Exhaust Gas Analysis
Exhaust gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack or propelling nozzle.
Exhaust gas is emitted as a result of the combustion of fuels such as natural gas, gasoline/petrol, diesel fuel, fuel oil or coal. According to the type of engine, it is discharged into the atmosphere through an exhaust pipe, flue gas stack or propelling nozzle.
Exhaust Analyser should be warmed up and recently calibrated. When it’s time to start taking tailpipe readings, put the analyser probe into the tailpipe and install exhaust tube over probe to capture exhaust fumes. Make sure there is adequate ventilation.
Note: make sure you fill out the “means: ............. segment to explain what that gas reading means. Example, if you are measuring HC, which shows us about misfire in the engine, and you had a low number like 28 ppm, you would say “shows low amount of misfire”, or “most of the fuel is being burnt.” But if the HC was high, like 340 ppm, you might say “There is a high amount of misfire” or “not all the fuel is being burnt.”
Readings are from a Ford KA & Toyota Corrolla FXGT AE82 with a 20valve silver top
1. With the analyser probe sensing normal air, what are the Four Gas readings? Record the amount and then what it means:
CO 0.00 means: There is no CO in the atmoshpere HC 13ppm means: Higher HC means that unburn fuel remains in the exhaust gases.CO2 0.00%means: EfficencyO2 20.91 means: It is lean
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 4.46% HC 1839 CO2 9.88 O2 9.26
Co is high becuase O2 is low , as the engine starts cold the CO increase to 4.46%. Hc is also high which means that rich mixture enters the combustion chamber. The CO2 (efficency) is low because there isnt enough o2 and the O2 is high from the inactive catalytic converter , cause by the unburnt gaeses
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 0.162 HC 79 CO2 4.02 O2 1.10
Now that the engine is warmed up, the CO & HC decrease. This means that the ideal mixture enters the combustion chamber and the cat convertor is working therefore the engine is running efficently. The CO2 is high and the O2 is low because the most of the fuel is being burnt.
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 2.5 HC 173 CO2 12.71% O2 1.63
Co is low and more o2 as the engine is running warm at 2500 rpm, the CO and HC Increase due to higher RPM with more emissions. CO2 is good and O2 is low becuase of the gaes being burnt
5. At idle, run the mixture rich with extra propane, LPG, or carburettor cleaner, and record the Four Gas readings:
5. At idle, run the mixture rich with extra propane, LPG, or carburettor cleaner, and record the Four Gas readings:
Explain what is happening within the engine referring to the four gases:
CO 1.8 HC 224pmm CO2 225 O2 0.79
Engine is running rich because we had disconnected the vacuum hose in the fuel regulator , Hc is higher which makes it less efficient. The CO also increases to 1.8 which means that is is a rich mixture.
6. 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 0.175 HC 959 CO2 7.75 O2 9.65
When the engine was at idle we disconnected the PCV valve to make it run lean. The CO is nomal ,the unburnt fuel goes up and CO2 is reduced but the O2 increases significantly which means that is has a lean mixture.
7. Accelerate the engine, by blipping the throttle a few times (don’t rev too high anddamage the engine), and watch how the gas readings change. Record the Four Gas readings when the CO is highest:
Explain what is happening within the engine referring to the four gases:
CO 3.547 HC 699 CO2 12.39 O2 0.58
We suddenly accelerate and let go, there is a rich mixture going into the combustion chamber and HC rise. The CO is reduced as there is less O2 .
8. Disconnect one spark plug wire, ground it with a jumper wire, then record the Four Gas readings as the engine idles:
We suddenly accelerate and let go, there is a rich mixture going into the combustion chamber and HC rise. The CO is reduced as there is less O2 .
8. Disconnect one spark plug wire, ground it with a jumper wire, then record the Four Gas readings as the engine idles:
Explain what is happening within the engine referring to the four gases:
CO 0.582 HC 1291 CO2 12.04 O2 7.61
Co is high because there is low 02 as the misfire is produced in a cylinder, the HC increases because the unburnt fuel is created by the misfired cylinder. The O2 is also produced more from the air/fuel mixture of the misfired cylinder.
