It means there is detonation occuring in the cylinders. The lean condition is causing the combustion chamber to get too hot therefore when the fuel is squirted into the chamber it is combusted before the spark plug ignites the mixture. More fuel will solve this problem.
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"Beauty is in the eye of the mustang owner"
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Most important thing is to stop it fast. Are you running a custom tune or are you stock? May want to pull your plugs and inspect them for insulator damage.
Pinging can also be caused by bad gas, and also by carbon build up on the heads, valves, and/or pistons, on the spark plugs, and on the EGR valve.
How many miles are on the car?
Also,
Did you install any mods on the car that would have affected the A/F ratio immediately prior to the pinging happening, i.e., new tune, CAI, headers and x-pipe/h-pipe, s/c, etc.?
Did you make any changes to an existing tune's A/F ratio or timing?
Did you install new spark plugs?
Did you use a different brand of gas?
What octane lvl gas are you running? A lot of S197 Mustangs will start to ping at round 5000+ miles using 89 or 87 octane fuel. I switched to 91 and it has solved most of my issue, although I still get a few small rattles here and there, but nothing as bad as before.
My car is also bone stock save for some window tint...
My car developed a nasty case of the pings this last summer. I was driving very conservatively and along with running cheap no-name fuel most likely either the injectors started flowing less (dirty & lean) or I carboned up the combustion chambers (or both). A couple bottles of Techron fuel system cleaner and a little more go pedal solved the pings. Now I am only using Top Tier fuels to try to keep the engine internals clean and prevent a recurrence.
hey thanks for all the replys and help! my bad for not telling you more about my cars setup! so heres my engine setup ! steeda intake, custom dyno tune, using sct tuner, i always use 91 - 93 octane! the pinging occurs at wot at higher rpm,s. so thats the setup! hope it helps with diagnosing my pinging problem! oh yea i have tryed 'seafoam' in hopes curing the problem. still had the pinging. my fuel mileage is pretty decent 18mpg in city and 24.9 on the highway cruise set at 70 mph.
hey thanks for all the replys and help! my bad for not telling you more about my cars setup! so heres my engine setup ! steeda intake, custom dyno tune, using sct tuner, i always use 91 - 93 octane! the pinging occurs at wot at higher rpm,s. so thats the setup! hope it helps with diagnosing my pinging problem! oh yea i have tryed 'seafoam' in hopes curing the problem. still had the pinging. my fuel mileage is pretty decent 18mpg in city and 24.9 on the highway cruise set at 70 mph.
You can try to pull 1* of timing from 2000-4000 and 1* from 4000-8000 and see if that helps.
2007 Mustang GT pinging at wide open throttle... What's causing it?? 
