1st gen Tacoma accelerator sounds

Tacoma world forum I desperately need help and you guys have helped me every time in the past without fail. I’m praying that someone here is able to give me some help before I take it in to a mechanic

I have done a ton of work on my 96 Tacoma 3.4 automatic transmission with most recently replacing the engine with a remanufactured engine. Since replacing the engine in the summer of last year I noticed a super weird reproducible sound when accelerating between 2000-2500 rpm-3000 rpms. It goes away after 3000 rpms but comes back when the engine automatically shifts gears and the rpms gets back between 2000-2500 rpms. I have been able to kinda reproduce it when in park but it its not as noticeable vs very obvious when driving. I am not getting any warning light or engine codes and no issues when under 75+mph. No obvious misfires on the day to day but did have some sputtering almost stall when I went above 75+ on the highway yesterday. I really think it’s coming from the engine and not the suspension.

As far as the sound it’s super hard to describe. It’s kinda like a static/rice krispy sound. Its a steady sound between when increasing 2000-3000 rpm and doesn’t increase volume, pitch or frequency when accelerating or moving.

I have done a ton of work on each part of the engine with heavy cleaning almost every part of the engine and engine bay but running out of ideas.

Quick recap of things I have done to engine.

Remanufactured Engine replaced in summer 2024 (When engine was replaced I followed Timmy’s video exactly to the T were torque and plenty of lube)
Head Gasket replace x2
Timing belt replacement x2
All Other belts and pulleys replaced
Fuel pump and filter replaced
Replace fuel rail
Deep clean, test of fuel injectors
Replace fuel injector o rings on injectors and fuel rail.
Valve clearance adjustment with all within current recommended spec.
Replacement of spark plugs and wires
Throttle body cleaned including deep clean IACV.
MAF sensor seems to be running normally without issue. Connectors cleaned.
Radiator replaced
Starter replaced
Battery recently replaced.
All vacuum lines replaced
All Fluids frequently checked and within normal levels

So any advice would be super super super helpful. Thank you all ahead of time

 

Honestly man, my first guess would be flexplate, especially since it’s the auto. Definitely check the dumb stuff too though. Could also be a small exhaust leak around the headers, and check the heat shields. Maybe even something like the intake manifold gasket making a weird noise under load. Good luck, you'll find it.

 

When I replaced the engine I had a good look at the flex plate. The teeth were all good not to worn. The bolts I torqued down to proper spec and there is no crack or break in the flex plate. I would think it wouldn’t be the flex plate because I don’t hear the sound when under 2000 rpms, not on start up or when coasting. I will check the heat shields and check for exhaust leaks just super weird it’s only during the acceleration phase

 

love the kid AND the old school torque wrench
Kudos!!

 

Dang
Rice krispy sounds?

If you can consistently replicate sound
Would love to hear in video

will say when I did some major work on old car. Went for ride and horrible sound reverberating throughout the passenger cabin. Sounded like engine was metal on metal. We limped back. Turned out to be a tool left under hood, somehow connected and tapping on fire wall.
Retrieved the tool…..perfect.