WS2    Flash Codes

Warning: Be careful working around engines and exercise caution to avoid injury.

Note: The engine check light must be working.

If you have problems with the task, see you lecturer for help.

1. Flash/Blink Codes

1.1         Find a engine/vehicle that you have the workshop manual with the correct procedure and codes to diagnose the flash codes

1.2         Have your tutor create a fault in the EFI system

1.3         Using the workshop manual follow the procedure to extract the codes, explain briefly what is the procedure

 Firstly, When the ignition swith is turned on, the check engine light should light up then the engine is started, the light should turn off. Secondly, If the faults are found the diagnostic plug should open and connect between TE1 and E1. Thirdly, the ignition swith is turned on, the check engine light should flash according to fault codes. If the TPS has a fault, the light will flash four times and the light will turn off for a little while. And then, the light will turn on one time for second fault code. Next, I can check the fault codes from the manufacturer specification and I also find out other problems. The fault codes should be clear, after I repair the faults. Finally, the fault codes should be rechecked. When the E1 and TE1 of diagnosis box are connected, the check engine light should continueously flash under normal conditions.   

2              Trouble Codes or Fault Codes

2.1         Find where the Codes are listed

2.2         Record any codes, and what system and condition they describe in the chart below (Example: might be code number 21, for Throttle Position Sensor, signal voltage too low)

Code number	System affected	Condition described
22	Water Temperature Sensor	The voltage is high and does not move.
41	TPS	No voltages
31	Vacuum Sensor	The voltage is high and does not move.
24	Intake Air Temperature Sensor	The voltage is too low and does not move.

3             Visual Inspection to find fault

3.1         Do a visual inspection under the bonnet to find where the problem is. Use information from the code to know where to look for the problem and what type of problem to look for.

3.2         Describe the problem(s) you found:

 Following the fault codes, I found the disconnection of some sensors, such as a water temperature sensor, TPS, vacuum sensor and intake air temperature sensor. 

4.             Repair fault

4.1         Plug back in the connector, or repair problem found

Describe what you did:

 After plug back.in the connector, I have checked the engine condition and retested the signal voltage of sensors. The engine have recovered with appropriate conditions.

5             Clear Codes 

Describe what you did to clear the codes:

 I made a disconnection of negative terminal of a battery or main fuse for 30 seconds.

6             Recheck for codes and record codes in system now:

 After clear codes, E1 and TE1 of diagnosis box should be reconnected. When the ignition switch is turned on and the engine is not running, the check engine light is contantly flashing that means normal condition of the engine without any faults.

7             How could the faults found affect the engine performance?

           

 From the faults, the engine does not run properly and has abnormal conditions with lower engine performance.

8             Discuss what other tests you should be doing once you have found the fault codes:

 I can recheck the voltages of sensor's signal using a multimeter and lab scope with manufacturer specification. In addition, I can find out the fault codes easily from using scan tool diagnostics.  

WS4 Fuel Pressure and flow

WS4 Fuel Pressure and flow (Petrol only)


Warning, be careful around raw fuel. It can catch fire! Use appropriate safety precautions. Keep sparks, flame, your body and your clothing away from raw fuel! Know where your fire extinguishers are and use them if necessary.


1. Locate the two closest fire extinguishers. (If you have to use it remember to pull the pin, squeeze the handle, and spray at the base of the flame.) Write down where they are:
               Fire extinguishers are located by the main door.


2. If you can, look up Fuel Pressure specifications for the vehicle you are testing. If you can’t look them up, make a guess at the fuel specs you should have and write them down here:
              265 ~ 304 kPa (2.7 ~ 3.1 kgf/㎠, 38 ~ 44 psi) 
3. Use eye protection. Optional: Relieve fuel pressure before installing pressure gauge. Or there will be some fuel that sprays at you as you attach the gauge. You can relieve pressure by several methods: 1) To relieve the fuel pressure. Make sure you have a rag to catch the fuel, start the engine. 2) Remove fuel pump (circuit opening) relay or fuse and run the engine until it stops, then crank to check that the engine doesn’t start 3) Use a vacuum gauge on the pressure regulator to lower fuel pressure, or 4) Open a fuel line at some pressure point and catch the fuel in a rag beware there may be lots of fuel.

4. Attach fuel pressure gauge and notice which scale on the gauge you will be using. Briefly turn key on or start vehicle, then turn it off. Check for fuel leaks.
Are there leaks? Yes ..................... No .....√.......
If there are leaks you must correct them and retest before continuing. If you need help, ask ! 

