WS8 Primary & Secondary Ignition Patterns

Q. Are all the primary ignition voltage reading reading normal?
A. Yes

Discuss the normal and abnormal about this pattern and what causes it?
The above pattern is the normal pattern for this primary circuit because it has dwell time, firing time, burn voltage and burn time. Abnormal pattern may miss one or more above configrations.

Show the detail you need to see for diagnosis.
To diagnose the above graph, we need dwell time, burning voltage, firing voltage and burn time on the graph
Discuss what the primary display or parade pattern emphasizes for diagnosis. what can it help you see?
Primary display tells us how this primary circuit play a role in spark generation in spark plug through secondary wiring. It help us to see the exact voltage pattern on ignition oscilloscope and to find the fault in it if any which is effecting the engine performance.
2. Secondary Voltage Patterns

Set up your ignition oscilloscope or lab scope to vies the secondary ignition patterns on your lab scope, with the engine warmed up and idling. (use parade mode or individual mode on each different cylinder, depending on scope available)

Record the average firing voltage for each cylinder in the chart below. Some variation is normal, just pick the average.

Record the Average Burn Time for each cylinder in the chart below

Q. Are all these secondary ignition voltage reading normal?
A. Yes

Discuss what is happening in the pattern and what it telling you about the ignition system
It shows us that to create a good spark across the air gap in the plug, we need very high voltage in  very shot time.

Draw or photograph the shorted secondary ignition waveform you see now on your scope.

Discuss what is happening in the shorted ignition pattern and how the ignition pattern tell you what it is happening in the ignition system.
In this pattern, the firing voltage is very high for No. 4 plug  and burn time is very low but all other three plug having low firing voltage and high burn time.
Remove the ground wire and attach the spark plug wire back on the engine so it is normal again. Run the engine a bit to clear the spark plug.

Draw  or photograph the spark tester Secondary ignition waveform you see now on your scope. show the detail that is necessary for accurate diagnosis. Include time and voltages.



Discuss what happens to the ignition waveform when the spark tester is attached to the spark plug wire. What does it tell you about the ignition system?

Remove the spark tester carefully and put everything back together on the engine.

Engine run fine?

Yes.

WS7 Exhaust gas Analysis (Petrol only)

2. Start the engine Idling cold and record the four gas readings. Explain what is happening within the engine referring to the four gases:

Co: 0.506      HC: 188     CO2: 14.08    O2: 1.4

Low oxygen means the engine is running rich. As engine running rich, high HC coming out in exhaust gas. High CO2 is also caused by rich condition but high CO telling us that there is not much O2 in the exhaust to convert it into CO2 and also the catalytic converter is cold yet to convert it into CO2.

3. When the engine has warmed up, record the four gas readings. Explain what is happening within the engine referring to the four gases:

CO:  0.476     HC:  221     CO2: 14.35     O2:  0.84

The engine is running more rich in this scenario. High HC, CO2 and low O2 are the signs of  rich condition of the engine. High CO may be because of low O2 availablity to converter it into CO2 or may because of cold catalytic converter.

4. Run the warm engine at 2500 RPM, record the four gas readings: Explain what is happening within the engine referring to the four gases:

CO: 0.713    HC: 249    CO2 14.06     O2: 1.09

O2 is now seems increasing. It means the engine is going toward rich side. CO2 is  not changing much. HC is going high because of high RMP and more fuel is coming into the cylinders. CO is increasing because of high RPM and also may not converting into CO2 because of cold catalytic converter.

5. At Idle, create a lean condition with an air leak or vacuum leak, record the four gas readings:

Explain what is happening within the engine referring to the four gases:

CO: 0.08     HC: 3745     CO2: 3.65     O2: 16.10

High O2 in exhaust gas shows the engine is running lean but on other hand high HC means its running rich. But here high HC does not mean that its running rich because low CO and CO2 values with high HC means the fuel is not burning proper in this scenario because of vaccum leak

6. Accelerate the engine, by blipping the throttle a few times (don't rev too high and damage the engine) and watch how the gas readings change. Record the four gas readings when CO is highest. Explain what happening within the engine referring to the four gases:

CO: 3.638    HC: 304    CO2:  11.29     O2:  2.83

High CO, HC and Low CO2 means the fuel is not buring properly because of lack of sufficent O2 for proper burnung because blipping of throttle sucking less air as compare to fuel going into the cylinders.

7. Disconnect one spark plug wire, ground it with a jumper wire, then record the four gas readings as the emgine Idles. Explain what is happening within the engine referring to the four gases:

CO: 0.07    HC: 104     CO2: 12.3     O2: 4.43

High HC and O2 in exhaust gas may be because of unburnt fuel in one cylinder . Low CO and high CO2 are because of catalytic converstion of converter.

