if your engine pings, it's the feeling of your engine getting stressed, insted of doing useable work, it's hard on your bearings, and stresses your pistions, and it has no positive side affects, not even little ones that I know of.
I'm a bit of an automotive hypochondriac (immediately assume the worst whenever some new sound appears, or the car doesn't idle like it normally does...), so maybe I'd be better off not hearing the noises that I couldn't otherwise hear.
Here's a serious question though: exactly how bad is pinging? EG: If I have my timing set so that I'm just beneath the ping threshold for 98% of my driving, but it does ping on those rare occasions when I load it up (say on a really steep hill, or to accelerate faster than usual), am I playing with fire? Going to wreck the engine?
The more dramatic term for "ping" is "detonation" -- basically the fuel igniting at the wrong time and not having the piston in the right spot to move (some people call it "spark knock". Constant ping will destroy an engine as Ryland put it: extra, undue forces on internals. Rare ping is normal, but I'm like you -- if the car idles funny or pings, I immediately begin the diagnosis and treatment. A common fix for the troubled pinger, is to do a carbon cleanse, adjust that timing, or go up a grade in octane rating. But if you have it happen occasionally, then that's entirely normal. We're talking over 50,000 miles of serious, constant ping to destroy a well-built engine.
Causes range from poorly tuned timing to a abnormal build-up of carbon or even high intake or coolant temps. Ford Crown Vics/Grand Marqs were notorious for building up so much carbon that the engine would ping itself to death. My Father-in-Law's old G-Mq had so much carbon in the intake manifold that it split, spewing raw fuel all over the engine. No fire was started, but at the time, he did trade it on a new 2005 Civic LX Sedan upon the advice of an unnamed son-in-law (and he loves it). Take a ride in a cab and you'll see what I mean. Law enforcement agencies use seafoam or pure water to clean the carbon out of their Crown-Vic units to get them to last forever, so they ping less commonly.
Moral of the story: unless you experience ping every time you drive the car, then I wouldn't worry about it. Otherwise, perform some of the above maintenance.
Speaking of paranoid, I noticed for the first time ever that a belt is slipping after a FAS startup. It's just a chirp, but it makes me nervous. I hope it's an isolated, weather-related event. All the belts were replaced last year...
I think the occasional ping is ok. Many street tuners that I spoke with while I was building my turbocharged Civic told me that they will tune the timing maps by adding timing in each RPM/load cell until they detect small amounts of detonation, then back off a few degrees and leave it there. Dyno tuners will do the same but look for a small loss in power, then back off a few degrees. Remember that your engine will continue to make more and more power all the way up to the detonation threshold.
I used to have an MGB that had a vernier timing adjustment knob on the side of the distributor called the "octane selector." It's purpose was to enable you to advance the timing until it pinged when you tromp on the gas in 4th gear at ~20 mph. - and then back it off a little.
Reality is merely an illusion, albeit a very persistent one. - Albert Einstein
Cool. I would like to have a knob like that on the dashboard.
I'm told that modern engines (at least in Hondas) have an "octane sensor" that sorts this all out automatically -- so if your car requires premium and you put regular in it, it automatically adjusts timing. It could be a fancy name for a knock sensor -- not sure