Function of injection system: - ra07216020h10x(0010)

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U. Electronic diesel system (EDS) H. Charge pressure control (P2 control) Engines 602.96, 603.96/97 Turbo

U. Electronic diesel system (EDS)

h) Charge pressure control (P2 control) Engine 602.96
Basic Version Code 62/0 as of 06/91

as of Model Year 1990

as of Model Year 1991

as of Model Year 1992

Engine 603.971

Base version Code 62/0

as of model year 1992

A "characteristic map" (P2 control) is stored in the EDS control unit. The pressure values obtained as a function of injection quantity and engine speed produce an optimum engine operation in respect of performance, NO _x , HC and particle emissions.

Function

Particle emissions are lowered by reducing the pressure (P2) in front of the inlet valves under part load conditions.

A control circuit exists in the EDS control unit through which a pressure comparison of "P2 actual" and "P2 reference" is performed (refer to block diagram).

Any pressure difference is compensated for by the charge pressure control valve or by the pressure control flap.

These pressure actuators are operated by the vacuum transducers by means of an electronically adjustable vacuum.

Charge pressure control is dependent on:

Coolant temperature (up to 1991)
Intake air temperature (up to 1991)
Intake air pressure (pressure upstream of inlet valves)
Engine speed
Position of control rod (control rod travel)

Block diagram charge pressure control (P2 control), Engine 602.962

Model Year 1990

Model Year 1991

Fig 1: Block Diagram Charge Pressure Control (P2 Control), Engine 602.962

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Block diagram charge pressure control (P2 control), Engine 602.96

Basic Version Code 62/0 as of 06/91

as of Model Year 1992

Fig 2: Block Diagram Charge Pressure Control (P2 Control), Engine 602.96

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Block diagram boost pressure control (P2 control), engine 603.971

Base version Code 62/0

as of model year 1992

Fig 3: Block Diagram Boost Pressure Control (P2 Control), Engine 603.971

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.