5. Measure the fuel pressure with the key on, engine off.
Record it here: 300 kPa (also record the units you are using, psi, bar,
Kpa, etc…) 43 psi 

6. Idling: Measure the fuel pressure with the engine idling. Watch the pressure for a couple of minutes.
Record pressure here: 280 kPa

7. Maximum: With the engine idling, use the special tool to clamp the fuel return line. Note: this can only be done for a short period.                                                      
Record pressure here: 600 kPa      

8. WOT: With the engine idling, disconnect and plug the vacuum line going to the fuel pressure regulator.
Record pressure here: 340 kPa        
9. Residual: Turn off the engine, and watch the fuel pressure for five minutes.
Record your residual or rest pressure here: 300 kPa      
10. Flow: Hook up proper equipment to read fuel volume if necessary. Record flow gauge results of volume, or how much pumped in 15 seconds: (normal results may be ½ liter in 15 seconds) 
                                      Around 900 ml 

11. Replace vacuum lines. Carefully remove the fuel pressure gauge (beware of fuel spraying into eyes, avoid sparks, etc.) Turn engine key on and off, check for leaks. Start engine, check for leaks. No leaks? Check here:
Replace cap over fuel pressure test port. Check when done: OK 
Make sure the vehicle is safe and runs fine when done, or tell your instructor.

12. Explain why it is important to know a vehicle fuel pressure/flow?
 The injector operates correctly under the correct fuel pressure.

13. Describe the symptoms a vehicle would give with each case

Low fuel pressure
 The engine idling drops and the engine runs roughly. The engine performance reduces significantly. 
Low fuel flow
 Low fuel flow is occured by blocked fuel filter and weak reaturn valv and fuel pump. This produces low fuel pressure  and rough idling as well due to insufficent fuel suppling for injectors.

High fuel pressure High fuel pressure is produced by the fault of the return fuel regulator. More fuel goes through the injectors with dripping fuel to the injectors. 

Faulty fuel pressure regulator
 Flouding of injectors with high fuel pressure which will leak out the injectors. This causes hard starting, poor econmic and the high consumptin of fuel. 

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.

Diagnosis for Toyota 1ZZ engine

We can find out the fail of sensors form the engine diagnosis of the lab scope.


1. A black lead of a lab scope is touched the earth and a red lead is connected the sensor signals. And then, I watch the voltage, Hz and duty cycle from the sensors and outputs and I record the values.


Chart of Inputs and Outputs for Toyota 1ZZ

Measure the signals with a multimeter, set to the right setting, and record in the boxes.
  

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Coolant Temperature (THW or ECT) DC volts	Cold engine 3.639 v	Warmed-up engine 1.07 v
Throttle Position Sensor DC volts	Closed throttle 0.611 v	Open throttle 3.881 v
Crank or RPM sensor AC volts and Hertz	Idle rpm 0.03 v, 477.6 Hz	2500 rpm 0.05 v, 1.332 kHz
MAP sensor DC volts	Idle vacuum 0.547 v	No vacuum or key on engine off 1.801 v
Air Temperature (THA or IAT) DC volts	Cold engine 3.621 v	Warmed-up engine 3.07 v
O2 sensor DC volts	Idle 0.005 v	2500 rpm 0.847 v
CAM sensor AC volts & Hertz	Idle rpm 0.15 v, 22.14 Hz	2500 rpm 0.26 v, 58.42 Hz
Fuel Injector Duty cycle %	Idle 1.3%	Acceleration 6.8%
Idle Air Control Duty cycle %	Idle 41.4%	Cranking or 2500 41.4%

2. Diagnosis
A lecturer create a fault under this Toyota diagnosis. I found eight faults in this test.

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	Faulty sensor or output	Lab Scope	Engine Condition described
1	Injector #4	Wrong duty cycle in #4 cyl	The engine run roughly with vibration.
2	TPS	No voltage. When the throttle was closed and opened, the voltage does not go up and down.	The engine still run but the engine does not run appropriately, when I open the throttle. The sensor voltage dose tell the ECU wrong values for the fuel injection.
3	MAP Sensor	The voltage does not move	The engine does not run appropriately from the wrong signal of the vacuum sensor.
4	Crank Position Sensor	No frequency, AC voltage	The engine stopped completely. No fuel injection and ignition.
5	Cam Position Sensor	No frequency, AC voltage	The engine stopped completely. No fuel injection and ignition.
6	O2 Sensor	No voltage values in the idling and acceleration	The engine does not run appropriately from the wrong signal of O2 sensor.
7	Injector #4	Wrong duty cycle in #4 cyl	The engine run roughly with vibration.
8	Cam Position Sensor and injector #4	No frequency, AC voltage and no supplied voltage of injector #4	The engine stopped completely. No fuel injection and ignition. In addition, there were two problems in this engine.