Pinging... what causes it exactly? How is it avoided/fixed?

[Taily]

Originally Posted by Crazy Dazz

How the heck would you get CARBON build up in a modern engine?
Don't get me wrong, I have seen all sorts of crud in heads, but CARBON will simply burn, unless your engine is running way too rich.

Sudden onset pinging is most likely dodgy fuel. Something went out of whack in the blend and its "octane" rating is too low. Your car should compensate for this, but there's a limit to how far it will retard the spark.

If it persists, then I would start to suspect that something has gone wrong with the timing, so you have to start looking at sensors, etc.

Quite easily, besides carbon will not burn unless it is in an aerosol (soot like) state.

Lots of very short distance trips, a thermostat that opens early or has been changed because "cooler is better", dribbling injectors, glazed bores/blowby/faulty PCV etc will all either cause or contribute to it.

You hit the nail on the head about sudden onset pinging. Most likely a load of fuel, however many people see any car without chrome bumpers as "new" so go easy on us...

The noise you all associate with pinging is not the actual uncontrolled burn in the cylinder, it is the piston momentarily rattling sideways in the bore and ringing like a bell...