What causes a spark plug to backfire in a car?

Backfiring is the process of a spark plug, or multiple spark plugs, igniting the fuel in their cylinder out of turn, in a part of the combustion process where the exhaust valve is open on that cylinder. Here are some causes of that delayed detonation that may clear it up a bit more.

What happens when a spark plug is wrong?

Incorrect Timing In order for an engine to run properly, spark plugs must produce a spark at the right time, or the fuel and air mixture will not be ignited properly. When ignition timing falls out of sync, the spark is produced at the wrong moment, which can result in the fuel being ignited while the intake valve is still open.

What should I put in my boot when I change the spark plug?

A very light smear of silicone dielectric grease inside the boot sometimes helps when seating boots. The grease also helps the next time you pull the boots off the plugs, which might be after several years and many miles of service, when the boots could otherwise have baked onto the plugs if not for the lube.

Can a turbo charger cause a backfire in a car?

A backfire condition can also occur in race cars using a turbo charger which is normal because they push the fuel through the engine which is then ignited in the exhaust system. We will cover the primary occurrence of the engine under load first.

Backfiring is the process of a spark plug, or multiple spark plugs, igniting the fuel in their cylinder out of turn, in a part of the combustion process where the exhaust valve is open on that cylinder. Here are some causes of that delayed detonation that may clear it up a bit more.

A backfire condition can also occur in race cars using a turbo charger which is normal because they push the fuel through the engine which is then ignited in the exhaust system. We will cover the primary occurrence of the engine under load first.

Can a faulty ignition coil cause a backfire?

The same result can come from a faulty ignition coil, distributor or rotor and cause a more repetitive backfire. Car owners usually forget to check the ignition system at the recommended manufacturer schedule. If necessary, consult your car owner’s manual or repair manual.