The EMS V8 includes two knock sensors (one per bank of cylinders), which are located in the collapse of the cylinder block. Sensors connect to ECM (the engine control unit) using twisted pair wires.
Knock sensors generate a voltage signal proportional to the level of mechanical vibration that occurs at the time of ignition. Each sensor monitors knocking in its own bank of cylinders.
The sensing element of the knock sensor is a piezoelectric element. When a piezoelectric element is deformed under the action of external forces, a potential difference arises on it. The piezoelectric element is affected by the force of mechanical vibrations in the material of the cylinder block, which occur during the combustion of the air-fuel mixture in the cylinders of a running engine. Knock sensor signals are sent to the ECM (the engine control unit) , where they are compared with the map data stored in memory. Based on ECM comparison (the engine control unit) determines the presence of detonation in each individual cylinder. When ECM knock is detected (the engine control unit) reduces the ignition timing for several working cycles, and then gradually returns to its original value.
Knock sensors require constant care, especially when removing and installing them. The requirements for surface preparation and tightening torque must be strictly observed. The tightening torque and the quality of the preparation of the sensor socket significantly affect the conductivity of sound waves from the cylinders to the piezoelectric element.
Combined with ECM camshaft position sensor signals (the engine control unit) uses knock sensor signals to determine the optimal ignition timing for each of the engine's cylinders. Ignition timing is selected from data cards stored in the ECM (the engine control unit). Default ECM (the engine control unit) uses ignition data cards for premium octane fuel (RON) 98. Once tuned, the engine can also be run on regular quality 91 octane fuel. If only low quality fuel is available or the owner decides to switch from quality to low grade gasoline, there will be signs of pre-ignition for a short period of time. Such short-term work with early ignition will not damage the engine. Signs of early ignition will be observed during the period that the ECM needs (the engine control unit) for training and correction of data maps in order to compensate for changes in fuel quality. This property is called adaptation. ECM block (the engine control unit) capable of adapting its fuel and ignition system control outputs according to multiple sensor inputs.
If the signal from any of the knock sensors becomes undefined, then the ECM (the engine control unit) stops using feedback in control (switches to open loop control). Under such circumstances eCm (the engine control unit) defaults to using the data card (adjustment characteristics of the ignition system) from your own memory. This measure protects the engine from damage when switching to low-grade fuel. Malfunction indicator lamp (MIL) does not turn on, however, under certain driving conditions, the driver may hear a characteristic "knock" engine and notice a decrease in engine power and smoothness of its operation.
Simultaneously with the ECM Knock Sensor DTC (the engine control unit) records engine parameters at the time the DTC was logged: engine speed, engine load, and coolant temperature.
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