9. If you can get to it, disconnect 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 0.247 HC 217 CO2 11.68 O2 5.17
The injector is disconnected, Co is low because air is going through the cylinder and the HC is low because less air going through Alos Co2 is low due to effiecient combustion and O2 increases because one cyclinder is not burning.
10. Optional: Make other changes to the engine at idle, such as turning on the air conditioning or rocking the steering wheel. Note the change you made:
Explain what is happening within the engine referring to the four gases:
CO 0.300 HC 74 CO2 14.73 O2 0.12
Overall the readings were all good, the emission is clean with proper values. However, when loads (air conditioning and rocking the steering wheel) are added, the rpm will go up. As a result , the CO and HC increase slightly with the rich condition.
Overall the readings were all good, the emission is clean with proper values. However, when loads (air conditioning and rocking the steering wheel) are added, the rpm will go up. As a result , the CO and HC increase slightly with the rich condition.
Return the vehicle to good condition and proper adjustment.
11. Explain the different readings you would get from a vehicle with a catalytic converter and a vehicle without one and why?
You would get the differnt readings, without the catalytic converter there will be more Co and HC as the catalytic converter creates a chemical reaction to change the emission into something else which is less harmful to the atmosphere.The catalytic converter helps reducing emissions with its chemical actions.
12. Explain what light off point means and what happens?
For the catalytic convertor to work the temperature should be hot to work, the catalytic converter will clean the emissions by reducing toxic gases in the exhaust system with its operating temperature.
13. On lambda, 02 sensors why do they have 1,2,3,4 or 5 wires and what do these extra wires do?
13. On lambda, 02 sensors why do they have 1,2,3,4 or 5 wires and what do these extra wires do?
One is heater positive and there is a negative, the O2 sensor works correctly and increases responses with operating temperature when the engine starts cold.The black wire is a snesor signal positive which gives the state of exhaust gases to the ECU. The gray wire is a sensor signal earth![]()
Oxygen Sensor
4.1 Freeze your pattern and draw or photograph it onto the graph below: Note the voltage and time per division or scale next to the graph.
5.1 Freeze your pattern as it goes rich and draw or photograph it onto the graph below: Note the voltage and time per division or scale next to the graph.
5.2 How high does the Oxygen sensor voltage go? 0.9 V
7.0 Measure the Response Time of the sensor. freeze the pattern and measure how long it took the sensor to go from lean to reach.
7.1 freeze your pattern as it goes suddenly rich from a lean condition and draw it into the graph below . Normally you want the voltage to go from below 0.2 V to above 0.8V. In less than 100 ms .
7.2 Measure how long the sensor took to go from lean to rich. Use the sensors coursers on the scope if necessary. Record how long the sensor took here: 1.50 ms
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Too much fuel being used running rich , dripping injectors means that there will be flooding , return regulator will be broken.
Fill in the letters used to label the information and the value of that data. (For example, engine load information may be found under MAP, with a value of
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When we do a snap acceleration, the firing voltage slightly increased. This means that the higher rpm needs a higher firing voltage with short amount of burn time
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So it is normal again. Run the engine a bit to clear the spark plug
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Dual trace
Using a dual trace (two channels A/B) oscilloscope capture the following
Lab Scope Referance:
Oxygen Sensor
An oxygen sensor,is an electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analyzed.
1.1 Locate an oxygen sensor on your vehicle. Describe where it is located:
1.1 Locate an oxygen sensor on your vehicle. Describe where it is located:
It is located in the exhaust manifold or in the exhaust downpipe before the catalytic converter.
1.2 How many wires for this oxygen sensor? 4
1.3 Record the colours for each of the wires at the sensor side of the connector (not the ECU side of the connector). Then list the use of the wires. Usually a black or blue wire will be the O2 sensor signal, Grey may be the sensor ground. Heater power and ground are often white. But there may be other colours. You may have to consult a wiring diagram.
Colour Use or Purpose
White Heater Positive (+)
White Heater Negative (-)
Grey Signal Negative (-)
Black Signal Positve (+)
White Heater Negative (-)
Grey Signal Negative (-)
Black Signal Positve (+)
1.4 What type of Oxygen Sensor is this? (tick one)
Zirconia switching sensor? ✓
Titania switching sensor? …….
