Your engine could be making a popping noise due to a broken spark plug. On certain engine's it was a common breakdown. When the spark plug breaks it will shoot up out of the spark plug hole, when it does this is will damage the ignition coil and possible other components. To fix this we have to repair the spark plug hole that is damaged. We will also recommend a complete tune up with all spark plugs, ignition coil boots unless it has been done recently.
Give us a call and let us take care of you.