8 - 5M - 2

TO IGNITION

PICK-UP DISTRIBUTOR

SPARK CONTROL COMPUTER

VACUUM TRANSDUCER

COOLANT TEMPERATURE SWITCH

IGNITION COIL

Fig. I-Typical Electronic Lean Bum (E.L.B.) System

GENERAL INFORMATION

The "Electronic Lean Bum System" (Fig. 1) consists of a "Spark Control Computer," various engine sensors, and a specially calibrated carburettor. The function of the system is to provide a means by which the engine can bum a lean air fuel mixture.

Spark Control Computer

The "Spark Control Computer" (Fig. 2) is the heart of the entire system. It gives that capability of igniting a lean fuel mixture according to different modes of engine operation by delivering an infinite amount of variable advance curves. The computer consists of one electronic printed circuit board, which simultaneously receives signals from all the sensors and within milliseconds computes them to determine engine operation and then advance or retard the ignition timing.

In other words, the computer determines the exact instant ignition is required; and then feeds the ignition coil to produce the electrical impulses which fire the spark plugs. It must be understood that this advancing and retarding of the ignition timing is not based on a constant curve. As mentioned before, the curves can be infinite and variable.

VACUUM TRANSDUCER

Fig. 2-Spark control computer (S.C.C.)

Sensors

There are six sensors on the engine which supply the "Spark Control Computer" with the necessary information needed to fire the spark plugs at the right time. They, and their functions, are as follows:

ISSUED OCT. '78