Titania switching sensor? …….
Broadband Air Fuel Ratio sensor? (one cell) …….
Broadband Air Fuel Ratio sensor? (two cell) …….
2.0 Now we Back probe the Oxygen Signal Wire with a pin and connect to an oscilloscope. If you need help using the oscilloscope see your lecturer or other help sources. Check that you are connected to the Oxygen sensor signal: Run the engine and check that you are seeing a signal. Connected OK? Yes ✓
3.0 Watch and Record Oxygen Signal pattern at 2500 rpm. Let the engine warm up and enter closed loop so you see a normal cycling pattern. You may have to hold the rpm about 2500 for half a minute to go into closed loop.
3.1 Freeze your pattern and draw or photograph it onto the graph below: Note the voltage and time per division or scale next to the graph.
3.2 How high does the voltage go? 0.8v
3.3 How low does the voltage go? 0.2v
3.4 What is the average voltage? 0.4v
3.4 What is the average voltage? 0.4v
3.5 How many “Cross Counts” does the signal have in 10 seconds? (One cross count is when it goes from high to low, or from low to high.) List here: 30
3.6 If the signal is not cycling normally, describe what the signal does:
If it Misfires in one cyclinder , the cycle will have dips in it.
4.0 Watch and Record Oxygen Signal pattern at Idle rpm. Let the engine warm up and enter closed loop so you see a normal cycling pattern. You may have to hold the rpm about 2500 for half a minute to go into closed loop. Then let the RPM come down to idle.
4.1 Freeze your pattern and draw or photograph it onto the graph below: Note the voltage and time per division or scale next to the graph.
4.2 How high does the voltage go? 0.8v
4.3 How low does the voltage go? 0v
4.4 What is the average voltage? (Some oscilloscopes have functions that will calculate the average for you. If not, just guess.) 0.4v
4.5 How many “Cross Counts” does the signal have in 10 seconds? (One cross count is when it goes from high to low, or from low to high.) List here: 7
4.6 If the signal is not cycling normally, describe what the signal does:
It may have a negative pattern on the graph .
5.0 Make this Oxygen Sensor go rich by accelerating once or twice. (The fuel system should normally make the system go rich when you do a sudden acceleration.) Push on the accelerator quickly but don’t let the rpm go high enough to hurt the engine. (If you act like you will hurt the engine you will be asked to leave lab.) The signal should go over 0.85V.
5.2 How high does the Oxygen sensor voltage go? 0.9 V
5.3 If this signal is not going high normally, describe what the signal does:
It will have a very low voltage and it will be lower than 1.0 volt.
6.0 Make this Oxygen Sensor go lean by doing sudden deceleraton. Gently run the rpm to about 3000 , and let the rpm drop suddenly. The fuel system should make the system go lean on deceleration. The signal should go below 0.2 V
6.1 Freeze your pattern as it goes rich .
6.1 How low does the oxygen sensor voltage go? 0.2 V
6.2 If this signal is not going low normally , describe what the signal does:
The signal will be above zero volts , might be a slugish oxygen sensor
6.1 Freeze your pattern as it goes rich .
6.1 How low does the oxygen sensor voltage go? 0.2 V
6.2 If this signal is not going low normally , describe what the signal does:
The signal will be above zero volts , might be a slugish oxygen sensor
7.0 Measure the Response Time of the sensor. freeze the pattern and measure how long it took the sensor to go from lean to reach.
7.2 Measure how long the sensor took to go from lean to rich. Use the sensors coursers on the scope if necessary. Record how long the sensor took here: 1.50 ms
8.0 Discusses how a normal Zirconium oxygen sensor works: draw a picture below to help show how it works?Zirconium oxygen sensor has two electrodes which provide an output voltage corresponding to the quality of oxygen in the exhaust in relation to the atmosphere. The output of 0.2 V represent a lean mixture. The Zirconia oxygen sensor technology operates though a known voltage being generated through oxygen interaction with the ziconium when it is heated to over 700ºC.
