A vehicle’s fuel mixture refers to the ratio of fuel to air in the combustion process. When you have too much fuel and not enough air, your car is considered “rich.” When you have too much air and not enough fuel, your vehicle is considered to be running “continuously.”
The vehicle’s engine computer controls the fuel mixture using oxygen sensors, fuel injectors, emissions sensors, an air/fuel sensor, and air flow sensors. If your car has a rich fuel mixture, you will notice several symptoms:
Top 7 Signs of a Rich Engine
#1 – Check that the engine light is on
If you are using an auto diagnostic tool to scan the check engine light trouble code and it shows P0172, it means that there is excess gasoline in the exhaust when it leaves the combustion engine chamber.
Many instruments are used in the Engine Control Unit (ECU), including oxygen sensors, total pressure, and a mass air flow sensor.
Manifold absolute pressure is used to monitor the engine’s air-fuel ratio. These sensors tell the vehicle’s ECU that there is a problem causing the check engine light to come on.
#2 – Smell
One of the first things you may notice is a strong fuel smell or rotten egg smell coming from the exhaust. This is because excess fuel is not burned properly in the combustion process and escapes into the exhaust manifold and eventually out the tailpipe.
The catalytic converter’s job is to burn off excess fumes, but when the fuel mixture is too rich, the cat can’t even burn off the excess.
See also: 6 reasons why your oil smells like gasoline
#3 – Poor energy efficiency
If you notice that you are not getting as much fuel mileage from your tank as before, it could be a sign that your engine is running well. Basically, you are burning more fuel than you need to keep the car running properly.
Keep in mind that a car will run a little richer than normal in cold weather, so if your gas mileage is a little lower in winter than in summer, that’s normal.
#4 – Poor Engine Performance
Power in a gasoline engine comes from a combination of fuel, air, compression, and then a spark. Without these four requirements, you will not get power from your engine.
Therefore, poor engine performance would mean that there must be a problem in one of these areas.
You can have normal compression and normal spark but still have low engine power. It simply means that there is too much fuel or too much air in the fuel-air mixture.
#5 – High carbon monoxide emissions
Although an exhaust naturally expels some level of carbon monoxide, if your engine is running too rich, that level will be higher than normal. This is often the reason why a vehicle fails a state emissions test.
Additionally, you should be serious about expelling too much carbon monoxide as it can endanger your health, especially if it starts to leak into the car while you are driving. Breathing these vapors for a few minutes can cause serious neurological damage.
#6 – Severe Engine Idle
A rich fuel mixture can cause a rough idle. This means that the vehicle will vibrate and feel a little rough when the engine is running.
Although the car is not moving (position), you may notice that the RPM on the tachometer is behaving erratically, jumping a little. Sometimes vibrations in the engine can be felt while driving.
#7 – Clogged/dirty parts
Two big signs that your engine is running well have to do with the condition of your spark plugs or catalytic converter. When you’re rich, the bottom of the spark plug can become covered with dry, black soot. This is called a carbon deposit and will affect the performance of your engine.
As stated above, the catalytic converter’s job is to burn excess fuel before it reaches the fin tube. The result is often a car fire.
If you have to continually burn excess fuel, it will eventually cause the catalytic converter to clog and the honeycomb design inside it to break down. Once this happens, an expensive catalytic converter replacement will be required.