There should be two O2 sensors. It could very well be coated with carbon from burning oil.

 

If theres a chance the ping could be caused by carbon buildup in the combustion chamber/s, plain old water will work as well, or better than snake oil like seafoam does, when aspirated into the intake.

Needs to be applied by someone with experience though, to prevent possible hydrolock damage.

I'd definitely look to the 02 sensor, if not recently changed.

I think only the first 02 regulates mixture though. Second one, if equipped, checks the efficiency of the cat.

 

We used to use water or ATF down the intake for de-carboning chambers. ATF works great, it softens and dissolves carbon without having large chunks getting stuck in a valve, but smokes badly while doing it. Had to stop using it when catalytic converters came along though. There's better chemicals at auto parts shops now, this was the old school method.

 

There's one on either side of the catalytic converter. One is only a few years old and the one I repaired the wiring on could very well be the original, it's after the converter. Just don't know if that would even have anything to do with my problem but now that I think back, it seems the pinging started after I had the stolen converter replaced. What happened was that the jerk who did the job broke the clip which held the o2 sensor's wires, letting them touch the hot pipe. They melted and I had a check engine light for months accompanied by pinging. My first thought was that it was a bad knock sensor. Found out there's no knock sensor but I did repair the wires to the o2 sensor which turned the check engine light off.

 

In an older motor, no, a quart in 4-5 thousand isn't crazy. Old motors leak and breathe a little. Not to mention PCV vapors. Yes, through ONE cylinder, sure, it's excessive. I doubt the oil "use" is one cylinder's work. And a 92 wouldn't necessarily have two O2 sensors. I believe until 96, federal emissions standard equipped trucks came with one. Should be pre-cat.

 

This 92 has 2 o2 sensors. It's a California truck. Maybe I'll replace the PCV valve while I'm at it! Man, I've wasted too much time...Maybe I'll test the o2 sensors for the fun of it! Grab a few cold beers. Anything but go back to the mechanic. Anything! Thanks for the help guys.

 

So I've searched around and found that people with 22re's will install a 180* thermostat in place of the stock 190* to reduce pinging with good results. I swapped in a 180* and the pinging is noticeably less. Not gone but less. I did discover that when the engine is cool and I jump on the freeway in the morning there's no pinging whatsoever until it warms up, no matter how hard I get on it. I'm also running premium gas now so I've got it to where it only pings if I lug it. But nonetheless, it still does it.


So far in the last few months:
Checked EGR...fine
Set timing to 5* (yes, with connector shorted)
All new factory cap, rotor, wires, plugs
Vacuum lines inspected and connected correctly
Intake ducts, air flow meter, hoses inspected...fine
Timing chain and gears replaced
180* thermostat
91 octane gas


So It looks like temperature is a factor. Cooling system works fine, even cooler with the new thermostat, temp gauge reads 1/4 or less. I'm thinking about replacing the fan clutch as the mechanic recommended replacing it about 2 years ago. He also said that the coolant temperature sensor could be suspect as far as what's causing pinging. Any thoughts? Thanks

 

You could check the coolant sensor for the ECU per the FSM. Should be the one on the right below your throttle body. Might as well, you've done a lot!