Have you noticed that a weird knocking sound is coming from your vehicle, but you're not sure what it is? You'll likely want to have a mechanic or auto service—like an Alfa Romeo service center—take a look to figure out what is wrong. Here are some potential reasons that you could be hearing this odd sound.

Incorrect Air To Fuel Ratio

Your engine needs the proper amount of air and fuel for combustion to happen. If your vehicle is combining the wrong mixture of air and fuel it will cause poor combustion. This will often result in a knocking noise that is coming from the engine. 

There are many reasons why you could have a bad air to fuel ratio. For example, the fuel pump could be going bad and cause the engine to not receive the amount of fuel that is necessary. There could be a throttle position sensor that has gone bad and does not allow the right amount of air to get into the engine. You'll definitely need a mechanic to look into this problem further. 

Low Fuel Octane Rating

Have you noticed all the different grades of fuel at the gas station? These are given specific numbers for the octane level, with a higher octane being higher performance gasoline. It's possible that your engine requires a higher octane rating of fuel, and you are putting low octane fuel into it. Make sure that you understand what your engine requires, because you may actually need to put in the more expensive gas that has a higher octane level. Putting in that cheaper gasoline could impact the engine's performance, which results in a knocking sound from the engine. 

Incorrect Spark Plugs

Were you aware that there are different types of spark plugs for your vehicle? Spark plugs have different properties, such as heat ratings, and your engine requires a specific type of spark plug to accommodate its needs. Incorrect spark plugs can often result in knocking sounds from the combustion process not happening properly.

Damaged Knock Sensor

Many modern vehicles have a knock sensor, which is designed to detect engine knocking and make the necessary adjustments to stop it from happening. The sensor communicates with the engine control unit so that it can make adjustments to the air to fuel ratio on the fly. However, a bad sensor is going to result in those engine knocks not being reported, and there will be no adjustments made to fix the problem.

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