Counter Pro Course #6
Fuel Injection #1
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The fuel injector. |
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To get into the airstream, fuel must be a mist, not a solid "squirt". The injector nozzle is
designed to take the high-pressure fuel flow and to turn the potential squirt into an actual
spray pattern. This spray must be misty enough to mix completely with the incoming air
and create an efficient burn within the engine cylinders.
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While nozzle types may look slightly different when closely examined, the final results of
injection should always be a fine, metered fuel mist at the instant injection occurs. If the
nozzle does not produce a fine, metered mist, something is wrong with the system and
poor driveability will result.
While injectors for both the mechanical and electronic system create a fine fuel mist, they
are different in several respects. We will describe these differences later.
| The control unit. |
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The control unit's basic job is to sense what mode the engine is in, its speed conditions and
the load of fuel the injection systems must supply. Using this data, the control unit must
tell the injector to inject a corresponding quantity of fuel into the intake airstream.
Although the control units of a mechanical system are completely different in nature from
an electronic system, they perform the exact same functions, such as regulating the delivery
of fuel to the injector so the air/fuel mixture is correct for all conditions of engine speed,
load and power demand.
The control unit receives a series of inputs, which communicates what is happening in and
around the engine. It then "calculates" what is being asked of it and sends the correct
signal to deliver the exact quantity of fuel to meet these needs.
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