Passat L4-1984cc 2.0L DOHC (9A) (1990)
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Engine Control Module: Description and Operation
Federal Models
CIS-E Motronic Engine Management System
The CIS-E Motronic control unit, which is located at the center rear of the engine compartment, receives and evaluates information provided by various
sensors concerning engine operating conditions. It is responsible for management of the fuel injection, ignition, idle speed, and fuel tank evaporative
emission control systems. Input signals to the Motronic control unit include:
^
Air flow sensor plate potentiometer
^
Automatic transmission selector switch
^
A/C compressor input
^
Coolant temperature sensor
^
Hall sender
^
Ignition reference sender
^
Knock sensors
^
Oxygen sensor
^
Throttle valve switches
From the information received, the Motronic control unit calculates the appropriate values for the output components, necessary to maintain optimum
engine performance and emission characteristics. Output signals from the Motronic control unit include:
^
Cold start valve
^
Diagnostic codes
^
Differential pressure regulator
^
Fuel pump relay
^
Evaporative emission solenoids
^
Idle stabilizer valve
^
Ignition power output stage
ADAPTIVE FUEL MIXTURE CONTROL
In order to maintain proper performance and driveability over a wider range of conditions, and to reduce the need for minor periodical adjustments, the
CIS-E Motronic control unit can adapt to minor intake leaks, engine wear, and sustained high altitude operation. It does this by learning the control
values that are most often required to maintain correct engine operation under normal conditions. If the "learned" conditions of operation change (i.e.
changing from driving at sea level 35 ft., to mountain driving at 3000 ft.) the control unit will adapt the air/fuel mixture to prevent the rich or lean
condition that would result otherwise.
FAULT MEMORY
