Auto Care FAQs by Carter Volkswagen: What Causes my Engine to Misfire?
When all is well in your Volkswagen engine, the exact right ratio of air and fuel are combined in each cylinder, and ignited by a spark — and this happens thousands of times every second. Naturally, this requires precise engineering and a well-tuned engine.
Over time, things can subtly change in your engine that can cause a misfire. In a misfire, the mixture of air and fuel isn't properly combusted. This will cause a momentary roughness in the engine you may or may not notice. And if the misfire is severe enough, the check engine light may turn on in your dash, indicating a problem.
Any misfire will cause your engine to waste fuel and generate less power. For that reason, it's a good idea to have an engine that's misfiring looked at by the pros. On this page, we've compiled some of the most common causes of an engine misfire.
Engine Misfire Causes: Bad Spark Plugs
By far the most common cause of an engine misfire are bad spark plugs. A spark plug in each cylinder of your engine converts an electrical impulse into a spark that ignites the fuel and air mixture. Over time, the spark plugs will wear out — though modern spark plugs are rated to last as long as 100,000 miles. If the gap between the spark plug's electrode and body has worn too wide, a spark may fail to jump between them. Or, corrosion, rust and oil could build-up on the spark plugs and keep them from firing correctly. If that's the cause, you'll simply need an engine tune-up to have all the spark plugs replaced.
Engine Misfire Causes: Failed Spark Plug Wires
It's also possible that electricity isn't getting to one or more of your spark plugs at all. That could be due to failed spark plug wires on some older Volkswagen models. However, modern Volkswagen cars lack spark plug wires. Instead, they're integrated directly into the ignition coils. These ignition coils can also go bad, and lead to a misfire.
What Causes Engine Misfires Besides Bad Spark Plugs?
If changing out your spark plugs and ignition coils still doesn't fix the misfiring issue in your car, don't worry. The factory-trained technicians at your local Volkswagen dealer can get your car running properly again. But this can be a tricky problem to diagnose. Other potential issues could be a weak battery, a vacuum leak, a clogged fuel filter, a failed fuel pump or even an issue with the engine control computer unit.
Since engine misfires can be tough to diagnose, and cause your car to waste more fuel, perform poorly and pollute the atmosphere more than necessary, this is an issue you'll want to have addressed by the professionals soon. Be sure to turn to an authorized VW dealer when it comes to these important services.