WS3 Ocilloscope Patterns

These sensors and actuators are used for the general lab worksheet WS3:
You need to capture at least 7 patterns from the lists below:
Sensors
MAP (digital)
MAF (digital)
TPS (switch type)
RPM (ac magnetic crank or distributor)
RPM (cam or distributor)
RPM (Hall digital crank or distributor)
Oxygen sensor
Actuators:
Injectors (petrol)
Injectors (diesel)
Idle air (digital 2 wire)
Idle air (digital 3 wire, both channels)
Ignition timing control (digital or analogue)
Ignition primary
Ground noise
Alternator ripple

Alternator Ripple

Signal Name: Alternator Ripple

Volt/division: 188mV

Time/division: 2.1ms

This above waveforms show the alternator ripple for idle and under load. With headlights , Air con, Radio ect on. The Alternator produces AC voltage and current . The battery requires DC voltage and current to charge properly. Diodes located within the alternator rectify the AC to DC. However, a small amount of AC can still be present and no harm is done. Problems can develop when alternator diode faults permit unacceptable amounts of AC to pass into the electrical systems.

Ignition Primary

Signal Name: Ignition Primary.

Volt/division: 20V

Time/division: 2ms


The beginning of the waveform is charging voltage. The Voltage then drops to 0V by the ECU/ Igniter. Next a Back EMF is caused which is 40V. Which is when the spark is created. Next is spark duration and coil oscillations and back to charging voltage.

Ground Circuit.

Signal Name: Ground Circuit

Volt/division: 0.5V

Time/division: 2ms

This shows a low amount of voltage in the earth circuit which in term means low resistance. Our voltage from the waveform was 0.006V which is very small. This is acceptable from the manufacturers specifications. Anything above 0.050V is considered excessive.

MAF sensor

Signal Name: MAF sensor

Volt/division: 2V

Time/division: 50ms

This waveform is showing MAF voltage when accelerator was pressed and released slowly to create this waveform. This shows as more air enters the engine there is a larger voltage produced.

MAP sensor

Signal Name: MAP Sensor

Volt/division: 2V

Time/division: 100ms

The beginning of this waveform was the MAP at idling voltage. When accelerator was pressed and released this waveform was created. This shows voltage is increased as more throttle is applied. The Map sensor produces a voltage created from the vacuum inside the intake manifold.The data is used to calculate air density and determine the engine's air mass flow rate, which in turn determines the required fuel metering for optimum combustion. At the end of the waveform it is back to idling voltage.
Secondary ignition pattern

Signal Name: Secondary Ignition

Volts/division: 4KV

Time/division: 3.4ms

This waveform is from the secondary ignition off a b16A integra.

The ignition secondary picture shown above in the waveform is a typical picture from an engine fitted with electronic ignition. The waveform is an individual secondary High Tension (HT) picture that can be observed one cylinder at a time.

The secondary waveform shows the voltage required to jump the plug's electrode (A), and (B) the length of time that the HT is flowing across the spark plug's electrode after its initial voltage to jump the plug gap. This time is referred to as either the ‘burn time’ or the ‘spark duration’.

In the illustration shown, it can be seen that the horizontal voltage line in the centre of the oscilloscope (C) is at fairly constant voltage of approximately 3 kV. This voltage is referred to as the Sparkline kV. This voltage is the voltage required to maintain the spark flow across the plug's electrode, and is determined primarily by the secondary resistance within the HT circuit. From the 0 ms point on the scope to point D is the spark duration, in this case around 1.0 milliseconds. The waveform is then seen to drop sharply into what is referred to as the ‘coil oscillation’ (E). The coil oscillation should display a minimum number of peaks (both upper and lower) and at least of 4 - 5 peaks should be seen. A loss of peaks on this oscillation shows that the coil needs substituting. An example of a faulty coil and the subsequent loss of oscillations can be seen in Fig 1.2. The oscillation seen at point (F) is called the ‘polarity peak’; this voltage will be of the opposite polarity to the plug firing voltage as this is created when the magnetic flux is initially built, or at the start of the dwell period.

http://www.pc-oscilloscopes.com/primary-vs-secondary.html

Magnetic Distributor.

Signal Name: RPM (Magnetic, Distributor)

Volt/division: 10V

Time/division: 10ms


This is the voltage created at idle. As frequency increases so does voltage and amplitude. If the engine RPM was increased voltage and amplitude would also be increased. This is AC voltage.This works with a magnet and a pick up coil. As the air gap/ distance from the magnet gets further away voltage gets lower and when it gets closer voltage gets higher. The engine will die if the ECU does not receive this signal.