Signal name: Crankshaft Position Sensor
Volt/division/range: 2v
Time/division/range: 20ms
1. At this point, the sensor is directly in between the crank teeth giving a neutral magnetic force, and thus reading 0v.2.As the next crank tooth approaches, the magnetic field starts to get stronger again, so the voltage reading starts to get stronger.
3. At this point the tooth is at its closest point with the sensor, and the magnetic field is at its strongest.
4. As the tooth continues rotating forward, it passes the sensor which sudddenly collapses the magnetic field, inducing a back EMF
If the sensor were damaged for any reason, or if it had faulty wiring or a bad ground connection, it wouldnt work properly. Also if there were any interference in the sensor lines, it could cause too much resistance, and therefore get an incorrect reading.
This is important because V=IxR. So if the resistance were too high, the voltage reading from the sensor would be far off what the actual reading should really be. The resistance could also be consuming so much voltage so the voltage reading could be far less than it actually is.
The blue line indicates what the readings may be if the sensor was faulty.As the voltage is very high, it could possibly be a only a short time before this sensor would open circuit.
Engine: Toyota 4A-FE
Signal name: Camshaft Position Sensor
Volt/division/range: 2v
Time/division/range: 50ms
The Cam position sensor is very similar to the crankshaft position sensor, so the tests will be similar also.
The Cam position sensor is very similar to the crankshaft position sensor, so the tests will be similar also.
1. At this point, the sensor is directly in between the cam teeth giving a neutral magnetic force, and thus reading 0v.2.As the next cam tooth approaches, the magnetic field starts to get stronger again, so the voltage reading starts to get stronger.
3. At this point the tooth is at its closest point with the sensor, and the magnetic field is at its strongest.
4. As the tooth continues rotating forward, it passes the sensor which sudddenly collapses the magnetic field, inducing a back EMF
If the sensor were damaged for any reason, or if it had faulty wiring or a bad ground connection, it wouldnt work properly. Also if there were any interference in the sensor lines, it could cause too much resistance, and therefore get an incorrect reading.
This is important because V=IxR. So if the resistance were too high, the voltage reading from the sensor would be far off what the actual reading should really be. The resistance could also be consuming so much voltage so the voltage reading could be far less than it actually is.
The blue line indicates what the readings may be if the sensor was faulty.
As the voltage is very low, it would send the wrong data to the ECU, which could induce more faults.
Engine: Toyota 4A-FE
Signal name: MAP sensor
Volt/division/range: 1v
Time/division/range: 500ms
a) Engine is idling. There is more vacuum so less voltage present. 1.8v.
b) Engine accelerating & drawing in more air so voltage starts to increase.
c) Voltage peaks and starts to decelerate.
d) Voltage drops even further as Manifold pressure increases.
e) Voltage returns to base voltage.
When the throttle opens up, the pressure inside the manifold is lost, and now has Lambda 1 or atmospheric pressure. Relying on the graph results, we see that the voltage on this MAP sensor increases as the pressure is lost, and voltage decreases as manifold pressure increases.
If there were a fault in this sensor, i.e: resistance in the signal wire etc. its possible that the voltage reading would become much lower than showed on the graph. A side effect of this would that the engine could be running leaner than needed.
Engine: Toyota 4A-FE
1. At 0.00v, the acceleration begins and voltage rises.
2. The voltage increases because as the engine accelerates the throttle opens and air is travelling through the air intake. Air passes through the MAF sensor cooling the hot wire, so the ECU inputs more current to the hot wire to keep its temperature.
3. As the engine decelerates, there is less air passing through the MAF sensor, so less current is needed to keep the hot wire hot.
This MAF sensor is working fine. If there were any problems with this sensor, there would be no voltage reading, or if there were too much resistance, the voltage reading would be lower than the actual reading, as indicated in the sensors before this.
a) Engine is idling. There is more vacuum so less voltage present. 1.8v.b) Engine accelerating & drawing in more air so voltage starts to increase.
c) Voltage peaks and starts to decelerate.
d) Voltage drops even further as Manifold pressure increases.
e) Voltage returns to base voltage.
When the throttle opens up, the pressure inside the manifold is lost, and now has Lambda 1 or atmospheric pressure. Relying on the graph results, we see that the voltage on this MAP sensor increases as the pressure is lost, and voltage decreases as manifold pressure increases.
If there were a fault in this sensor, i.e: resistance in the signal wire etc. its possible that the voltage reading would become much lower than showed on the graph. A side effect of this would that the engine could be running leaner than needed.
Engine: Toyota 4A-FE
Signal name: MAF sensor (analogue)
Volt/division/range: 1v
Time/division/range: 500ms
1. At 0.00v, the acceleration begins and voltage rises.2. The voltage increases because as the engine accelerates the throttle opens and air is travelling through the air intake. Air passes through the MAF sensor cooling the hot wire, so the ECU inputs more current to the hot wire to keep its temperature.
3. As the engine decelerates, there is less air passing through the MAF sensor, so less current is needed to keep the hot wire hot.
This MAF sensor is working fine. If there were any problems with this sensor, there would be no voltage reading, or if there were too much resistance, the voltage reading would be lower than the actual reading, as indicated in the sensors before this.
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