Manifold absolute pressure sensor (IDA)
The location of the elements of the fuel system in a car with engines of 1.6 liters and 1.8 / 2.0 liters
1 - absolute pressure sensor in the intake manifold (IDA); 2 - intake air temperature sensor (IAT); 3 - coolant temperature sensor (EATING); 4 - throttle position sensor (TPS); 5 - camshaft position sensor (CMP); 6 - crankshaft angle sensor (CKP); 7 - heated oxygen sensor; 8 - nozzles; 9 - idle speed modulator (ISA); 10 - vehicle speed sensor (VSS); 11 - knock sensor; 12 - blocking switch; 13 - ignition switch; 14 - ECM; 15 - air conditioner compressor relay; 16 - solenoid valve of the fuel vapor recovery system (PCSV); 17 - control relay; 18 - ignition coil; 19 - diagnostic connector
1 - absolute pressure sensor in the intake manifold (IDA); 2 - intake air temperature sensor (IAT); 3 - coolant temperature sensor (EATING); 4 - throttle position sensor (TPS); 5 - camshaft position sensor (CMP); 6 - crankshaft angle sensor (CKP); 7 - heated oxygen sensor; 8 - nozzles; 9 - idle speed modulator (ISA); 10 - vehicle speed sensor (VSS); 11 - knock sensor; 12 - blocking switch; 13 - ignition switch; 14 - ECM; 15 - air conditioner compressor relay; 16 - solenoid valve of the fuel vapor recovery system (PCSV); 17 - control relay; 18 - ignition coil; 19 - diagnostic connector
1 - absolute pressure sensor in the intake manifold (IDA); 2 - intake air temperature sensor (IAT); 3 - coolant temperature sensor (EATING); 4 - throttle position sensor (TPS); 5 - camshaft position sensor (CMP); 6 - crankshaft angle sensor (CKP); 7 - heated oxygen sensor; 8 - nozzles; 9 - idle speed modulator (ISA); 10 - vehicle speed sensor (VSS); 11 - knock sensor; 12 - blocking switch; 13 - ignition lock; 14 - ECM; 15 - air conditioner compressor relay; 16 - solenoid valve of the fuel vapor recovery system (PCSV); 17 - control relay; 18 - ignition coil; 19 - diagnostic socket
The intake manifold absolute pressure sensor is a sensitive variable resistor. It measures intake manifold pressure, which varies with engine operating conditions and is converted into voltage.
The sensor is also used to measure atmospheric pressure when starting the engine and provides engine operation modes at different altitudes. The sensor is powered by a voltage of 5 V. Based on information from the sensor, the engine control unit regulates the amount of fuel supplied to the engine, and also changes the ignition timing.
Examination
1. Connect a voltmeter between terminals 1 and 4 of the MAP sensor connector.
- Contact 1: «Weight»
- Pin 4: Positive voltage
2. Measure the voltage.
- Output voltage with the ignition on and the engine off: 4-5 V
- Output voltage at idle frequency: 0.5-2.0V
3. If the output voltage of the sensor differs from the required one, replace the sensor.
Intake air temperature sensor (IAT)
The intake air temperature sensor is built into the absolute pressure sensor and is a thermistor whose resistance changes with temperature. The ECM takes into account the sensor signal and adjusts the pulse width applied to the injectors, resulting in a change in the amount of fuel supplied to the engine cylinders.
Sensor test
1. Measure the resistance between terminals 3 and 4 of the sensor connector.
Temperature | Resistance, kOhm |
0°C | 4,5–7,5 |
20°C | 2,0–3,0 |
40°C | 0,7–1,6 |
80°C | 0,2–0,4 |
2. If the sensor resistance is out of specification, replace the sensor.
Coolant temperature sensor (ECT)
The coolant temperature sensor is located in the cylinder head and monitors the coolant temperature and sends a signal to the ECM. A thermistor is used as a sensor, which is sensitive to temperature changes. The electrical resistance of the thermistor decreases as the temperature increases.
When the engine is cold, the ECM operates in open loop mode, which results in a richer air-fuel mixture entering the engine cylinders and increasing the idle speed. This continues until the engine reaches normal operating temperature.
Examination
1. Remove the sensor from the intake manifold.
2. While heating the vessel with water and the sensor located in it, check its resistance.
Temperature | Resistance, kOhm |
–30°C | 22,22–31,78 |
–10°C | 8,16–10,74 |
0°C | 5,18–6,60 |
20°C | 2,27–2,73 |
40°C | 1,59–1,281 |
60°C | 0,538–0,650 |
80°C | 0,298–0,322 |
90°C | 0,219–0,243 |
3. If the resistance of the sensor differs from the required one, replace the sensor.
Installation
1. Apply LOCTITE 962T or equivalent to the sensor threads.
2. Screw in the sensor and tighten to specification. Tightening torque: 15–20 Nm.
3. Connect the connector to the sensor.
Throttle position sensor (TP)
The throttle position sensor is a variable resistor that rotates with the throttle shaft and provides information from which the ECM determines when the throttle is closed, wide open, or in between positions.
The sensor is rigidly connected to the throttle shaft. Depending on the position of the throttle valve, the resistance of the sensor changes.
Examination
1. Disconnect the connector from the throttle position sensor.
2. Measure the resistance between terminals 2 (weight) and 3 (nutrition) sensor connector. Resistance: 0.7-3.0 kOhm.
3. Connect an ohmmeter to terminals 2 (weight) and 3 (sensor output) sensor connector.
4. Slowly open the throttle and check that the sensor resistance changes smoothly in proportion to the throttle opening.
5. If the resistance of the sensor differs from the required one or changes abruptly, replace the sensor. Tightening torque: 1.5–2.5 Nm.
Camshaft position sensor (CMP)
The camshaft position sensor generates pulses at TDC of the first cylinder on the compression stroke, on the basis of which the ECM calculates the sequence of the fuel injection system.
Crank angle sensor (CKP)
The crank angle sensor consists of a magnet and a coil and is located near the flywheel ring gear. The sensor sends information to the ECM about the angle of rotation of the crankshaft (piston position). Based on the output signal information from this sensor, the ECM calculates engine speed and crankshaft position.
Examination (1.6 L I4)
1. Disconnect the connector from the crank angle sensor.
2. Measure the resistance between pins 1 and 2 of the sensor connector. Resistance: 0.486-0.594 kOhm at 20°C.
3. If the resistance of the sensor differs from the required one, replace the sensor. Gap between rotor and crankshaft angle sensor: 0.5–1.5 mm Tightening torque: 9–11 Nm.
Heated oxygen sensor (HO2S)
The heated oxygen sensor detects the oxygen concentration in the exhaust gases and converts it into a voltage that it sends to the ECM.
The sensor output voltage is 500 mV if the fuel mixture is richer than the theoretical one, and the voltage is 100 mV if the fuel mixture is leaner (higher oxygen concentration in the exhaust gases). Based on this data, the engine control unit changes the fuel ratio in the air-fuel mixture.
Examination
- 1. Before checking, warm up the engine until the coolant temperature is 80-95°C.
- 2. Use an accurate digital voltmeter to measure the output voltage of the sensor.
1. Disconnect the connector from the oxygen sensor and connect a voltmeter to the oxygen sensor connector.
2. By changing the engine speed, measure the output voltage of the oxygen sensor. If the sensor output voltage is not as specified, replace the sensor. Tightening torque: 50–60 Nm.