Chery A11 2003 - M7.9.7 EFI System; Intake Pressure and Intake Air Temperature Sensor

Maintenance Manual for Chery·Windcloud M7.9.7 EFI System
Chapter One: Operating Principle for
EFI Control and Execute Components
1. Intake Pressure and Intake Air
Temperature Sensor
Purpose: detects manifold absolute pressure
from
0.1~0.2bar and intake air temperature,
provides engine with load information.
Composition and principle: this sensor is
composed of two different sensors (i.e.
manifold absolute pressure sensor and intake
temperature sensor), and is installed above
pressurizer.
Pressure-sensitive element inside intake
pressure sensor detects pressure signal on
intake manifold for injection pulse width
control of EFI system. This sensor also
serves as the substitute of load signal sensor.
Intake air temperature sensing element is
a resistor of negative temperature coefficient
(NTC), which is similar to water
temperature sensor with resistance value
decreasing with the increasing of intake air
temperature. And engine ECU monitors the
variation of intake air temperature via a
comparison circuit inside.
Failure diagnosis: The electronic device
next to intake pressure sensor detects sensor
circuit troubles such as open circuit, short
circuit and sensor damages, etc. In case
ECU detects any sensor output signal that
goes beyond output characteristic curve, the
sensor is diagnosed as failed by ECU. For
example: when intake pressure is higher
than upper limit or lower than lower limit,
ECU detects sensor failure (in case that
intake pressure is lower than lower limit
when starting, ECU is able to recognize the
starting condition), and the engine fault
indicating lamp goes on. Under this
condition the engine works in failure mode.
Installation: to be installed on pressurizer.
Troubleshooting: mainly check if there is
short circuit or open circuit on the
connection between 4 lines on senosr and
ECU.
If there is short circuit, open circuit or
grounding between sensor wire harnesses.
Manifold absolute pressure /intake air temperature sensor
Manifold absolute
p
ressure and intake ai
r
tem
p
erature senso
r
Circuit diagram of manifold absolute pressure and intake
air temperature sensor
Pins: 1# is grounded (connecting ECU 17#);
2# outputs temperature signal
(connecting ECU 40#);
3# connects with standard 5V power
source (connecting ECU 33#);
4# outputs pressure signal (connecting
ECU 37#).
Sectional view of intake pressure and intake air
temperature sensor
1 Seal ring 5 Casing
2 Stainless steel bushing 6 Pressure bracket
3 PCB 7 Welded joint
4 Sensing element 8 Bonded joint
1