Computers and Control Systems: Description and Operation

Motronic System Overview:

PURPOSE
The Bosch Motronic 2.9 engine control system provides precise control of the fuel injection and ignition systems to ensure optimum performance and strict emissions compliance.

OPERATION
Various engine sensors supply the Control Module with operating information. The Control Module processes sensor input and sends output signals to adjust injector pulse width, injector timing, idle speed, and ignition timing.

Motronic Inputs And Outputs:

Input sensors:
- Engine Coolant Temperature Sensor
- Crankshaft Position Sensor
- Camshaft Position Sensor
- EGR Temperature Sensor (except Corrado Federal)
- Intake Air Temperature Sensor
- Knock Sensors
- Mass Air Flow Sensor
- Heated Oxygen Sensor
- Throttle Position Sensor

Output actuators:
- EGR Frequency Valve (except Corrado Federal)
- Evaporative Emissions Frequency Valve
- Fuel Injectors
- Fuel Pump
- Ignition Coils for the Distributorless Ignition System
- Idle Air Control Valve
- Malfunction Indicator Lamp
- Secondary Air Injection Inlet Valve
- Secondary Air Injection Pump Motor

ADAPTIVE CONTROL
The Engine Control Module has adaptive idle speed, throttle position, and air/fuel mixture capabilities. The Control Module continuously compares the programmed data, for idle control and air fuel mixture, with the input values.

If a deviation occurs, the new input values are superimposed and stored in the programmed data map. As a result, new output signals are sent to the idle control valve, and or to the injectors. This allows the Engine Control Module to correct the idle speed, or injector pulse width for break-in wear or slight air leaks which might occur in the systems.

If power is interrupted to the Control Module, new adaptation takes place within several minutes of engine operation.