Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 25

ELECTRONIC CONTROL SYSTEM - Air Flow Mete r
OPERATION AND FUNCTIO N
When air passes through the air flow meter from
the air cleaner, it pushes open the measuring
plate until the force acting on the measuring
plate is in equilibrium with the return spring .
The potentiometer, which is connected coaxially
with the measuring plate, converts the intake air
volume to a voltage signal (VS signal) which is
sent to the Engine ECU . The damping chamber
and compensation plate act to prevent the
measuring plate from vibrating when the air
intake volume changes suddenly .
Potentiometer
OHP 1 1
IDLE MIXTURE ADJUSTING SCRE W
An idle mixture adjusting screw is included in
the bypass passage . This screw is used to adjust
the volume of intake air which bypasses the
measuring plate, and can be used to adjust the
idle mixture . (Some engines are equipped with
air flow meters which are sealed with an
aluminum plug .)
®
REFERENCE
Standard Adjustment Mark of Idle Mixture
Adjusting Scre w
As shown in the illustration, a two digit
number is stamped on the air flow meter near
the idle mixture adjusting screw . This number
indicates the distance from the body upper
surface to the flat surface of the screw when
the VS voltage of the air flow meter is at the
standard voltage at the time that the volume
of air through the bypass was adjusted during
final inspection of the air flow meter at the
factory . For example, if the number is "30", it
means that the distance was 13 .0 mm (0 .511
in) . If the number is "26", it indicates the
distance was 12 .6 mm (0 .496 in) .
Air flow meter
Idle mixture
adjusting scre w
Idle mixture
adjusting screw
19