System Description

CIS-E Motronic Engine Management System:

CIS-E MOTRONIC FUEL INJECTION SYSTEM
A mechanical hydraulic injection system provides the basis for the Bosch CIS-E Motronic Fuel Injection System. The mechanical portion of the CIS-E Motronic system consists of the Mixture Control Unit (Air Flow Sensor and Fuel Distributor combination), Diaphragm Pressure Regulator, Fuel Accumulator, Cold Start Valve, Fuel Injectors, two separate Fuel Pumps, Fuel Reservoir, Fuel Filter, Fuel Lines and the Fuel Tank. In addition, electrical controls such as the Differential Pressure Regulator have been added for increased flexibility to meet todays more stringent performance and exhaust emission requirements. Refer to COMPUTERIZED ENGINE CONTROLS for a detailed description of electronically controlled components.

The basic function of the CIS-E Motronic Fuel Injection System is to meter fuel to the engine dependent upon the quantity of air drawn in by the engine (which is the main actuating variable). The stream of air drawn in by the engine deflects the Air Flow Sensor, which in turn actuates the Fuel Distributor Control Plunger. Depending upon its position, the control plunger opens or closes the fuel-metering ports. The metering ports supply fuel through the pressure regulating valves to the individual fuel injectors. The CIS-E Motronic system also takes a number of additional engine operating data into account by means of sensors. The output signals from these sensors are processed by the CIS-E Motronic Control Unit that controls the Differential Pressure Regulator which adapts the injected fuel quantity to the various operating conditions. In the event of a major system malfunction, the CIS-E Motronic system operates solely with the basic function (CIS), and the driver then has a system at his disposal which provides a good limp-home capability when the engine is not performing at optimum efficiency.

A special feature of the CIS-E Motronic engine management system is its adaptive capability. The system literally changes its own normal operating range to compensate for engine wear, minor vacuum leaks, or different operating conditions such as change of altitude. Many of the periodic adjustments that used to be required to keep the engine running at its best are now done automatically by the engine management system.

The CIS-E Motronic system also features built-in diagnostic circuitry that monitors the normal range of operating values, detects unusual values and other faults, and stores fault information for later recall. Faults related to safety or emission control are stored in permanent memory, which needs to be cleared after the necessary service or repair is completed. The first step in any CIS-E Motronic system troubleshooting must be to check the control unit fault memory, and to find and correct any faults that may be indicated. Refer to COMPUTERIZED ENGINE CONTROLS for proper proceders concerning fault code retrieval and interpretation.

FUEL SYSTEM COMPONENTS
These components are related to fuel and air delivery portion of the CIS-E Motronic system and will be addressed in this section.

^ Accelerator Pedal
^ Air Cleaner
^ Air Flow Sensor
^ CO Adjustment Screw
^ Cold Start Valve
^ CO Tap
^ Fuel Accumulator
^ Fuel Distributor
^ Fuel Filter
^ Fuel Injector Insert
^ Fuel Injectors
^ Fuel Pressure Regulator (Diaphragm)
^ Fuel Pump
^ Fuel Pump Relay
^ Fuel Reservoir
^ Fuel Return Lines
^ Fuel Supply Lines
^ Fuel Tank
^ Fuel Transfer Pump
^ Idle Air Bypass Screw
^ Idle Mixture
^ Idle Speed
^ Intake Air Hoses
^ Idle Stabilizer Valve
^ Intake Manifold
^ Mixture Control Unit
^ Throttle Cable
^ Throttle Valve