2.7L 'slight' ping?

Long story short, I finished replacing the head gasket in my 09 Taco, 184k miles, 2.7 2TRFE. I had coolant slowly dripping into 2 cyls causing misfire on startup until it was cleared. The gasket was also cracked between #3 & 4 (cyl walls & block deck were gently cleaned b4 asm):






I tried to do the job right, the best i could. Head was checked for cracks, cleaned, and surfaced.

While I was in there, I replaced:
-timing chain
-timing chain guides and tensioner
-water pump
-All gaskets and O-rings necessary for reassembly
-plugs
-coils

The truck runs great, doesn't use coolant and has alot more power.....which comes to my issue.

Under acceration load around 2k rpm, I hear a faint sound, almost like a "whispering" or like a slow air leak. It doesn't happen just revving in the driveway. I'm not sure if I'm being too OCD or not, but it WAS doing this before the initial head gasket fail. Now I'm a bit paranoid and wondering if that's what CAUSED the initial failure.

Not wanting to go through this again, if it is indeed pinging, I'd really like to fix it once and for all! I added some lucas sensor safe octane booster to this 1/2 tank of gas and will see if that helps, but it seems like doing so is a mere band-aid.

After this I'm not really sure where to look without shotgunning parts (modern engines are NOT my strong suite!). I'm looking to the following areas next:

-My being overly paranoid?

-can the knock sensor or pigtail be 'degraded' so as to prevent retarding timing without actually throwing a code or light? If so, how would I even test this....just replacing it seems like a chore (intake removal)

-service the intake/TB w/seafoam....potential oil buildup from PCV degrading fuel quality?

-add Moroso pcv catch can to PCV line based on the above (I already have a spare from a different project)

-cooler heat range plugs? (Is this still a thing, or was it mainly on older engines?

-is there some timing/computer related reprogramming that got addressed by Toyota for these engines that I'm missing?

Any thoughts are appreciated. Again, im assuming the truck SHOULD run well on 87.

 

The first place I’d check is the exhaust connection between the header collector and the midpipe/catalytic converters. Mine had an exhaust leak there that wasn’t audible, but my truck would ping very badly under load. I attributed this being caused by the leak before the primary o2 sensor, so it was throwing the AFR readings to the computer askew

 

You know, now that you mention it, this embarrassingly enough is the only area of the project I got lazy on. I didn't have to decouple the header from the pipe to get the head out as there was enough flex. Putting it in was a different story. It was late at night and I didn't replace the exhaust donut gasket....I just bolted it back together. Tomorrow I'll be getting a new gasket. Perhaps, as you said there's a leak that's not enough to be seen/heard but enough to do as you say....either way I shouldn't have been lazy in the first place!

Will see how it goes and post results