9.0 Discuss how good or bad this oxygen sensor is. What about it function well or is faulty? Use detail and specific voltage in your discussion. Can it accuratelly tell the ECU how rich or lean the exhaust is?
This sensor elements the rich/ lean cycling allowing the control unit to adjust the fuel delivery and ignition timing of the engine much more rapidly, but less sensitive to either rich or lean. 0.2 volts represent lean and 1 volt represent rich mixture.
This sensor elements the rich/ lean cycling allowing the control unit to adjust the fuel delivery and ignition timing of the engine much more rapidly, but less sensitive to either rich or lean. 0.2 volts represent lean and 1 volt represent rich mixture.
Fuel Pressure and flow
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:
Front left of the room by the 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:
34-44psi
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 there are leaks you must correct them and retest before continuing.
5. Measure the fuel pressure with the key on, engine off.
Record it here: 35psi
6. Idling: Measure the fuel pressure with the engine idling. Watch the pressure for a couple of minutes.
Record pressure here: 38psi
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: 80psi
8. WOT: With the engine idling, disconnect and plug the vacuum line going to the fuel pressure regulator.
Record pressure here: 48psi
9. Residual: Turn off the engine, and watch the fuel pressure for five minutes.
Record your residual or rest pressure here: 42.5psi
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)
666ml
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: ✓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?
To make sure it is running at its maximum capacity , and it is important to keep the fuel being injected into the engine at the correct amount
13. Describe the symptoms a vehicle would give with each case
Low fuel pressure
It will run lean , it wont idle properly. RPM will be low and it will be running rough and have low performance
Low fuel flow
Blocked fuel filter , weak return vavle in pump , sping cam gets weaker it will always be richer , which means it will use alot of fuel
High fuel pressure
Too much fuel being used running rich , dripping injectors means that there will be flooding , return regulator will be broken.
Faulty fuel pressure regulator
Floading of injectors which will leak out. The injectors causes hard starting , poor economy and useing more fuel which makes it run rich
After i had did the fault check , i had to check the voltages to see if it was within the speciification on all the sensors to check if they were any faults and all the sensors function correctly
Scan Tool DiagnosticsFlash codes
We did a test on a Mitshubishi Legnum 1997
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
To find a fault code on the engine you will see the engine light flashing.We earth out on the data link connector then turn the key on without starting the vechile. The codes will begin to flash on the check light.
All codes are 2 digit numbers. The codes 55 indicate the end of the message.
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 |
23 | Cam Sensor | Engine wont start |
41 | TPS | No voltages |
31 | Intake Air temp | Rough idle , struggle on acceleration |
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:
I found out that there were disconnected of some sensors, such as a Cam sensor, TPS, intake air temperature sensor.
Check the condition of the wires
4 Repair fault
4.1 Plug back in the connector, or repair problem found
Describe what you did:
After i pluged back in the connector, I have checked the engine condition and retested the signal voltage of sensors. The engine have recovered with appropriate conditions.
I checked the code numbers again , then i dissconnected the battery terminals for 30 seconds and put it back on the battery and tunred the engine to check the light was flashing that means that the codes are now cleared
I checked the code numbers again , then i dissconnected the battery terminals for 30 seconds and put it back on the battery and tunred the engine to check the light was flashing that means that the codes are now cleared
5 Clear Codes
Describe what you did to clear the codes:
It was very simple , i just disconnected the neagative lead on the battery and then took the main fuse our for about 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. I rechecked the codes and found there was no codes which mean they were all cleared
7 How could the faults found affect the engine performance?
The engine wouldnt run properly which mean low engine performance and it could also create idling problems and will misfire
8 Discuss what other tests you should be doing once you have found the fault codes:
After i had did the fault check , i had to check the voltages to see if it was within the speciification on all the sensors to check if they were any faults and all the sensors function correctly
Make Mitshubishi Model Legnum .Year 1997
1. Scan Tool Data
1.1 Find a vehicle which is appropriate for the scan tool.
1.2 Connect the scanner, power it on, follow the instructions and input the correct vehicle information it asks for so you can view the data.
