Repair Manual

IGNITION AND INJECTION
17
17 - 6
INJECTOR
The injector (drawing 4) is placed above the valve in order to ensure an optimal supply
and homogenous mixture of the fuel. The injector basic function is to ensure a very fine
and homogenous spraying of the fuel, shaped as a conic jet. This fuel is sprayed through
the half-moon gap between the valve and the wall, without hitting the latter, as it happens
in case of a straight spraying (carburetor).
For an exact dosing of fuel quantity we use the light component of the injector (its
moving needle), which ensures a rapid movement. Being permanently washed in fuel, it
avoids its heating and the fuel bubbles.
The electronic unit (pin 35) controls the injector functioning.
The injection time (t
i
) is the while the injector is opened and it is the most important
value of the injection system.
The injection time (t
i
) depends upon the voltage accumulator battery; if there are
voltage fluctuations during the functioning, the electronic control unit will correct the
injection time for an air-fuel optimal report (ë = 1).
In case of a low voltage at start the value (t
i
) should be increased in order to compensate
the lower flow of the fuel electric pump.
The simple testing of the injector is done by means of stroboscopic lamp. The air pipe
above the injection unit is to be dismounted, the engine is to be started and the spraying
cone of the fuel is watched by means of the stroboscopic lamp. The upper part (hydraulic
part) of the injection central unit is not to be repaired – the whole injector-valve-body
system is to be replaced.
In case of damaging the injector or the air sensor T, both of them are to be replaced.
The connector between the air sensor T and
the injector has the following connections:
1 - Air sensor T ( pin 13 computer )
2 - Injector supply ( + )
3 - Injector control ( pin 35 computer )
4 - Mass ( pin 27 computer )
The oscilloscope checks the injector
functioning; it is to be connected according
to the position “A”, namely mass parallel. It
is not to be connected as in position “B”,
which will affect the transistor, leading to
errors of signal.
+ APC
DESCRIPTION OF THE SYSTEM
vnx.su