1993 Toyota Corolla Corolla 93 4afe engine pinging sound

Check the timing by crossing Te1 and B1 of the diagnostic port, check timing on the balancer pulley marks. Should be 10 degrees BTDC. If not adjust dist. to proper timing.
Make sure you are using correct plug and heat range.

Remove and inspect plugs for overheating.

If all fails from above, you may have a bad ECM, but if you can find a shop that can scan live data, you can see if the ECM is commanding excessive advance.
It is also possible the dist. has excessive clearences' and would need to be replaced. Find a used one at a junkyard and install it, see if pinging stops.

Other possibilities are excessive carbon buildup on pistons or bad gasoline.

You may also be confusing the sound of excessive shim clearence on the valves with pinging.
Check valve clearence on all valve shims. Make sure engine is cold to do this.

Hello,

Good day to you. I had my timing checked and the dist. is adjusted, the timing is now 10 degress from 8 degrees BTDC and I also checked the plugs and it all looked good but still pinging continues.

I tried to check the PCV valve and hose because the noise is like coming from the cylinder head. I removed the PCV valve and the pinging stops.

I replaced the hose and the PCV valve and pinging still continues. What could be causing this pinging sound? Could it be the air in the cylinder head is too much because when I remove the PCV valve together with the hose...the pinging stops.

Please Help me.

Thank you so much and more power.

Try a tank of high octane gas. if pinging stops then it is a carbon build up issue.

If it continues, then an excessive vacuum issue, cause by a blockage to one or more vacuum lines. Normally when you remove the PCV valve with engine running it will run rougher.
Remove valve cover and check for sludge build up around PCV port.
Install vacuum gauge to intake manifold and come back to us with gauge readings e.g. steady reading, large, small fluctuations at idle and when you "blip" the accelerator pedal.

Good day to you!

I tried removing the cylinder head and cleaned the port where the PCV valve is inserted. I cleaned it
with a carb cleaner and I also cleaned the throttle body again and the vacuum lines and after 10 minutes of idling the RPM went normal, the engine was never as quiet as before, and after almost an hour of test driving, the engine runs smoother and the pinging is gone. Thank you so much for your help, everything is very much appreciated.

One more thing...is it ok if I tighten up the cylinder head screws/nuts? will there be a problem in the future if the screws/nuts are real tight?

Thanks again and more power to y'all.

You are talking about the valve/cam cover bolts, not the cylinder head bolts. Tighten them with a 1/4" inch drive socket and ratchet, "snug" and even.

if there was sludge buildup in the cam cover, you are not changing oil/filter every 3,000 miles.