Did I just hear my lifters tapping?!

2019 SR DC with the 4.6L w 55k miles

Pulled on to an expressway, heavy acceleration, truck pulled out normally...all except a fast loud tapping while heavy on the pedal. WTF?! Scared me to death. Eased off accelerator and it went away.
So, tried it again, same thing. Tach hits about 4k rpm and the tapping/rattle jumps in.
Home right away, checked oil, it's perfect. Running synthetic at the recommended grade. Just changed it about 800 miles ago and it looks very clean and perfect on upper level.
While parked at house, revved it up and no tapping.
No smoke, no smells, no leaks /dripping underneath, no misfires, no codes at this point... Nothing else other than a very scary rapid tapping under hard acceleration.

Anyone else have this or care to weigh in on the what/how/where?

(If this was one of my RAM 1500 Hemis from a couple years back, I'd know all too well what this meant.)

 

I have experienced something similar to this. I was able to narrow it down to the exhaust on high rpm and under load. I was able to re-create it by getting on the throttle heavy as well.

 

Maybe pinging from bad gas? I’ve never experienced it on my Toyotas before, mainly GM stuff. Could be a possibility though.

 

Thanks. Where in exhaust? Or maybe I should say: What in the exhaust was making such a specific tapping sound under load?

 

Honestly, I'm not entirely sure. I have mine dumped directly after the factory muffler. I backed my truck into the garage and had someone rev the truck and I could hear it coming from the exhaust. I climbed directly under there and it sounds like a harsh rasp at high RPM. I also filled up with premium, just in case it was pinging, which made no difference. I literally only hear it at high rpm or at heavy throttle sometimes.

I’ve read a few other threads about it, because it stressed me out initially as well.

 

I have heard some say that a leaky exhaust manifold can cause this noise. @shifty`

 

So assuming this is a leaky manifold, I'm thinking not that serious to pursue repair if all is working "well enough".

 

Definitely possible. I’d take a look at your manifolds and see if you see any black soot or obvious leak locations. You could also try to tighten the manifold bolts to see if any are loose. It could be a crack in the manifold itself as well.

 

Always hard to diagnose from just a description, but what you described sounds like the classic example of Pre-Ignition/Detonation, especially when it only does it under load. Just my 2c.

 

Ok what the heck mine did this today for the first time. Definitely a detonation type sound. Let off the throttle immediately but hopefully it's not damaged. Is there a bunch of bad fuel out there? I saw there's gas in Florida contaminated with diesel but that's a long ways from the midwest.

 

The last time I heard a pre-detonation type knock was back in the days of my Mother's 77 Buick Electra. Not saying this isn't that but it doesn't sound the same.
For mine, this sound is much more a metallic knock. Exactly like a lifters tap and very much tied to rpms, only at a high Rev under load.
I've read one of the other older threads. A lot fits with the mentioned manifold aspect.
I'll be looking more closely under the hood this wknd. Also hooking up my scanner to Rev it up and watch the oil pressure readings.

Fingers crossed it remains less than any major issue... Need this rig to hold up right now.

 

Mine sounded like someone whacking the side of the block with a hammer really quickly. It was much more pronounced than the typical light ping it can make at 45 mph in 6th gear.

Filled with 93 octane yesterday and it hasn't done it since. Normally I run e85 in the summer but I was trying to get a couple more months out of this oil change. I probably should pull plugs and inspect