8. If you can get it, disconnet the injector harness connector from one injector on an engine that has one injector for every cylinder. Record the four gas readings as the engine Idles.

Explain what is happening within the engine referring to the four gases

CO: 0.09    HC: 92     CO2: 12.26    O2: 0.14

There is not much changes in the gas values as it is the same thing to disconnet the spark plug and take the harness out from one of the injector because there will not fuel burning in one of the cylinder in both cases.

9. Optional: Make other changes to the cylinder at idle, such as turning on the air conditioning or rocking the steering wheel. Note the change you made: turning the AC on and rocking steering wheel both.

Explain what is happening withing the engine referring to the four gases:

CO: 1.069    HC: 160     CO2: 14.7    O2: 0.14

With AC on and rocking steering wheel, more power is needed to do so. To compensate this need, engine will work hard and need more fuel and because the engine is at Idle so not more air can enter through the throttle. Thats' why even HC is burning properly but because of low air, some coming out as unburnt. High CO2 because of high combustion and more CO in exhaust because of low O2 to convert it into CO2 by the catalytic converter.

10. Explain the different readings you would get from a vehicle with a catalytic converter and a vehicle without one and why?

With vehicle having catalytic converter, the CO and O2 values would be low and CO2 value would be high but the vehicle without it would have CO and O2 values high in the exhaust gas and CO2 would be low.

11. Explain what the light off point means and what happened?

12.  On lambda, O2 sensors why do they have 1,2,3,4 or 5 wires and what do these extra wires do?

 Two wires are the battery positive and negative wires and third wire is a sensor wire which bring the signal from sensor to ECU and forth wire is ground wire for the sensor.

    

WS6 Oxygen Sensor on vehicle

How high the voltage go? about 0.8 V

How low does the voltage go? about 0.2 V

Average Voltage: 0.5 V

How many cross counts? 12

Q. If the signal is not cycling normally, describe what the signal does?
A. Cycling normally

Q. How high does the Oxygen sensor voltage go?

A. About 1.15 V

Q. If this signal is not going high normally, describe what the signal does?

A. It went high at once at the time of high acceleration of the engine and the but that when we let it free, the signal stayed average about 0.7 V for two seconds.

Q. How high does the Oxygen sensor voltage go?
A. About 1.0 V

Q. If this signal is not going high normally, describe what the signal does?
A. It was normal when the engine was Idle. Once we accelerate the engine, the voltage dramatically dropped down close to zero volt or we can say close to 0.1 V and stayed there for few second, about two seconds, before jumping up to.

Q. How long the sensor took to go from lean to rich?
A. About 0.1s

Discuss how a normal Zirconium Oxygen sensor works: draw a picture below to help show how it works?

Q. Discuss how good or bad this Oxygen sensor is. what about it functions well or is faulty? Use detail and specific voltage in your discussion. Can it accutely tell the ECU how rich or lean the exhaust is?
A. This is a good oxygen sensor. Oxygen sensor works well. It shows normal signal on oscilloscope . The voltage goes from about 0.15 V to 0.95 V in a cycle.
Yes it accurately  tells the ECU about the rich and lean condition of exhaust gas.

WS5 Scan Tool Diagnostics

 









WS4 Fuel Pressure and Flow ( Petrol only)

6. Idling: Measure the fuel pressure with the engine idling: 250 Kpa

7. Maximum: With the engine idling, use the special tool to clamp the fuel return line.
    Pressure: 450 Kpa.

8. WOT: With the engine idling, disconnect and plug the vacuum line going to the fuel pressure regulator.
    Pressure: 325 Kpa

9. Residual: Turn off the engine and watch the fuel pressure for five minutes.
    Residual pressure: 275 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 half litter in 15 seconds)
2.2 L/m = 2.2/4 per 15seconds = 0.55 per 15 seconds.

12. Explain why it is important to know a vehicle fuel pressure/flow?
It is important to know about the vehicle fuel pressure because low or high pressure may effect the engine performance. High pressure push more fuel in the injectors and makes the engine run rich and low pressure makes it run lean.
13. Describe the symptoms a vehicle would give with each case:

Low fuel pressure: The engine will run lean and the oxygen sensor will give send the signal to ECU to reduce the amount of air so makes the throttle more close  even there is high demand of air for engine performance

Low fuel flow: Low fuel reduce the pressure in the hose so the above situation is created there.
High fuel pressure: High pressure put more fuel in the injector so makes engine run rich and so oxygen sensor will sense that there is shortage of air and will send the signal to ECU to send more air in and hence effect engine performance

Faulty fuel pressure regulator: It may send the fuel at high pressure or at low pressure

WS3A General Lab Scope

Explain the operation of the sensor or device using the graph:

(Use arrows at different points, and describe what happens there)

At "A" it shows that engine is running rich and at "B", it shows that the engine is running lean. "C" indicates that ECU adjusted the fuel consumption in that way so that it runs engine rich longer to keep efficient engine performance. In this case engine is running in close loop.

