How long can you drive with bad spark plugs?
How long can you drive with bad spark plugs? Ideally, you should replace them immediately. However, you can get by for a short while, as long as they aren’t misfiring. Poor spark keeps fuel from being burned inside the combustion chamber. This reduces power and fuel economy, and it makes it harder for the engine to idle. The unburnt fuel also puts a heavy load on the catalytic converter. Misfires can lead to engine knocking. This is when the air/fuel mixture ignites when it isn’t supposed to. If the fuel burns at the wrong time, it can damage the piston and valves.