WS7 Exhaust Gas Analysis (Petrol only)
Make: Toyota Model: Corsa Year: 1996
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.”
1. With the analyser probe sensing normal air, what are the Four Gas readings? Record the amount and then what it means:
CO: 0.001% means: Carbon monoxide which indicates rich air/fuel mixtures. CO is a byproduct of combustion, therefore, if combustion does not take place, carbon monoxide will not be created. If high CO is measured then too much fuel is being delivered to the engine for the amount of air entering the intake manifold.
HC: 12ppm means: Hydro Carbon which is unburned fuel that remains as a result of a misfire. When combustion doesn't take place or when only part of the air/fuel charge burns, hydrocarbon levels goes up.
CO2: 0.00% means: Carbon Dioxide is a desirable byproduct that is produced when the carbon from the fuel is fully oxidized during the combustion process. As a general rule, the higher the carbon dioxide reading, the more efficient the engine is operating.
O2: 20.9% means: Oxygen indicates a lean running engine since O2 increases with leaner air/fuel mixtures.
2. Start the engine idling cold, and record the Four Gas readings
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: 2.5% HC: 788ppm CO2: 12.6% O2: 5.15%
The CO reading of 2.5% shows that there is a high amount of fuel being delivered to the engine for the amount of air entering the intake manifold. This is because the engine is cold. There is high amount of HC which means not all the fuel is being burnt inside the engine or because the catalytic convertor has not reached operating temperature. The CO2 shows that there is a low amount of misfires and that the engine is running efficient. The 02 readings show that there is a lean air/fuel mixture.
The CO reading of 2.5% shows that there is a high amount of fuel being delivered to the engine for the amount of air entering the intake manifold. This is because the engine is cold. There is high amount of HC which means not all the fuel is being burnt inside the engine or because the catalytic convertor has not reached operating temperature. The CO2 shows that there is a low amount of misfires and that the engine is running efficient. The 02 readings show that there is a lean air/fuel mixture.
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: 0.50% HC: 235ppm CO2: 14.2% O2: 1.10%
CO shows.. HC shows that most of the fuel is being burnt. CO2 shows that the carbon from the fuel is fully oxidized during combustion therefore misfires are low and the engine is running efficient. There is a low amount of O2 produced from the engine which shows that the air/fuel ratio is gone rich of stoichiometry.
CO shows.. HC shows that most of the fuel is being burnt. CO2 shows that the carbon from the fuel is fully oxidized during combustion therefore misfires are low and the engine is running efficient. There is a low amount of O2 produced from the engine which shows that the air/fuel ratio is gone rich of stoichiometry.
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: 0.234% HC: 121ppm CO2: 15.10% O2: 0.32%
HC shows most of the fuel is being burnt.
HC shows most of the fuel is being burnt.
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: 0.961% HC: 224ppm CO2: 14.32% O2: 8.68%
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: 0.029% HC: 470ppm CO2: 7.79% O2: 5.93%
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: HC: CO2: 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: 0.01 HC: 1033ppm CO2: 13.6% O2: 4.53%
The cylinder that the spark plug wire got grounded to could not ignite the fuel in the combustion chamber because it was grounded to the cylinder head. This caused that cylinder to misfire and not burn the fuel that was injected and the air that entered the combustion chamber. As a result the HC ppm levels were as high as 1033ppm which is because there was 1 cylinder misfiring every four strokes and so waste alot of gas and oxygen.
The cylinder that the spark plug wire got grounded to could not ignite the fuel in the combustion chamber because it was grounded to the cylinder head. This caused that cylinder to misfire and not burn the fuel that was injected and the air that entered the combustion chamber. As a result the HC ppm levels were as high as 1033ppm which is because there was 1 cylinder misfiring every four strokes and so waste alot of gas and oxygen.
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: 0.009% HC: 53ppm CO2: 11.61% O2: 5.45%
The engine is running lean. One injector is disconnected and so in that cylinder on the intake stroke only air is entering the combustion chamber. O2 levels are high because it is not being mixed with fuel and burnt in the cylinder with the missing injector.
The engine is running lean. One injector is disconnected and so in that cylinder on the intake stroke only air is entering the combustion chamber. O2 levels are high because it is not being mixed with fuel and burnt in the cylinder with the missing injector.
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: 0.009% HC: 18ppm CO2: 15.44% O2: 0.04%
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?
A vehicle with a catalytic convertor converts harmful HC + CO + NOx into harmless compounds such as H2o, CO2 and N2. A vehicle without one may only reduce some compounds like NOX levels using an EGR valve. But a vehicle without a catalytic convertor does not reduce as much emissions as a vehicle with one does.
A vehicle with a catalytic convertor converts harmful HC + CO + NOx into harmless compounds such as H2o, CO2 and N2. A vehicle without one may only reduce some compounds like NOX levels using an EGR valve. But a vehicle without a catalytic convertor does not reduce as much emissions as a vehicle with one does.
12. Explain what light off point means and what happens?
Light off point is when the catalytic convertor has reached its operating temperature and starts to reduce emissions
Light off point is when the catalytic convertor has reached its operating temperature and starts to reduce emissions
13. On lambda, 02 sensors why do they have 1,2,3,4 or 5 wires and what do these extra wires do?
They have 2 white wires which are heater + and heater - which heat the sensor to get it up to operating temperature so it responds quicker. The 3rd wire is black wire which is a signal wire to the ECU which tells it how much free o2 there is in the exhaust gases. The 4th wire is grey which is the signal earth wire.
They have 2 white wires which are heater + and heater - which heat the sensor to get it up to operating temperature so it responds quicker. The 3rd wire is black wire which is a signal wire to the ECU which tells it how much free o2 there is in the exhaust gases. The 4th wire is grey which is the signal earth wire.
Some good comments.
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