Make TOYOTA Model CORSA Year 1996
Today's computerized engine control systems rely on inputs from a variety of sensors to regulate engine performance, emissions and other important functions. The sensors must provide accurate information otherwise driveability problems, increased fuel consumption and emission failures can result.
One of the key sensors in this system is the oxygen (O2) sensor. It is often referred to as the "O2" sensor because O2 is the chemical formula for oxygen (oxygen atoms always travel in pairs, never alone).
The first O2 sensor was introduced in 1976 on a Volvo 240. California vehicles got them next in 1980 when California's emission rules required lower emissions. Federal emission laws made O2 sensors virtually mandatory on all cars and light trucks built since 1981. And now that OBD-II regulations are here (1996 and newer vehicles), many vehicles are now equipped with multiple O2 sensors, some as many as four!
The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust as the exhaust exits the engine. Monitoring oxygen levels in the exhaust is a way of gauging the fuel mixture. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen).
A lot of factors can affect the relative richness or leanness of the fuel mixture, including air temperature, engine coolant temperature, barometric pressure, throttle position, air flow and engine load. There are other sensors to monitor these factors, too, but the O2 sensor is the master monitor for what is happening with the fuel mixture. Consequently, any problems with the O2 sensor can throw the whole system out of whack.
(Reference) http://www.aa1car.com/library/o2sensor.htm
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: you have a rich condition you don't have enough O2 to create CO2 this means you get CO2
HC: 12 ppm Means: HC is unburnt petrol a higher control indicated a misfire or cold start
CO2: 0.00 % Means : Efficiency should be around about 15%
O2: 20.90 % Means: rich means lower O2 level however O2 means mixture more O2 means lean mix.
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 788 CO2 12.6 O2 5.15
When the engine is cold it has to run richer air fuel mixture this means greater HC.
when rich to much fuel cant burn all the petrol. this levees a leak of O2 and this means
that there is high CO level .CO2 refers to the efficiency of the combust when CO2 is at 15 %
then combustion is at its most efficient.
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 0.001 HC 37 CO2 15.16 O2 0.42
CAT working therefore engine is running efficiently and HC and O2 low as almost
all of the fuel is being burnt since it is now highly fuel efficient .
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 121 CO2 15% O2 0.32
At 2500 rpm there is slightly richer mixture this means greater HC due to unburnt fuel however
combustion is still efficient so there is low O2 and also there is more CO due to to richer
air/fuel condition.
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 224 CO2 14.32 O2 0.68
Engine is running rich so higher HC due to unburnt fuel and engine is less
efficient.There is higher O2 as there is too much fuel to burn.
This also means higher CO levels due to the rich condition.
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 470 CO2 7.79 O2 5.93
HC is high as it is harder to burn fuel with greater are ratio this does mean a reduce
is CO as there is more O2 for CO to attach to create CO2
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 2.5% HC 435 CO2 10% O2 1.3
By blipping the throttle there is a richer air/fuel ratio this creates higher
HC and higher CO 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 0.01 HC 1055 CO2 13.6 O2 4.53
HC is extremely high as one cylinder is not firing and all the gas is unburnt
and coming into the exhaust .
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 0.00 HC 55 CO2 11.61 C2 5.45
No petrol is going into one of the cylinder so less unburnt gas and lower HC
This creates higher O2 so there is less Co.
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 18 CO2 15.44 O2 0.04
The A/C unit brings the rev of the noter up more this makes the engine even more
efficient than when at idle so there is low HC and low CO as fuel being burnt efficiently .
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 without a cat converter would produce greater CO and HC as the CAT converter
creates a chemical reaction to change the emission into something different that is less
harmful to the environment.hence why HC and CO are significantly lower on vehicle with
CAT converter.
12. Explain what light off point means and what happens?
In order for CAT converter to work it has to be hot enough to work.
A cat converter is a device used to reduce the toxicity of exhaust emissions from
the internal combustion engine morden car engines control amount of fuel they burn.
13. On lambda, 02 sensors why do they have 1,2,3,4 or 5 wires and what do these extra wires do?
Two cell, 5- 7 ( bosh and some Honda )
one cell 4 wire( Toyota some Honda others)
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