1.3 Find the data for the information listed on the next page.
Turn engine on to
3.6, listed in volts) Note: not all vehicles will support all information, just find as much as you can. If the engine won’t
run, input the information with the key on, engine off.
Type of information (PID = Parameter Identification) | Letters to describe it E.g. TPS | Value of data | Units for data E.g. volts |
Engine Load (how much air comes in) | MAF | 1.3 | V |
Engine RPM | Crank | .068 | RPM |
Throttle angle | TPS | 624 | Mv |
Engine coolant temperature | ECT | 71 | °C |
Intake air temperature | IAT | 27 | °C |
Fuel Injection opening pulse | Injection | 0.5 | Ms |
Transmission select position | Manual | Neutral | N |
Vehicle Speed | Km/H | 0 | KM |
Oxygen sensor(s) | O2 | 351 | MV |
Fuel Trim | - | - | - |
Idle control | ISC | 42 | STEP |
Power steering condition | - | On | - |
Air conditioning condition | AC signal | OFF | ON/OFF |
Exhaust Gas Recirculation (EGR) | - | - | - |
Fuel Evap or Purge condition | - | - | - |
Malfunction Indicator Light (MIL) | Check Engine Light | OFF | ON/OFF |
Barometric Pressure | Pressure Sensor | 99 | KPA |
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 |
23 | Camshaft Sensor | Low Voltage |
3 Lecturer put in Fault
3.1 Find your lecturer and have him create a fault under the hood (don’t look)
4 Record New Codes
4.1 Look up the codes now in the scan tool
4.2 Record the codes in the chart below. Also record what system is affected, and what condition is described.
Code number | System affected | Condition described |
31 | Vaccum Sensor | High Voltage, Causes engine to stall |
22 | Coolant Temp | High Voltage |
5 Find What Data Has Changed
5.1 Look through the scan tool data to see what PIDs (Parameter Identification of system voltages) have changed. Which readings don’t make sense or don’t read what you would expect. Concentrate on the PIDs related to the codes.
5.2 Record the PIDs that have changed below:
Type of information (PID = Parameter Identification) | Letters to describe it | Value of data | Units for data |
Intake Manifold | 46 | KPA | |
Coolant Temp | ECT | 0 | °C |
Engine Speed | RPM | 825 | RPM |
6 Visual Inspection to find fault
6.1 Do a visual inspection under the hood 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.
Describe problem you found:
MAP & ECT is disconneted.
7 Repair fault
7.1 Plug back in the connector, or repair problem found
7.2 Describe what you did:
Pluged connectors back
8 Recheck Data PIDs
8.1 Recheck the data with the scan tool
8.2 Record the voltages for the PIDs related to the problem, to confirm they are back to normal
Type of information (PID = Parameter Identification) | Letters to describe it | Value of data | Units for data |
Engine Speed | RPM | 825 | RPM |
Intake Manifold pressure | IMP | 27 | KPA |
Engine Coolant temp | ECT | 70 | ℃ |
9 Clear Codes
Describe what you did to clear codes:
I disconnected of the negative terminal off the battery and took out the engine main fuse for 30 seconds
10 Recheck for codes and record codes in system now:
I rechecked the codes by selecting D.T.C, and there was no trouble codes on the screen.
11 Discuss the importance live data when fault finding
It shows the state of the sensors from the live data values
12 Explain the need for parameters when checking live data
So we know the fault is fixed, the live data will be checked with its parameters then the data should be compared to fault datas.
13 Discuss how a scan tool can aid you when fault finding
I can now find the fault easily now even though the vehicle is old or new,or whatever make it is . I can check the state of a vehicle just by plugging in the scan tool and check the data , it is very useful as you can pinpoint the problem.
Primary & Secondary Ignition
Primary & Secondary Ignition
1.0 Primary Voltage Patterns
1.1 Set up a lab scope or ignition oscilloscope to view the primary ignition pattern (in parade or display mode) on your lab scope, with the engine warmed up and idling.
1.2 Record the average Firing Voltage (or “Step Up voltage) for each cylinder in the chart below. Some variation is normal, just pick the average. If you don’t understand what this is, review the resource information available.
