model year 2021 PE14.00-P-2051-97DBA
    Engine 256.9 in model 222 PE14.00-P-2051-97SEM
    Engine 256.9 in model 257, 290 up to model year 2021 PE14.00-P-2051-97XBB 
  Overview of system components for gasoline injection and ignition system with direct injection   GF07.70-P-9998MRT
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