Back in the day, the earliest exhaust systems were dumb metal linkages. Sure, the welded pipes worked efficiently. They rid the engine of waste gasses well enough, but there was no emissions control in the system. Today’s exhaust pipes are smart by design. They incorporate a special oxygen monitor, an O2 sensor that monitors and controls engine emissions. It’s all about feedback, but what is this control loop altering?

Fuel Mixture

Oxygen sensors (O2) are typically installed in the exhaust manifold. They monitor oxygen because this is the atmospheric gas that mixes with your fuel to generate combustion. Engines are finely tuned so that the bulk of the fuel is burnt and no waste remains, but if the burn ratio is oxygen rich, well, this heavy mix will induce waste. Similarly, a lean oxygen-to-fuel mix also produces pollution. The O2 sensors detect this misbalance and send the data to your engine’s computer, which is when the check engine light starts to flash its warning.

Active Emission Control 

If the fuel/oxygen ratio is out of whack, pollution is produced, but the onboard sensors are always on hand to inform you of this environmental hazard. Technology doesn’t stop there, though, not when the feedback loop is buzzing away to constantly update the burn ratio. The engine computer regulates the mixture, takes its cue from the tiny feedback loop so that it can manage the amount of oxygen entering the combustion cycle.

Safety in Numbers

As emission control standards tighten, the number of oxygen detectors installed in modern vehicles has doubled. For example, there’s an input detector mounted in front of the catalytic converter. It sniffs the input mix while a second downstream monitor takes note of the output oxygen-to-fuel blend. The computer does a little arithmetic, compares the two values, and gives the cat unit an invisible check mark. Both the engine exhaust manifold and the rest of the exhaust system deliver constantly monitored output signals in this manner, all so that the closed feedback loop will keep the burn cycle perfectly balanced.

On the surfaces, O2 sensors seem designed to burn out Engine Check lights and cause you headaches, but their true purpose is to inform your vehicle’s computer, to precisely monitor the fuel/ oxygen mix. If that explosive blend is just so, well, no pollutants are generated, but if it burns too rich or too lean, hazardous emissions will flow. Worse still, your fuel economy will suffer while engine performance drops and key components incur damage.

Trufit Exhaust
437 Warrigal Road,
Moorabbin, VIC 3189
Australia
Areas serviced: Melbourne
Tel: 03 9555 5688

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