1.3 Record the average Burn Voltage for each cylinder in the chart below.
1.4 Record the average Burn Time in milliseconds for each cylinder in the chart below
1.5 Record the average Dwell Time for each of the cylinders in the chart below. What unit of measurement are you using to measure the dwell time?
Milli Seconds 7ms/20%
1.6 Are all these primary ignition voltage readings normal? Yes ✓No ____ Please discuss what is normal or 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
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
Cyl 1 | Cyl 2 | Cyl 3 | Cyl 4 | Cyl 5 | Cyl 6 | Primary Ignition |
300+v | 300+v | 300+v | 300+v | - | - | Firing Voltage |
47v | 50v | 55v | 57v | - | - | Burn Voltage |
1.5ms | 1.5ms | 1.5ms | 1.5ms | - | - | Burn Time |
7ms | 7ms | 7ms | 7ms | - | - | Dwell Time |
1.7 Draw or photograph the Primary Ignition oscilloscope parade pattern from your scope into the box below. Do it carefully and show the detail you need to see for diagnosis. Record voltage and time scales.
1.8 Discuss what the primary display or parade pattern emphasizes for diagnosis. What can it help you see?
The 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
The 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
1.10 Some scopes have the facility to use raster or stacked display. How could this help you to diagnose a fault. What can you see more clearly?
2.0 Secondary Voltage Patterns
2.1 Set up your ignition oscilloscope or lab scope to view 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.)
2.2 Record the average Firing Voltage (or “Step Up voltage) for each cylinder in the chart below. Some variation is normal, just pick the average. If you don’t understand what this is, review the resource information at the back of this worksheet.
2.3 Record the average Burn Time for each cylinder in the chart below.
Are all these secondary ignition voltage readings normal? Yes ✓ No ____ Discuss what is happening in the pattern and what it is 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
2.5 Do a Snap Acceleration (don’t damage the engine by revving too high or for too long) and record in the chart below how high the Firing Voltage (KV) went under Snap Acceleration.
Cyl 1 | Cyl 2 | Cyl 3 | Cyl 4 | Cyl 5 | Cyl 6 | Secondary Ignition |
7KV | 9KV | 6.5KV | 7.5KV | - | - | Firing Voltage (KV) |
3ms | 3ms | 3ms | 3ms | - | - | Burn Time (ms) |
4kv | 5kv | 4kv | 4kv | - | - | Snap Acceleration |
2.6 Are all these Snap Acceleration secondary ignition voltage readings normal? Yes ✓ No ____ Discuss what is happening and what the pattern is telling you.
When we do a snap acceleration, the firing voltage slightly increased. This means that the higher rpm needs a higher firing voltage with short amount of burn time
2.7 Draw or photograph the Secondary Ignition lab scope pattern while idling from your scope into the box below. Do it carefully and show the detail you need to see for diagnosis.
2.8 If you can safely do this, (with the engine stopped), gently disconnect one spark plug wire, and short to the engine with a jumper wire. Which cylinder number did you short? 4
2.9 Start the engine and let it idle (for only a short time.) Record the new Firing Voltage and Burn Time for all the cylinders in the chart below.
Cyl 1 | Cyl 2 | Cyl 3 | Cyl 4 | Cyl 5 | Cyl 6 | Secondary Ignition (one cylinder grounded) |
4.1KV | 4KV | 4.2KV | 2KV | - | - | Firing Voltage (KV) |
- | - | Burn Time (ms) |
2.10 Draw or photograph the shorted Secondary Ignition waveform you see now on your scope.
2.11 Discuss what is happening in the shorted ignition pattern and how the ignition pattern tells 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
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
2.12 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.
So it is normal again. Run the engine a bit to clear the spark plug
2.13 Stop the engine and attach a spark tester to another spark plug wire. Start the engine and let it idle (for only a short time). Record the new Firing Voltage and Burn Time for all the cylinders in the chart below.
Cyl 1 | Cyl 2 | Cyl 3 | Cyl 4 | Cyl 5 | Cyl 6 | Secondary Ignition (Spark tester on one cylinder) |
5kv | 7kv | 7kv | 28 | - | - | Firing Voltage (KV) |
1.6ms | 1.5ms | 1.4ms | 0.3ms | - | - | Burn Time (ms) |
2.14 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.
