Thermal Management, Function - GF07.10-P-1012MMX

ENGINE 276.8 in MODEL 166 

as of model year 2016 

ENGINE 276.8 in MODEL 292 

Function requirements for thermal management, general points 

• Circuit 87M (engine management ON)
• Engine runs

Thermal management, general 

The coolant temperature of the engine is regulated with the thermal management controlled by the ME-SFI [ME] control unit (N3/10). The following advantages arise from this:

• Rapid reaching of the optimal operating temperature
• Reduction of the exhaust emissions
• Fuel saving (up to about 4%)
• Improved heating comfort

Function sequence for charge air cooling

The function sequence for charge air cooling is described in more detail in the document Charging function  .

Thermal management controlling is dependent on the following sensors and signals:

• Coolant temperature sensor (B11/4), coolant temperature
• Charge air temperature sensor (B17/8), charge air temperature
• Pressure sensor downstream of throttle valve (B28/7), engine load
• Accelerator pedal sensor (B37), accelerator pedal actuation (how quickly and how far vehicle type quiet or sporty)
• Crankshaft Hall sensor (B70), engine rpm
• Temperature sensor in the ME-SFI [ME] control unit
• Instrument cluster (A1), speed via the chassis CAN 2 (CAN E2) and chassis CAN 1 (CAN E1)
• SAM control unit (N10), outside temperature via the interior CAN (CAN B) and chassis CAN 1
• Automatic air conditioning control and operating unit (N22/7), air conditioning system status over interior CAN and chassis CAN 1
• Electronic Stability Program control unit (N30/4), wheel speed via the chassis CAN 1
• Fully integrated transmission control unit (Y3/8n4), status of transmission oil temperature via the drive train CAN (CAN C)

Function sequence for thermal management 

The thermal management is described in the following points:

• Function sequence for heating the two-disk thermostat 
• Function sequence for fan control 
• Function sequence for overheating protection 

Function sequence for heating the two-disk thermostat 

The temperature of the coolant can be controlled variably by the heatable two-disk thermostat. There is a coolant thermostat heating element (R48) in the two-disk thermostat which is actuated a required by the ME-SFI [ME] control unit using a ground signal.

The two-disk thermostat can take four positions:

• Full throttling 
• Bypass mode 
• Mixed-fuel mode 
• Radiator operation 

Positions of two-disk thermostat 

Full throttling 

• Heating element deenergized, coolant temperature < 65°C The coolant thermostat is closed.

Bypass mode 

• Heating element deenergized, coolant temperature < 100°C
• Heating element deenergized, coolant temperature < 65°C

According to the meaning of optimal in-engine friction and therefore fuel saving the coolant temperature can be increased to about 105°C in partial-load range (heating element deenergized).

Therefore the friction power can be improved due to a higher engine oil temperature and the mixture formation improved due to less fuel condensation on the cylinder barrels.

Mixed-fuel mode 

• Heating element deenergized, coolant temperature 100 up to 115°C
• Heating element deenergized, coolant temperature 65 up to 100°C

Radiator operation 

• Heating element deenergized, coolant temperature < 115°C
• Heating element deenergized, coolant temperature < 100°C

Through heating the two-disk thermostat (heating element energized) opens this and the coolant is led through the engine radiator.

For wide open throttle the two-disk thermostat is very quickly opened. The coolant temperature can be lowered to about 80°C whereby best possible engine cooling and knock-free combustion are achieved.

Above an about 115°C coolant temperature the two-disk thermostat is always fully open independent of the flowrate through the heating element (limp-home function).

Function sequence for fan control 

The ME-SFI [ME] control unit actuates the fan motor (M4/7). Here the target fan speed is prescribed over a pulse width modulated signal by the ME-SFI [ME] control unit.

The duty cycle of the pulse width modulated signal is 10 to 90%.

Here for example the following mean.:

• 10% fan motor off "OFF"
• 20% fan motor "ON", minimum rpm
• 90% fan motor "ON", maximum rpm

For faulty actuation the fan motor rotates at its maximum rotational speed (fan emergency mode).

Its status is transmitted to the fan motor as a ground signal over the actuation line.

The automatic air conditioning control and operating unit transmits its status via the interior CAN and chassis CAN 1 to the ME-SFI [ME] control unit.

Delayed fan switch off 

The fan motor runs on for "ignition OFF" for up to 6 minutes if the coolant temperature or the engine oil temperature has exceeded the prescribed maximum values.

The duty cycle of the pulse width modulated signal for delayed fan switch off is a maximum of 40%.

If the on-board electrical system voltage drops down a lot, the delayed fan switch off is suppressed.

Function sequence for overheating protection 

In a case of thermal overload the overheating protection protects the catalytic converters against engine damage and overheating damage.

In the case if an excessively high coolant or intake air temperature the throttle valve of the throttle valve positioner (M16/6), is no longer fully opened by the ME-SFI [ME] control unit dependent on the engine rpm and load. The ME-SFI [ME] control unit shortens the injection period of the fuel injectors (Y76) according to the lower air mass.

Furthermore the heating element in the coolant thermostat is actuated by the ME-SFI [ME] control unit so that the two-disk thermostat is fully opened and the whole coolant is cooled over the engine radiator.

If engine oil or coolant temperature is too high, a warning message is shown in the multifunction display (A1p13) on the instrument cluster. To do this the ME-SFI [ME] control unit sends an appropriate signal via the chassis CAN 1 and the chassis CAN 2 to the IC.

	Electrical function schematic for heat management		PE07.10-P-2712-97NBA
	Overview of system components for gasoline injection and ignition system with direct injection	ENGINE 276.8 in MODEL 166 (except 166.063) as of model year 2016 ENGINE 276.8 in MODEL 292	GF07.70-P-9998MMX
		ENGINE 276.8 in MODEL 166.063 as of model year 2016	GF07.70-P-9998MMM