Cis-E System: Description
The fuel injection system used on all Mercedes-Benz gasoline engine vehicles uses a basic CIS injection system for fuel delivery and electronic controls for mixture correction functions.
Electronic controls consist of airflow sensor position indicator (potentiometer), electro-hydraulic actuator, thermo time switch, coolant temperature sensor, Electronic Control Unit (ECU), transistorized ignition system, throttle valve microswitch, altitude sensor, lambda control and oxygen sensor.
If ECU malfunctions, CIS-E system will operate in back-up or "limp-home" mode until fuel system can be repaired. On 420 and 560 series vehicles, various components of the CIS-E injection system are monitored by a self-diagnosis feature in the control unit. The failure codes are transmitted to the lambda measuring circuit of the diagnostic socket. These codes are displayed on a Bosch "On-Off" Ratio Tester (KDJE-P600 ). The fixed on-off ratio indicates possible malfunctions.
The EZL electronic breakerless ignition system has computer controlled electronic ignition timing (firing point) adjustment. Data about ignition characteristics for various engine loads is stored in the ignition control module and can be recalled according to actual engine operating conditions.