Computers and Control Systems: Description and Operation

Fuel Injection System Schematic:

The Computerized Engine Controls (CEC) electronically regulate the air/fuel ratio, idle speed, turbo boost pressure and ignition timing. This is done by three Electronic Control Units (ECU), one controlling the fuel injection system, one controlling the ignition and the other one controlling the turbo boost system.

FUEL INJECTION SYSTEM (BOSCH LH2.2-JETRONIC):

BOSCH LH2.2-JETRONIC stands for:

BOSCH = manufacturer
L = luft (German for air)
H = heiss (German for hot as in hot-wire)
2.2 = model series

This fuel injection is based on the Bosch multi-point fuel injection system with hot-wire air mass meter (LH-Jetronic). The ECU uses electrical input signals from various devices and sensors to calculate the engine load and condition. With this information it will adjust the injector frequency to provide optimal air/fuel mixture, performance, driveability and emissions output.

Input devices (the ECU receives):

^ Ignition switch signal.
^ Oxygen sensor (lambda sond) signal.
^ Engine speed (RPM) signal from the ignition control unit.
^ Knock signal from the ignition control unit.
^ Coolant temperature signal.
^ Air mass meter signal.
^ Throttle position signal.
^ A/C control signal from climate control ECU.
^ Turbo over-boost pressure signal.

Output devices (The ECU controls):

^ [1][2]System relay ground.
^ Suppressor relay via the [1][2]system relay.
^ Ballast resistor.
^ Fuel injector ground.
^ Idle air valve.
^ Air mass meter signal to the ignition system control unit (ignition ECU input device).
^ Shift indicator light.

Ignition System Schematic:

IGNITION SYSTEM (BOSCH EZ117K):

BOSCH EZ117K stands for:

BOSCH = manufacturer
E = elektronische (German for electronic)
Z = zuendung (German for ignition)
117 = model series
K = klopfregelung (German for knock control)

This ignition is based on the fully electronically controlled Bosch hall-effect ignition system with knock control (EZ-K). The ECU uses electrical input signals from various devices and sensors to calculate the engine load and condition. With this information the ECU will adjust the ignition timing to provide optimal performance, driveability and emissions output.

Input devices (the ECU receives):

^ Ignition switch signal.
^ Crankshaft position and speed (hall-effect) signal.
^ Knock signal.
^ Air mass meter signal from fuel injection control unit.
^ Throttle position signal.

Output devices (The ECU controls):

^ Power stage.
^ Engine speed signal to the fuel injection control unit (fuel injection ECU input device).
^ Knock signal to the fuel injection and turbo boost control unit (fuel injection or turbo boost ECU input device).
^ Crankshaft position and speed (hall-effect) sensor power supply (12V).

Turbo Boost System:

TURBO BOOST SYSTEM:

The turbo boost system increases the boost pressure during full throttle operation. This results in an additional 15 bhp at 5500 RPM.
The turbo boost is electronically controlled by a turbo boost ECU. The ECU uses various input devices to determine the control signal to the control valve. This control valve will regulate the turbo charger wastegate (turbo boost pressure) for optimal performance.

Input devices (the ECU receives):

^ Turbo boost relay (battery voltage).
^ Engine speed signal.
^ Throttle position signal.
^ Knock signal from ignition ECU.

Output device (The ECU controls):

^ Control valve ground.