93, 4.9L 6 cyl, always pings. Changed plugs, wires, cap etc. and then checked timing. Timing was dead on. I took it to a shop, they said the timing was fine and that there was no good reason for it to ping. I ran premium gas all the time. Still pings (but not as bad). It's been this way for 3 years. It's an old story I've seen posted many times. It look like I fixed it so I'm passing this on to others to try. I ran my tank almost empty and filled with 87 octane. Drove home (pinging terribly all the way), disconnected the battery and left it disconnected for couple of hours. This reset all the sensor info in the computer. Re-connected the battery and took it for a ride. The pinging is gone. I've been driving it now for three days and no more pinging! The engine appears to have more power than ever before as well. For those of you that have the same problem, try this ressetting of the brain. Hope this helps someone else.

 

Sad news is the pinging will probably come back over time. Check the computer for codes even if the CE light has not been on. A broken EGR tube, rusted air injection tube, broken vacuum line, or exhaust manifold crack could all cause this and no codes would be thrown.

 

my truck is picky on gas i have to run shell or sunnco gas in my 300 or it will ping. i found this out becouse truck always pinged . my gf dad used it and filled it with gas and i drove the truck and no pinging . I asked him where he got gas and he sayed shell. Long story short try a new brend

 

Ping knock can occur when you do not use a high enough octane and it can also occur if you have to much carbon buildup in the engine. I had pretty bad ping knock in a 96 Jeep that I had and what I did was pour about a 1/2 can of seafoam straight into the intake. I did this about three times over a weekend and the solved every bit of the ping knock while allowing me to go back running 87 octane again too. Here is what I did

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Start the engine and allow it to warm up to full operating temperature. Once warmed I slowly poured in 1/2 of the can (very slowly poured) it will make the engine want to choke and die but pour slowly enough not to kill it. Once I got the 1/2 can all in I then shut off the jeep and let it sit for about 10-15 minutes and just soak inside. After soaking for a while I then start it up and let in run. You will see the largest smoke cloud ever for a while since it is burning out all of the carbon.

It is amazing what this stuff will do. For instance I took the spark plug out of my bass boats engine one day and shined in the cylinder with a flash light - the cylinder and plugs were just black as hell and all full of carbon (the number 1 killer of boat engines) anyways, I mixed up 2.5 gallons of gas with 32oz of seafoam and drove around the lake until the entire 2.5 gallons was gone. I then removed the spark plug and shined a light back in there. The plug and the cylinder was bright and shiny just like they were brand new. My engine had never run better in it's life. I run this stuff through everything, I even run a can through my John Deere once a month.
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This won't hurt your engine but sometimes if the carbon is bad enough it can coat the oxygen sensor on its way out the exhaust requiring you to remove it and clean it. I haven't ever had the carbon foul up my oxygen sensor but have heard of some people having to clean them afterwards. <O

 

What are your plugs gapped at? I had this problem on my 300 and I reduced plug gap by .010 and it fixed it. Wide plug gap = advanced timing.

 

jas88: I was not sure if you are asking me, but I have them set to the factory spec. Did you reduce .010 less than spec? I posted that my truck was now running great yet I'm getting suggestions for fixes so I'm not sure why. Anyway, it's still running well.

 

Nah, I had gapped them up to .055 which makes it idle smoother. This was a trick I learned on my '90 F150 w/302. I ran that gap most of it's life with no problems so I did it to this truck. I gapped back to .045 and it fixed my pinging. It used to ping even on premium, now it is quiet on regular.