Spark Plug Replacement

When a plug isn't firing cleanly, the cylinder it serves contributes unevenly and the engine can shake or feel lumpy at a stop. A rough idle has several possible causes, so we scan for a specific misfiring cylinder rather than replacing all the plugs on a hunch.

Worn plugs are a common trigger for misfire codes, which the computer stores and often flashes the light for. We read the exact code to see which cylinder is complaining, then confirm whether the plug, the coil, or something else is behind it.

A weak spark can struggle most when the engine is working hardest, so you may feel a hesitation or stumble when you accelerate or climb a hill. Because fuel and ignition both affect acceleration, we verify the cause instead of assuming it's the plugs.

Plugs that are worn or fouled make the first fire of each cylinder less reliable, so the engine can take longer to catch when you start it. Hard starting has other possible causes as well, which is why we check the plugs' condition alongside the rest of the starting system.

An engine misfiring or running on weak spark wastes fuel, so you may notice fewer miles per tank without a clear reason. Economy drifts for many reasons, so we treat a drop as a clue to inspect rather than a diagnosis on its own.