Backfire

Single backfire, occasionally, on start-up.

As engine is trying to start, starter motor engaged and turning the crank, sometimes there will be a 'muffled' explosion thump-like noise emitted from the engine bay.

Have not isolated exactly where the sound comes from, but have long thought it was inside the air intake tube, prior to the throttle body.

Problem has long standing, because I never figured it needed attention, being that it happens so infrequently.

When I began a search for information on engine backfires, I happened onto your website, which explained that backfires can cause damage. That is why I signed up.