The object of all of the systems is to maintain the optimum air/ fuel mixture, which is chemically correct for theoretically complete combustion.

The stoichiometric ratio is 14.7 :1 (air to fuel).

Fuel inlet system.

Idle system.

Power enrichment system.

Main metering system.

Cold start system.

Dictate a more exact control of the engine air/fuel mixture

It generates an electrical signal and sends it to the computer

The need for Better fuel economy The increasingly strict emission control regulations

These systems operate in the following manner:

The oxygen sensor, installed in the exhaust manifold upstream of the catalytic converter, reads the oxygen content of the exhaust- gases.

The computer then decides how to adjust the mixture to. keep it at the correct air/fuel ratio.

(-)(-)

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RICH MIXTURE

AMOUNT OF OXYGEN

IN EXHAUST. LOW

HIGH SENSOR VOLTAGE

FREQUENCY VALVE

OPEN\CLOSE RATIO

DECREASING

PRESSURE UNDER DIAPHRAM

INCREASING

LEAN MIXTURE

AMOUNT OF OXYGEN

IN EXHAUST .HIGH

LOW SENSOR VOLTAGE

FREQUENCY VALVE

OPEN\CLOSE RATIO

INCREASING

PRESSURE UNDER DIAPHRAM

DECREASING

ENGINE EXHAUST

OXYGEN SENSOR

CATALYTIC CONVERTER

ELECTRONIC CONTROL UNIT

THROTTLE BODY

PRESSURE REGULATOR

FILTER

FUEL TANK

RETURN LINE

FUEL CONTROL SYSTEM

E.S

V.S E.

T

M.P

Conventional Ignition

System is triggered by contact breakers

The ignition coil is switched on and off mechanically

Synchronization with the crankshaft

The vacuum advance mechanism adjusts the ignition timing in relationship to engine load.

The centrifugal advance mechanism adjusts the ignition timing in relation to engine speed.

Transistorised Ignition

Triggering is done by transistors.

Ignition advance is the same as for the conventional.

There is no mechanical advance system in the distributor.

Engine speed and proximity sensor is used to trigger the ignition.

The E.C.U. computes the required ignition point and modifies the output signal.

Fully programmed Electronic Ignition

Fully programmed Electronic Ignition

An ignition advance map is written into the E.C.U.

It permits the best ignition point for any engine speed and load.

STATIC IGNITION

Static Ignition

The Static Ignition performs the same functions as the programmed system but has no rotating H.T. distribution system.

A four spark ignition coil is used instead of an ignition distributor

Static Ignition

Static Ignition

The two coils, within the four-spark ignition, are energised alternately via the E.C.U.

The respective coil generates two sparks simultaneously

One fires on the power stroke of the cylinder The other at the end of the exhaust stroke of the cylinder.

Ignition output stage, at the correct point for a given cylinder, determined by the E.C.U. ignition map

CIRCUIT DIAGRAM

CIRCUIT DIAGRAM

COIL RESISTANCE

COIL RESISTANCE

The Motronic fuel injection system combines the digital control of individual systems such as fuel injection and ignition into a single unit.

From the inputs engine speed (rpm), crankshaft position and temperature (engine and ambient air)) the control unit determines the ideal spark advance and fuel quantity

In this manner, spark advance and fuel quantity is tailored exactly to the engine operating conditions such as idling, part load, full load, warm up, deceleration and transient modes.

SEMULTANEOUS INJECTION

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SEMI-SEQUENTIAL INJECTION

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SEQUENTIAL INJECTION

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