MANUALS · FUEL [13] · страница 220 из 340 · Открыть оригинал PDF ↗

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FUEL PUMP INSPECTION
Refer to P.13-15.

ENGINE CONTROL RELAY INSPECTION

Refer to P.13-100.

AIR FLOW' SENSOR

OPERATION

The air-flow sensor is incorporated within the
cleaner; it functions to convert the amount of
engineairintaketo pulse signalsoffre-
quency proportional to the amount of engine
air intake,andto input those signals tothe
engine control unit.
Theenginecontrolunit then,basedupon
those signals, calculatestheamount of fuel
injection, etc_

The power for the air flow sensor is supplied
from the control relay to the air flow sensor,
andisearthedattheenginecontrolunit.
The air flow sensor, by intermitting the flow
oftheSV voltage applied fromtheengine
control unit produces pulse signals_

Hint 1:

If the engine sometimes stalls, try starting the engine
and shaking the air flow sensor harness
If the engine then stalls, incorrect or improper contact
of the air flow sensor connector is the probable cause

Hint 2

If, when the ignition switch is switched ON (but the
engine isnot started) ,the air flowsensor output
frequency is any value other than zero, a malfunction
of the air flow sensor or of the engine control unit is
the probable cause.
Hint 3:

idlingis possible even though the air flow sensor
output frequency is deviated from the standard value
the cause is usually a malfunction other than of the air
flow sensor:

[Examples]

(1) Theflowofairwithintheair flowsensoris
disturbed: (Air duct disconnectionor clogged air
cleaner element )

(21 Incomplete combustionwithincylinder.(Mal-
functionofspark plugs, ignitioncoil,injectors,
compression pressure, etc )

(3)Air istakeninto the intakemanifold through
leaking gasket, etc.

(4)EGR valve

Improper adhesion of valve sheet

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