Hello everyone. This is my first post here however I lurked through this forum quite extensively about a year ago when trying to solve this pinging issue.
We have a 2002 Ford Ranger XLT, 3.0L Automatic. For the past several years, it has pinged, constantly and consistently, every mile of every trip, ever.
If you put premium gas in it it would be better, but even that wouldn't eliminate the ping.
I did so much work to attempt to fix the problem. Cleaned, then replaced the MAF, tried the "hot water bypass" mod, which I found on the 2002 does nothing really, because the hot water line only wraps around the EGR, seafoamed (which helped for like, ten minutes) and then seafoamed again (with no change), replaced plugs and wires... really everything I could think of that could be related, O2 sensor, air temp sensor, plugs and wires, of course... all of that I replaced. Nothing helped, at all.
At that time I found somewhere that the apparent problem was a poor design in the heads of the truck, and that sharp edges allowed carbon buildup to occur. The solution was to pull the heads, chamfer them, and reinstall. I never did that of course.
The other solution someone proposed was a water injection system, to keep the combustion chamber free of carbon buildup. That also sounded like a way-too-complicated system.
Fast forward to a few days ago, when I took the truck in for the well-known valve body gasket problem. I have had the new separator plate since April and I never put the damn thing in, and finally decided to just bite the shop fee so it would be done.
$400 later, no transmission problems. But what I also noticed before I got out of the parking lot was that the truck wasn't pinging.
And then it still wasn't pinging.
And then it didn't ping some more. I thought it was just happy, since it just came from the Ford Motor Spa, but I started investigating the service ticket.
They had applied a PCM update. That's what fixed the pinging. After all my hours of component swapping they fixed it in five minutes with a handheld terminal without me even mentioning the issue.
So, if you're in the ODB-II year range and have a pinging 3.0L or 4.0L, (the issue exists with both), take it in and have the PCM updated before you replace every damn sensor on the truck.