Luke7

My car recently started making a pinging/engine knocking noise. Only when I'm going up a grade in 3rd or 4th gear with pull on the engine. Plugs are good / replaced less than a year ago with same as originals. It's the sound you would get if the timing was off. Knock sensor? Maybe a weak coil pak? Car runs fine otherwise. Always premium gas so that isn't it. Mileage is still good. Any suggestions? I've reset the computer, no change. Valve adj. needed?

01tl4tl

seeing your signature shows all the normal things are taken care of- I would definetly do a valve adjust now,,or 50kmiles ago~

confirm EGR system was cleaned- intake manifold removed,, and passage and port are cleared?
thats something needed every 75kmiles, especially 99s with only 1 egr port (later years have 6!)
see diy list https://acurazine.com/forums/2g-tl-1999-2003-98/new-official-2nd-gen-tl-diy-thread-706083/

01tl4tl

are you seafoaming the gas or vac port or both? how much?
a heavy dose of foam thru the gas, 1 can to half tank, will clear injector clogging and piston carbon buildup- which will reduce combustion action and contribute to pinging

TIP before valve adjust, run 1/2 can seafoam in oil and drive 30 minutes or a few days
Gets the area where you will be working cleared of things that can mess up a measurement

change oil and filter with it warm

always adjust our valves with the engine `overnight cold`