WS7

Make peugeot 
Model 306xRI
Year 1994


CO means..Carbon monoxide is a indicator of rich air/fuel mixture and shows there is not enough oxygen in the combustion chamber


HC means..Hydro carbon levels show the amount of unburnt or partly burnt particals in the exhaust. misfire due excessive lean and also rich air/fuel ratio.The lower the levels of HC the more efficent the fuel is being burnt in the combustion chamber.

CO2 means..Carbon dioxide is a good by product and indicates good combustion inside the engine and is produced when the fuel is oxidised , a good rule is the higher the CO2 level the more efficient the engine works .

O2 means..high levels of oxygen is a good indication of lean air/fuel mixture because O2 increases as the air/fuel mixture gets leaner , it also can indicate misfire.

Co=0.416% HC=132ppm CO2=13.80% O2=1.16%

The combustion of air fuel mixture is normal. CO2 is a little bit higher but still within acceptable clean emissioni CO2 limit. The engine is running at acceptable emission level because of low CO and O2. But the engine is running  a bit on the rich side and small amount of air fuel mixture is unburned this results in slightly higher HC level. This could also be due to the catalyst converter is not working at cold idle, so reading bad exhaust gases. 


CO=0.650% HC=162ppm CO2=14.08% O2=0.55%

The four reading show the engine running at efficient and idle. Good combustion was take place in the cylinder and exhaust low emission gas as all of four gases are within the parameter of clean emission standard. At this stage, the catalyst converter should start working as the engine is warmed up. air fuel ratio and most of the fuel mixture is burnt.
CO=1.210% HC=115 CO2ppm 13.88% 02=0.36%

The HC is lower  than warm idle, due to the engine need more fuel to run at high speed. The engine is running at cruising with no load, due to the CO is low. The CO2 and O2 represent the combustion is good and most of air fuel mixture is burnt .
CO=4.485% HC268ppm C02=11.97% O2=0.37%

The HC and CO are high to tell us the air fuel mixture is rich, due to the combustion is incomplete, so large amount of air fuel mixture was found in the exhaust gas. CO2 is low to show the combustion is not perfect as large amount of air fuel mixture have not convert into CO2. The O2 is low to show the catalyst converter used up most of the O2 to convert CO into O2, but the CO is too high, so we still read high CO in exhaust gas.
CO=0.487% HC=136ppm CO2=13.96% O2=0.89%

The O2 is a little bit higher. This indicate the oxygen in the exhaust gases is high. This can be caused by lean air fuel mixture. Larger amount of oxygen fail to condense with fuel and cause the fuel is not condense enough, due to it take longer time to burn all the fuel and create more heat and release more NOx. The CO2 is low which means the combustion is incomplete.

Accelerate the engine by blipping the throttle will cause the engine running rich. High HC and CO show the incomplete of burning, due to the ECU will sense low intake vacuum and inject more fuel into the cylinder. The O2 is high that means the high amount of fuel is unburned in the exhaust gas which is cause by a lean mixture. The ECU will sense high intake vacuum and shorter the injector pulse width to make the mixture lean. Low CO2 is also incomplete combustion in the cylinder.

CO=0.493% HC=3004ppm CO2=9.17% O2=7.78%

The ignition misfire will cause high HC and O2 and low CO2, due to one of cylinder is misfire and all of the fuel mixture is unburned into the exhaust gases. The Carbon monoxide is normal, due to the air fuel mixture is normal and no exceed HC. This is not lean misfire because the HC is high and no combustion was taking place in the cylinder.


CO=0.198% HC=337ppm CO2=9.39% O2=7.82%

The cylinder is misfire, due to no fuel inject in the cylinder. The oxygen sensor will sense a lot of oxygen in the exhaust gas and send a signal to ECU to demand more fuel, this cause the exhaust gases read high HC. The O2 is low as there is only three combustion take place.
CO=0.74% HC=181ppm CO2=14.5% O2=0.62%

The HC is getting lower, due to the engine need more power to turn on the air condition and steering wheel. The more fuel inject to give the engine more power to maintain its idle speed. The CO2, CO and O2 are within parameter and complete combustion was taking place in the cylinder. Beside that, the ECU will open more the idle valve to allow more air to flow into the intake manifold to increase the idle speed.
The catalyst converter has Rhodium, Palladium and Platinum that covert HC, NOx and CO into harmless CO2 and H2O. Thus, the vehicle with catalyst converter emit low HC, NOx and CO and the vehicle without catalyst converter emit high level of NOx, HC and CO gases. 
260 degree Celsius is the temperature at which a catalyst conveter start to work and this temperature point is called light off point. At this temperature the catalyst converter is only 50% efficient . The catalyst converter is only 100% efficient when the exhaust temperature reaches 482 degree Celsius to 871 degree Celsius. When the temperature reaches the light off point, the exhaust gas analyzer starts reading the levels of CO, HC and NOx. When the catalyst converter is warming up, the reading of CO, NOx and HC are low, this means the catalyst converter start to convert HC, CO and NOx in to CO2 and H2O.
Zirconium and titanium oxygen sensor usually have 1 to 4 wires. Generally there are three types of oxygen sensor, the oxygen sensor with heat element, the sensor without heat element and wide band oxygen sensor. The heat element sensor has 3 or 4 wires which are power for heater, ground for heater, oxygen output signal and ground for oxygen sensor. The oxygen sensor without heat element has 1 or 2 wires which include ground and another one is output signal. Wide band oxygen sensor has 5 wires and they are power for heater, ground for heater, two sensor signals and one ground wire for both sensors.