1.2L REVOTRON ENGINE 157 IV. Knock Sensor : Component Details : Knock Sensor consists of a piezoelectric element. Piezoelectric elements generate voltage when vibration or pressure is applied to them. The Piezoelectric element in the knock sensor is tuned to the Engine Knock Frequency. Component Location : The knock sensor is mounted on the cylinder block. Preliminary Checks : 1. Faulty Knock Sensor 2. Check for P0327-11, P0328-12 - Improper Wiring Harness Connections between Knock Sensor and EMS ECU. Connector View : Connector Details: Connector Description 1 Signal 2 Ground Component Specification : The knock sensor provides input to ECU based on the vibration generated by 'knocking', which will enable ECU to limit ignition timing (Advance) for optimum efficiency. The knocking is the vibration generated due to uncontrolled combustion, due to which a charge transfer occurs in the sensor and as a result voltage is generated which is transmitted to ECU. The knock sensor is mounted on the cylinder block. Application of Knock Sensor : A piezo sensitive knock sensor with linear characteristic is mounted on the engine block. It transforms the structure borne vibrations into electrical signals which can be evaluated by the engine's ECU. The knock sensor signal is evaluated according to intensity and spectral information of knocking and non-knocking combustions. As a consequence the ignition parameter will be adjusted for the next combustions. Temperature Range: -400C to +1800C Mechanical & Electrical Characteristics : Main resonance frequency of Sensor head: > 30 kHz Up to 30 kHz the sensitivity must not exceed 200 mV/g. Capacitance (of sensor head): C = 1150 ± 200 pF Capacitance measured at frequency 1 kHz, parallel; sensor mounted with torque 20±5Nm. Due to parallel circuit of both sensor head and wire capacitance only the total capacitance can be measured. Temperature dependence of capacitance, related to 200C room temperature. For temperature -400C... + 200C≤ 1.9 pF/K For temperatures +200C ... + 1500C ≤ 3,3 pF/K Shunt resistor : 4.9MΩ ± 20% After ageing : 4-10MΩ (resistance between 2 signal leads) Resistor Pin for supporting sleeve > 1MΩ Temperature dependence of sensitivity at 9 kHz ≤ -0.04 mV/(g*K)
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