WS3 General Lab Scope

General Lab Scope Worksheet    

1. Throttle Position Sensor (TPS)

Signal Name : TPS

Volt/division/range : 2 v
 
Time/division/range : 500 ms

Trigger notes

Probe used : A black probe of the lab scope is touched the earth and a red probe is connected the TPS voltage on the signal panel.

Draw the pattern below:

Explain the operation of the sensor or device using the Graph:
(Use arrows at different points, and describe what happens there)
  
Position 1 : When the throttle was closed, the voltage was at 0.407 v. 
Position 2 : The voltage increased to 3.796 v when the throttle was opening.
Position 3 : The voltage was the highest at 3.796v while the throttle was widely opened.
Position 4 : When the throttle was closing, the voltage dropped to 0.407 v which is same as position 1 value with the completely closed throttle position.

2. Vacuum sensor

Signal Name : Vacuum sensor

Volt/division/range : 1 v
 
Time/division/range : 1 s
 
Trigger notes

Probe used : A black probe of the lab scope is touched the earth and a red probe is connected the vacuum sensor voltage on the signal panel.
 
Draw the pattern below:

Explain the operation of the sensor or device using the Graph:
(Use arrows at different points, and describe what happens there)

  From the vacuum sensor, when the engine is idling, the manifold vacuum is highly produced and the sensor creates lower voltage at 1.386 v, at position 1. When the acceleration goes up, manifold vacuum is lower with higher voltage of 3.431 v, at position 2. On the other hand, form deceleration, the manifold vacuum increases again with lower voltage just under 1.386 v. This is due to the throttle body closed, the engine decelerates which creates a lower pressure and higher vacuum at position 3 and 4. I can see the vacuum stability at position 5 which back to its original voltage at idling. 

3. Air Temperature Sensor
Signal Name : Air Temperature Sensor

Volt/division/range : 1 v

Time/division/range : 5 s

Trigger notes

Probe used : A black probe of the lab scope is touched the earth and a red probe is connected the air temperature sensor voltage on the signal panel.

Draw the pattern below:

Explain the operation of the sensor or device using the Graph:
(Use arrows at different points, and describe what happens there)

  At position 1, the air temperature sensor produces at 1.014 v when the engine is running with normal air temperature. And then, when the heat is added by an heat gun in the intake air, the voltage decreased gradually to 0.832 v, at position 2. When the heat gun is turned off, the voltage increased gradually to near 1.014 due to cool intake air, at point 3. As a result, the air temperature sensor creates higher voltages when the air is cold. On the other hand, when the air is hot, the sensor creates lower voltages.
4. Injector

Signal Name : Injector 

Volt/division/range : 20 v

Time/division/range : 5 ms

Trigger notes

Probe used : A black probe of the lab scope is touched the earth and a red probe is connected the injectors voltage on the signal panel.
Draw the pattern below:

Explain the operation of the sensor or device using the Graph:
(Use arrows at different points, and describe what happens there)

  The engine is idling. At position 1, 13 v is supplied for injector's operation. When the ECU is grounded, the injector with the generation of magnetic field is opened for around 3ms of fuel injection and the the voltage decreased to almost 0 v, at position 2. At position 3, when the ECU gives injector's switching for cutting the fuel injection, the magnetic field is collapsed with peak voltage. And then, the voltage goes back to the original state at around 13 v, at position 4.   
5. RPM Sensor

Signal Name : cam position sensor and crank position sensor

Volt/division/range :  A=2 v (cam), B=5 v(crank)

Time/division/range : 20 ms

Trigger notes

Probe used : A black probe of the lab scope is touched the earth and a red probe (A) is connected the cam signal and another red probe (B) is touched the crank signal on the signal panel.
Draw the pattern below:

Explain the operation of the sensor or device using the Graph:
(Use arrows at different points, and describe what happens there) A= Cam position sensor, B= Crank position sensor
A good magnetic crank position sensor should produce an alternating current(AC) when the engine is cranked. Higher RPM produces higher voltage and frequency also increases. Defective crank and cam sensors voltage to low. So proper output voltage is critical for appropriate engine operation.