Question about "pinging"? At least I think that's what it is...
Very occasionally, not often at all, I get what I would describe as pinging or engine knock (though I never thought the word "knock" was appropriate).
I'm familiar with the sound because, years ago, my 2000 Continental would do it on regular gas but not on premium, usually uphill in too high a gear.
The situation when I hear it occasionally in my Thunderbird is this: accelerating at say 3/4 throttle in 3rd gear, potentially sometimes in 2nd. A quick acceleration, but not full throttle; think 3,500 to 3,700 rpm upshifts.
It's a faint ping, and I immediately respond by easing off the throttle a bit. I know I could just try higher octane fuel, but I really don't want to, simply because the engine isn't spec'ed for that.
Doing some reading, I'm guessing that I'm looking at a mild lean condition, potentially due to a small vacuum leak. Thoughts?
There are no codes whatsoever, no odd idle, no roughness, no stalling.
Today, I cleaned the MAF sensor, reset the computer, and added a Rislone fuel system cleaner. I wonder if the removal of the air silencer does cause accelerated residue buildup on the sensor (?).
You all will probably tell me to hunt down a vacuum leak, which ugh, with a small leak, could be extremely tedious. There's a known leak aft of the HVAC check valve, but it's so small that it takes at least all night to lose the vacuum in the HVAC system.