Explain in detail an electrical fault that would make this unit operate incorrectly:

The fault in TPS. IAT MAP and MAF sensors make this unit operate incorrectly

Explain why this condition would cause this unit to malfunction/use mathematical equations to back up your explanation:

These sensors will send wrong signal to the ECU in form of voltage. Some sensors have resistance in them, which changes with temperature and others changes voltage with pressure caused by air flow, thats further change the resistance of the sensors.  

Using the graph draw the patteren that this unit would give with this fault (include the different points as with the previous pattern)

Q.Expalin how this condition would affect the operation of the vehicle?

A.The vehicle may run rich or lean



Use arrows at different points and describe what happens there
At "A" there is a constant voltage in the primary winding and it means the magnetic field is building up. At "B" the circuit is broke up and the there is not voltage during this time period but

Explain in detail an electrical fault that would make this unit operate incorrectly
inadequate power supply, high resistance in primary wiring and secondary wiring and air gap in plug electrodes
Explain why this condition would cause this unit to malfunction/use mathematical equations to back up your explanations.
Because of  high resistance in primary and secondary wiring wouldn't generate enough spark to ignite the air fuel mixture and air gap would also cause inaccurate spark.

Using the graph, draw the pattern that this unit would give with this fault (include the different points as with the previous pattern)


Explain how this condition would affect the operation of the vehicle?
Not proper combustion in the cylinders. The engine will give the piking sound, low engine performance, high emissions.

(use arrrows at different points and describe what happens there)
It is switch type of TPS and after around every one second it closed down and in next second it opens again. At "A" it is opened and at "B'' it is closed.

Explain in detail an electrical fault that would make this unit operate incorrectly
Even it will open and close with help of air pressure but if there is and electric fault in it, It will send the wrong signal to ECU. ECU will process and send the wrong signal toward actuators, which will effect the engine performance.
Explain why this condition would cause this unit to malfunction/use mathematical equation to back up your explanation
It will send the wrong signal in form of voltage and the voltage changes in it by movement of the throttle.

Using the graph, draw the pattern that this unit would give with this fault (include the different points as with the previous pattern)

Explain how this condition would affect the operation of the vehicle?
The engine will either run rich or lean depending upon in the voltage that ECU receive.

(use arrows at different points and describe what happens there)
At "A" the maximum air going through MAF and at "B" the minimum amount of air going through the sensor. At "C" and "D" when there the very low amount of air going through the MAF before next flux of air going through it.

Explain in detail an electrical fault that would make this unit operate incorrectly
Incorrectly operation of MAF will send the wrong signal about how much air is going in through it and thus ECU will process it incorrectly that how much air is needed to run the engine efficiently.
Explain why this condition would cause this unit to malfunction/use mathematical equation to back up your explanation:
The signal is sent to ECU in voltage form and MAF changes it voltage according to how much air is going through it.
Using the graph, draw the pattern that this unit would give this fault (include the different points as with the previous pattern)

Explain how this condition would affect the operation of the vehicle?
The engine will run out of order in terms of rich and lean condition

Explain the operation of the sensor or device using the graph;
(use arrows at different points and decribe what happens there)
There is a crankhaft sensor over the fly wheel. It has number of teeths on fly wheel and a hole for TDC. When the pully rotates, the sensor senses the lots of teeth and groves in it. It then send the voltage changes by this to ECU

Explain the operation of the sensor or device using the graph:
IAT sensor is a NTC. At high temperature the resistance is low and hence increased voltage. In above graph the temperature of coolant increasing which makes the sensor resistance lower and cause increased voltage at its terminals.

Explain the operation of the sensor or device using the graph:
(use arrows at different point and describe what happens there):
MAP sensor here is changing its voltage as the pressure or vacuum in changes in the manifold. Voltage is high when there is more vacumm in the manifold and low when  there is low vacuum in it.

Explain the operation of the sensor or device using the graph:
The above graph shows that the engine is running in close loop. It means that engine is warmed up. The point in graph where it touched the highest voltage shows that the engine is condition is rich and lowest point shows that it is lean.