BMW represents the pinnacle of German luxury cars, but even the most quality-made and well-designed vehicle will begin to fail, given time and poor maintenance. Engine misfires in the BMW are common with wear and tear. In this article, we will take a closer look at what happens during engine misfires, explain what causes the problem, and discuss how you can prevent it from happening in your BMW.
To understand engine misfires, let’s first understand the combustion cycle in your engine. Most engines follow a four-stroke or four step combustion cycle to achieve drive. This cycle is continuous and consistent, ensuring constant momentum and is as follows:
1. First Stroke: Intake
The inlet valve opens allowing a mixture of air and fuel to enter into the engine. To do this successfully, the cylinder, piston, and crankshaft need to work together.
2. Second Stroke: Compression
The inlet valve now closes and creates a firm seal which then causes the piston to retract backwards into the cylinder, creating large amounts of pressure which causes the air and fuel mixture to increase in flammability.
3. Third Stroke: Power
This is when the magic happens! The ignition coil converts low voltage electricity into high voltage electricity which it supplies to the spark plugs. The spark plugs then do what they do best and create the spark needed to ignite the pressurized fuel. This ignition releases lots of energy in the form of hot gas which makes the piston drop back down from the cylinder, allowing the gas to escape the engine, where it can power the crankshaft, which allows you to drive your BMW.
4. Fourth Stroke: Exhaust
The final stage allows the burned up fuel fumes to exit your vehicle. To do this, the outlet valve opens. This allows the emissions to exit your vehicle through the catalytic converter and exhaust pipe. The engine system will then revert back to the intake stage so that the cycle can repeat.
If an error occurs in any one of these four strokes, then what is known as a misfire will occur. This is effectively an interruption of the combustion cycle, which can cause it to falter or pause momentarily, such as when your vehicle stalls, or stop it entirely.
There are 3 types of misfires, and each represents an error in different stages of the process. Lean misfires occur when the ratio of air and fuel in the engine is misaligned, whereas ignition misfire occurs when there is a fault in the power stage of the cycle. Finally, mechanical misfire can occur at any stage of the process and is usually due to a failure in any of the mechanized parts, such as the pistons.
Misfires can mostly be avoided with good maintenance and positive driving habits. However, sometimes faults will simply occur no matter your efforts. So listed below are some of the most common causes for frequent misfire:
1. Clogged or Faulty Fuel Injectors
Fuel injectors need to be cared for and serviced regularly to prevent then deteriorating with age. The number one way that fuel injectors fail is through blockages in the nozzles. These blockages affect the amount of fuel that can enter the engine, ultimately resulting in lean misfires.
2. Electronics and Wiring
Your engine uses 2 key electronic parts in the ignition process: the ignition coil and the spark plugs. Both parts work closely together to ensure successful ignition of fuel, but they can also have a negative effect on one another should failure occur. One part often compensates for the other and becomes worn out in the process. These two components are the main culprits when it comes to ignition misfire.
3. Crankshaft Failure
The crankshaft is integral for insuring the combustion cycle is successful, and because of this, your BMW’s onboard computer monitors this part closely using a sensor to gauge its position and rate of rotation. If the sensor becomes faulty, the computer won’t be able to monitor this information, resulting in mechanical misfires.
If you’re a resident of Carrolton and Dallas, TX, expert auto servicing is just a short drive away. The friendly and efficient experts at Ultimate Bimmer Service know what it takes to ensure your BMW remains misfire-free and performing at its best, so book your servicing appointment with us today.