Fuel Injector - Subaru XT 1988 Service Manual

FUEL INJECTION SYSTEM
The difference in oxygen concentration changes greatly in the
1800
cc
model
vicinity of the optimum air-fuel ratio, and hence the change
in the electromotive force is also large. By inputting this
information into the MPFI control unit, the air-fuel ratio of
the supplied mixture can be determined easily. The O
2
sensor
does not generate much electromotive force when the tem-
perature is low. The characteristics of the electromotive force
stabilize at temperatures of approximately 300 to 400°C
(572 to 752°F).
Fig. 11
Large Theoretical air-fuel
ratio
To be judged
as rich
t
Comparison
- - - r . - - ___
vo_ltage
Small _ Air-fuel _ Large
Small
ratio
Fuel Injector
A21-224
A21-225
The fuel injector injects fuel according to the valve open
signal received from the MPF I control unit.
The nozzle is attached on the top of the fuel injector. The
needle valve is lifted by the solenoid coil through the plunger
on arrival of the valve open signal.
Since the injection opening, the lifted level of needle valve
and the regulator-controlled fuel pressure are kept constant,
the amount of fuel to be injected can be controlled only by
the valve open signal from the MPF I control unit.
At the fuel inlet of the injector, the filter is mou nted to pre-
vent dust from entering.
On the 2700 cc model, a high resistor is built into the fuel
injector to etim inate a separate dropping resistor.
Fig. 12
2700
cc
model
Fig. 13
9
2-7
Coil
L2-1469
L2-1470