2.15 Stop the engine, remove the spark tester (be gentle), replace the spark plug wire, and run the engine to clear the spark plug. The engine should be back to normal now.
2.16 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.
The spark tester is at 20 kv (bigger spark gap) in #4 cylinder , the firing voltage increases to 6 kv and the burn time decreases to 1.3ms because there was a bigger spark gap.
As a result, the firing voltage and burn time are related to the spark gap. If the spark gap is small the firing voltage will decrease and the burn time will increase. On the other hand, if spark gap is big the firing voltage will go up and the burn time will drop.
As a result, the firing voltage and burn time are related to the spark gap. If the spark gap is small the firing voltage will decrease and the burn time will increase. On the other hand, if spark gap is big the firing voltage will go up and the burn time will drop.
2.17 Remove the spark tester carefully, and put everything back together on the engine. Engine runs fine? ✓ yes, or ____ no. If any problems with vehicle, please tell your instructor.
Dual trace
Using a dual trace (two channels A/B) oscilloscope capture the following
components and plot them against each other
The following sensors are used for
Lab Scope Referance:
Make Toyota Model 4A-FE
Signal Name Map & Fuel Injectors
Signal Name Map & Fuel Injectors
A= Grounding / Dwell time
B= Voltage spike from collapsing magnetic feild
C= Stabilizing Voltage
D= Idle Voltage
E= Throttle Opening (Increase in air pressure)
F= Throttle Shut (high vaccum)
C= Stabilizing Voltage
D= Idle Voltage
E= Throttle Opening (Increase in air pressure)
F= Throttle Shut (high vaccum)
Explain in detail how these two components relate each other
As the air pressure increases and the map voltage increases so the fuel injectors ground for a longer time (Dwell time) so fuel is being injected
A= Highest voltage induced from the magnets
B= Change in polarity
C= Neutral Point , no voltage induced
B= Change in polarity
C= Neutral Point , no voltage induced
D= Dweel time
Explain in detail how these two components relate each other
As the peacks from the crank sensor become close or frequency increases fuel injectors ground more often because the RPM in the engine increases
Lab Scope
Make Toyota Model 4A-FE
Signal Name Primary ignition & fuel ignition
A= Dweel time/ Change time or primary coil
B= Firing KV when the coil is ungrounded
C= Dweel time of the fuel injector
D= Voltage returning to 12v after voltage spike
B= Firing KV when the coil is ungrounded
C= Dweel time of the fuel injector
D= Voltage returning to 12v after voltage spike
Explain in detail how these two components relate each other
The bigger the dweel time the primary coil kv builds up then fires , fuel injectors fire first
Lab Scope
Lab Scope
Make Toyota Model 4A-FE
Signal Name Ignition voltage & ignition current
Draw the pattern below:
A= No current in coil
B= Max current build up in coil , when coil is ungrounded current drops to zero amps
C= Ground time / Dwell time of primary coil
D= Firing Kv
B= Max current build up in coil , when coil is ungrounded current drops to zero amps
C= Ground time / Dwell time of primary coil
D= Firing Kv
Explain in detail how these two components relate each other
When primary coils ground or driving dwell time , the current graduatly increase in the primary coil , until coil in ungrounded the current drops to zero and the firing kv is produced.
Explain in detail how one of the components would affect otherAs current increases the magnetic feilds build up during coil dwell time
Explain the operation of the sensor or Actuator using the Graph:
(Use arrows at different points, and describe what happens there)
Draw the pattern below:
Explain the operation of the sensor or Actuator using the Graph:
(Use arrows at different points, and describe what happens there)
Lab Scope
Make Toyota Model 4A-FE
Signal Name Rpm/Crank Sensor
Volt/division/range 2v
Time/division/range 20ms
Draw the pattern below:
Explain the operation of the sensor or Actuator using the Graph:
(Use arrows at different points, and describe what happens there)
Explain the operation of the sensors or Actuators using the Graph:
(Use arrows at different points, and describe what happens there)
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