WS3 General lab Scope
We did this exercise on Toyota engine model 1ZZ
1.
Signal Name RPM (AC magnetic crank or distributor)
Volt/division/range 5V
Time/division/range 1mS
This is an alternating current waveform. At point A, the flywheel teeth moving toward the inductive crankshaft sensor and induce a positive voltage. At point B, the flywheel teeth is align with the inductive crankshaft sensor, thus the voltage drop down to 0V. At point C, the flywheel teeth is leaving the crankshaft sensor and induce s negative.
2.
Signal Name Oxygen Sensor
Volt/division/range 0.5V
Time/division/range 1S
This vehicle has a zirconla oxygen sensor. At point A, the oxygen sensor generate about 0.1V due to the oxygen level is high in the exhaust and did not combine with the fuel, this mean the air fuel mixture is lean. At point B, the voltage signal is about 0.9V, this mean there is a little unburned oxygen in the exhaust and air fuel mixture is rich.
With of close loop system, the oxygen sensor will generate waveform signal. This is due to the ECU will analyze the combustion process and emissions. Therefore, when ECU receive a lean signal (point A low voltage) from oxygen senor, it rich the fuel mixture and the oxygen sensor output voltage will do up to point B. At point B, oxygen sensor sense the mixture too rich and tell the ECU inject less fuel. This action keep continually to adjust the engine fueling and we have waveform signal.
3.
Signal Name Injector petrol
Volt/division/range 20V
Time/division/range 5mS
At point A, the injector is off, so we have supply voltage 12V. When the transistor receive the signal from the ECU and ground the injector or switch on the injector, the available voltage become 0V (negative trigger switch On), this action show at point B. When the ECU turn off the injector, magnetic field in the solenoid collapse and generate back EMF, this is show at point C. At point D show the peak voltage of the back EMF. Point E describe a supply voltage and the injector is in Off position. Point B also show the pulse width and period of an injector switch on ore grounded.
4.
Signal Name Ignition timing control
Volt/division/range 2V
Time/division/range 2mS
Ignition timing control is design to control the spark timing by sending out PWN signal to the ignition system to switch on and off the power transistor. At point A, this is 5V digital signal send from the ECU to the ignition system and activate or saturate the power transistor, then the primary coil is buiding up the magnetic field. At point B, these is no voltage signal send to ignition system, so the power transistor cut off, magnetic field surround the primary coil collapse and induced high voltage into secondary winding and create a spark to ignite the compressed air fuel mixture
1.
Signal Name RPM (AC magnetic crank or distributor)
Volt/division/range 5V
Time/division/range 1mS
This is an alternating current waveform. At point A, the flywheel teeth moving toward the inductive crankshaft sensor and induce a positive voltage. At point B, the flywheel teeth is align with the inductive crankshaft sensor, thus the voltage drop down to 0V. At point C, the flywheel teeth is leaving the crankshaft sensor and induce s negative.
2.
Signal Name Oxygen Sensor
Volt/division/range 0.5V
Time/division/range 1S
This vehicle has a zirconla oxygen sensor. At point A, the oxygen sensor generate about 0.1V due to the oxygen level is high in the exhaust and did not combine with the fuel, this mean the air fuel mixture is lean. At point B, the voltage signal is about 0.9V, this mean there is a little unburned oxygen in the exhaust and air fuel mixture is rich.
With of close loop system, the oxygen sensor will generate waveform signal. This is due to the ECU will analyze the combustion process and emissions. Therefore, when ECU receive a lean signal (point A low voltage) from oxygen senor, it rich the fuel mixture and the oxygen sensor output voltage will do up to point B. At point B, oxygen sensor sense the mixture too rich and tell the ECU inject less fuel. This action keep continually to adjust the engine fueling and we have waveform signal.
3.
Signal Name Injector petrol
Volt/division/range 20V
Time/division/range 5mS
At point A, the injector is off, so we have supply voltage 12V. When the transistor receive the signal from the ECU and ground the injector or switch on the injector, the available voltage become 0V (negative trigger switch On), this action show at point B. When the ECU turn off the injector, magnetic field in the solenoid collapse and generate back EMF, this is show at point C. At point D show the peak voltage of the back EMF. Point E describe a supply voltage and the injector is in Off position. Point B also show the pulse width and period of an injector switch on ore grounded.
4.
Signal Name Ignition timing control
Volt/division/range 2V
Time/division/range 2mS
Ignition timing control is design to control the spark timing by sending out PWN signal to the ignition system to switch on and off the power transistor. At point A, this is 5V digital signal send from the ECU to the ignition system and activate or saturate the power transistor, then the primary coil is buiding up the magnetic field. At point B, these is no voltage signal send to ignition system, so the power transistor cut off, magnetic field surround the primary coil collapse and induced high voltage into secondary winding and create a spark to ignite the compressed air fuel mixture
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