Ignition System: Description and Operation

Ignition System Schematic:

IGNITION SYSTEM (BOSCH EZ116K):

BOSCH EZ116K stands for:

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

This ignition is based on the fully electronically controlled Bosch 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):

^ Battery supply signal (voltage).
^ Ignition switch signal.
^ Crankshaft position and speed signal.
^ Knock signal.
^ Coolant temperature signal.
^ Air mass meter signal from fuel injection control unit.
^ Throttle position signal.
^ EGR temperature sensor signal (Calif. only).

Output devices (The ECU controls):

^ Power stage.
^ Crankshaft speed (RPM) signal to the fuel injection control unit (fuel injection ECU input device).
^ Crankshaft position signal to the fuel injection control unit (fuel injection ECU input device).
^ Knock signal to the fuel injection control unit (fuel injection ECU input device).
^ Diagnostic socket fault information.
^ EGR converter ground.
^ "CHECK ENGINE" light.
^ EGR converter (Calif. only).

If the self diagnostic circuit ("on board diagnostics") in the ECU detects a fault in the ignition system, it will activate the "CHECK ENGINE" light. By extracting the fault codes from the diagnostic socket, you can determine what component or components need further testing or replacement (see DIAGNOSIS AND TESTING PROCEDURES). The system can store up to three fault codes.

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.