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Mercedes Repair: Engine Misfire Issues

Mercedes repair

Does your Mercedes-Benz have a rough idle? Have you noticed a significant drop in power? Maybe your face is basking in the glow of a check engine light? Your Mercedes may be suffering from a misfire issue. While this may sound scary at first, a Mercedes repair center can quickly diagnose which cylinder this misfire is occurring in and what the cause is.

What Is An Engine Misfire?

The normal operation of an engine requires the correct air-to-fuel ratio to be ignited when the piston has fully compressed the air-fuel mixture. If the spark plug is triggered too early, too late, or not at all, this causes a misfire. If the exhaust valve is open during a late ignition, it often results in a loud pop, and even a flame popping out the exhaust.

Common Ignition Repairs For A Misfiring Mercedes

Mercedes-Benz are known for their build quality; most engine misfires develop because of poor maintenance. While many owners are good at replacing wear and tear items such as fan belts, oil pumps, and filters, much of the ignition system is often neglected.

Spark Plugs

Worn spark plugs are the most common cause of a misfire, as they can corrode. This can cause the gap between the electrode and ground to increase and not offer a sufficient spark or fail to spark at all. This can be easily repaired by replacing the spark plugs.

Order Of Fire

Spark plugs aren’t the only ignition culprits when it comes to a misfire. The order in which spark plugs are fired is controlled by either the car’s Engine Control Unit (ECU) via coil packs, or by a distribution cap. If a coil pack has failed, the spark plug will not receive any electric current to trigger a spark. In this situation, it’s a simple case of replacing a coil.

Damaged ECU

If both the spark plug and coil pack are working properly, the line between the ECU and coil pack may be damaged and causing a short circuit. Similarly, if a line between the distributor cap and spark plug is damaged, the spark plug may not be getting a sufficient electrical current and will require the leads to be replaced or repaired. Distributor caps can become misaligned as your car ages and can cause the timing of the spark plugs firing, or the firing order to be off. The most common failure we see with distributor caps is the distributor shaft becoming stuck, or the rotor corroding.

Fuel System Repairs To Solve A Misfire

If your Mercedes misfires are mostly noticeable when idling or driving at low speeds, your fuel system may be the cause. A misfire can be caused when not enough fuel is entering the cylinder, throwing off your air-to-fuel ratio. To diagnose a misfire caused by the fuel system, a Mercedes repair mechanic will first test the fuel pressure level of the system. Poor fuel pressure can be caused by a worn fuel pump or damaged fuel lines.

In some cases, fuel injectors can fail, or become blocked, which will lead to fuel not entering the cylinder. In cars that have developed a misfire after standing for a long time, replacing the gas in the fuel tank can resolve the misfire, as bad gas is not as combustible as it should be.

Expert Mercedes Repair

Foreign Affairs Motorwerks has a team of dedicated Mercedes-Benz repair specialists that can easily resolve any issues your Mercedes may be experiencing. We also offer you the best advice when it comes to maintaining and modifying your car. For all your automotive needs, think Foreign Affairs Motorwerks South Florida’s Premier Auto Repair, Performance & Race Facility since 1978.

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