Daihatsu Sirion Engine Problems
Ask Smithy Xtra noisy Daihatsu Sirion
What the mechanic told you is rubbish, there has clearly been a change in the way the engine is running, and that suggests there’s a problem. Changing the spark plugs, they’re located in the cylinder head, and the spark leads is a good idea. If you’re not sure take the car to an auto store and they will show you the plugs and leads and supply you with replacements.
Back to the Mechanic
IT COULD be the plug leads, or the ignition coil, even a sensor. Have your mechanic check it again.