Knock Sensor Description (2.4L); Knock Sensor Removal And Installation (2.4L); Oxygen Sensor Description (2.4L); Operation - Chery Tiggo 2009 Service Manual

4. Installation is in the reverse order of removal.
CAUTION:
Before removing the coolant temperature sensor (for instrument cluster), release the coolant pres-
sure and make sure the engine is cold.
Knock Sensor
Description
The knock sensor is attached to the cylinder block. The knock sensor is designed to detect engine vibration that is
caused by detonation.

Operation

When the knock sensor detects a knock in one of the cylinders, it sends an input signal to the ECM. In response, the
ECM retards ignition timing for all cylinders by a scheduled amount.
Knock sensors contain a piezoelectric material which constantly vibrates and sends an input voltage (signal) to the
ECM while the engine operates. As the intensity of the vibration increases, the knock sensor output voltage also
increases.
The voltage signal produced by the knock sensor increases with the amplitude of vibration. The ECM receives an
input knock sensor voltage signal. If the signal rises above a predetermined level, the ECM will store that value in
memory and retard ignition timing to reduce engine knock. If the knock sensor voltage exceeds a present value, the
ECM retards ignition timing for all cylinders. It is not a selective cylinder retard.
The ECM ignores knock sensor input signal during engine idle conditions. Once the engine speed exceeds a spec-
ified value, knock retard is allowed.
Removal & Installation
1. Disconnect and isolate the negative battery cable.
2. Disconnect the knock sensor electrical connector.
3. Remove the knock sensor retaining bolt (1) and
remove the knock sensor.
(Tighten: Knock sensor retaining bolt to 20 N·m).
4. Installation is in the reverse order of removal.
Oxygen Sensor
Description
This vehicle is equipped with two oxygen sensors (upstream oxygen sensor & downstream oxygen sensor). The oxy-
gen sensors are located before and after the three way catalyst. The oxygen sensors continually monitor the oxygen
level in the exhaust gas. The sensor is made of ceramic zirconia. The zirconia generates voltage from approximately
1 volt in richer conditions to 0 volt in leaner conditions.
Operation
The O2 sensors produce voltages from 0 to 1 volt, depending upon the oxygen content of the exhaust gas. When a
large amount of oxygen is present (caused by a lean air/fuel mixture, can be caused by misfire and exhaust leaks),
the sensors produces a low voltage. When there is a lesser amount of oxygen present (caused by a rich air/fuel
mixture, can be caused by internal engine problems) it produces a higher voltage. By monitoring the oxygen content
and converting it to electrical voltage, the sensors act as a rich-lean switch.
Chery Automobile Co., Ltd.
ON-VEHICLE SERVICE
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LTSM030011
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