5 Symptoms of a Rich Air-Fuel Mixture in Your Car

Last Updated on June 24, 2019 by themechanic

The internal combustion engine must have the proper ratio of air and fuel before the mixture of the two can be ignited in the cylinders. Otherwise, the engine won’t be able to generate the proper amount of power needed to move the vehicle. There are various sensors and components in the vehicle which work constantly to ensure there is a proper balance in this ratio. Some of which include the emissions sensors, airflow sensors, fuel injectors, oxygen sensors, and the engine control unit. When they’re functional and working smoothly, you will never have too much fuel or air in the mixture prior to combustion.

However, if there is ever excessive amounts of fuel and low amounts of air in the mixture, then you’ll have what is called a rich air-fuel mixture. Alternatively, if you had the opposite problem where there was more air than fuel, it would be called a lean air-fuel mixture. Each one can be devasting for the performance of your engine. Here, we will discuss the outcome of a rich air-fuel mixture.

5 Common Symptoms

A rich air-fuel mixture has certain symptoms which will present themselves. Once you learn about what these symptoms are, you will be able to distinguish them from the symptoms of other possible issues that can affect the combustion process.

Below are the top 5 symptoms of a rich air-fuel mixture in your car.

1) Foul Stench

The smell of rotten eggs will come from your exhaust system. It is kind of hard to miss this symptom because the smell in your passenger cabin will be less than pleasant. This smell occurs because you have too much fuel in the air & fuel mixture that is getting ignited inside the cylinders. The fumes from this combustion end up in the exhaust manifold, where it then finds its way through your tailpipe and into the outside world.

2) Check Engine Warning Light

The Check Engine Warning Light can mean any number of issues are wrong with your engine or the internal combustion process. If you were to run a diagnostic check on your vehicle once the Check Engine light comes on, you may see warning code “P0172.” This code signals that your exhaust gases have too much gasoline as they’re emitting from the combustion chamber.

3) Weak Engine Performance

Engine performance depends on the right air-fuel mixture as well as the right amount of spark and compression. If any of these areas are lacking or imbalanced, it throws the engine’s entire performance out of whack. Then you will have a weak performing engine which affects your ability to accelerate the vehicle. This can happen whether your engine has too much air or fuel.

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4) Weak Fuel Efficiency

If your gas mileage is suffering from some unexpected reason, then it means you have an engine that is running rich. In other words, your engine keeps burning excessive amounts of fuel when it is not needed. Suddenly, you’ll find yourself spending more money on gas than normal. You need to balance the air-fuel mixture to correct this issue.

5) High Levels of Carbon Monoxide

Exhaust systems always emit some amount of carbon monoxide. However, if you have a rich air-fuel mixture in your engine, then your exhaust system will emit much higher levels of carbon monoxide than normal. For this reason, vehicles with rich air-fuel mixtures end up failing their emissions tests when they get them done. Too much fuel getting burnt means extra amounts of carbon monoxide will form. This causes not only environmental issues but also health risks to you and your passengers too.

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