WS7 Exhaust Gas Analysis

Make Toyota Model Camry

Exhaust Analyzer should be warmed up and recently calibrated. When it’s time to start taking tailpipe readings, put the analyzer 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.”

Normal air

CO(carbon monoxide): 0% in the air.

HC(Hydro Carbon): 4ppm(part per million) have little bit unburnt fuel in the air may be caused previous car tested.

CO2(carbon dioxide): 0.02% in the air.

O2(oxygen): 20.91% means the air still clean not much pollution around.



Start the engine idling cold

2 things important when engine cold start HC and O2. When cold condition to keep the engine running, the engine needs more Hydro Carbon or petrol than oxygen in the combustion. Some of unburnt petrol is causing the Hydro Carbon reading getting high in tailpipe. For CO and CO2 still  acceptable. The lambda saying is rich mixture.




Run the warm engine at 2500 RPM

The engine is running rich. High CO, Lambda, Hydro Carbon and  low O2 are the signs of the engine running rich. Hydro Carbon high means still unburnt petrol in the combustion because the RPM to high, lots of petrol spraying by injector to combustion.


At idle, run the mixture rich with extra propane, LPG, or carburetor cleaner

Without MAP sensor for this case, ECU think the vacuum in the intake manifold is minimum and in the mean time automatically the ECU think the throttle open wide and ECU will send the signal to the injector to spray more fuel in. This Hydro Carbon is high because unburnt fuel. High CO cause low CO2 means the engine running rich.


At idle, create a lean condition with an air leak or vacuum leak

High O2 in exhaust gas shows the engine is running lean, and high Hydro Carbon means its running rich. But high Hydro Carbon does not mean that its running rich because low CO and CO2 values with high Hydro Carbon means the fuel is not burning properly because of vacuum leak.

Accelerate the engine, by blipping the throttle a few time

CO and Hydro Carbon are high and CO2 low means the fuel is not burning properly because of lack of sufficient O2 for proper burning because blipping of throttle sucking less air as compare to fuel going into the cylinders. Blipping is not perfect mixture because volume of the air and petrol changing all the time.



Disconnect one spark plug wire, ground it with a jumper wire

Hydro carbon and O2 little bit high because the miss firing and unburnt fuel in one cylinder. CO2 is low and lambda is high because O2 is high.


Disconnect the injector harness connector from one injector on an engine

There was unbalance firing the cylinder can be causing misfiring in between cylinder order; this case make the Hydro Carbon bit higher. 


The engine at idle, turn on the air conditioning or rocking the steering wheel.

When the air conditioning on and rocking the steering wheel, the engine need to turn the pulley for air conditioning means engine get the extra job or load; automatically the RPM getting high little bit and down after few seconds but the engine needs more petrol coming into combustion. And not much air coming in because idle. The Hydro Carbon quiet low enough because the engine hot enough.


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?
Vehicle with a catalytic converter,  CO and O2 would be low and CO2 would be high and vehicle without catalytic converter, CO and O2 high in the exhaust gas and CO2 would be low. Because the catalytic converter has a job reduce the harmfull gas produced by combustion. And causing pollution in the air. 


12. Explain what light off point means and what happens?
The light off point means the catalytic converter will be working in certain temperature in range roughly 200-300degrees Celcius. When the catalytic converter is working the engine will be running in efficiency condition.  


13. On lambda, 02 sensors why do they have 1,2,3,4 or 5 wires and what do these extra wires do?
1 wire: 1 signal wire and ground using the body of the sensor.
2 wires:  1 signal wire and other wire to the ground.
3 wires:  1 signal wire,  ground wire and heater wire.
4 wires: 2 signal wires and 2 heating element wires.
5 wires: 2  signal wires,  ground wire and 2 heating element wires.