ELECTRONIC CONTROL SYSTEM
- Manifold Pressure Sensor (Vacuum Sensor
)
MANIFOLD PRESSURE SENSOR
(VACUUM SENSOR
)
The manifold pressure sensor is used with D-
type EFI for sensing the intake manifold
pressure
.
This is one of the most important sensors in D-
type EFI
.
By means of an IC built into this sensor, the
manifold pressure sensor senses the intake
manifold pressure as a PIM signal
. The Engine
ECU then determines the basic injection duration
and basic ignition advance angle on the basis of
this PIM signal
.
Intake manifold pressure
OHP 9
A change in the intake manifold pressure causes
the shape of the silicon chip to change, and the
resistance value of the chip fluctuates in
accordance with the degree of deformation
.
This fluctuation in the resistance value is
converted to a voltage signal by the IC built into
the sensor and is then sent to the Engine ECU
from the PIM terminal as an intake manifold
pressure signal
. The VC terminal of the Engine
ECU supplies a constant 5 volts as a power
source for the IC
.
(V)
4
~
rn
3
OHP
9
f
Intake manifold pressur
e
OPERATION AND FUNCTION
OHP
9
A silicon chip combined with a vacuum chamber
maintained at a predetermined vacuum is
incorporated into the sensor unit
. One side of
the chip is exposed to intake manifold pressure
and the other side is exposed to the internal
vacuum chamber
.
Engine EC
U
0 20 60 100 kPa (abs)
(760, 29
.9) (610, 24
.0) (310,
1
2
.2)
(10, 0
.4) (mmHg
,
in
.Hg
Intake manifold pressure
[vacuum]
)
ELECTRICAL CIRCUITR
Y
Manifold pressure
sensor
1
5
V
R
IC
VC
PI
M
E2
E
l
To intake manifol
d
Silicon chip
/
OHP 10
17
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