"Dice-in-a-cup" rattle help...
 

If I'm driving at a steady speed, in any gear, and give the gas pedal a stab I get a dice-in-a-cup rattle. It does not rattle with a gentle roll-on of the throttle. Seems to be coming from under the car, not engine knock.

Any ideas?

Thanks!

Maybe throttle body chatter?

Something on the floor under the seats rolling around?

Someone put a rock in your cars tailpipe?

A VC put a hand grenade the pin pulled a rubber band holding the handle down, in your gas tank?

(it must be my nap time - :bonk:)

Grenade would have detonated by now, but one small enough to fit in the pipe would rattle around. I'll check under the seats.

What mods do you have?

When I first got my FR-S, one of the first things I did was install puddle lights in each door. While I had the door panels off, I found coins in my driver's side door that would roll back and forth as I accellerated and braked. Removed them and the noises disappeared along with.

When you "stab the pedal" perhaps it is causing the engine/exhaust system to "torque twist" just enough for something to momentarily come into contact with the chassis or a heat shield?

Thanks. Others have had heat-shield rattles, hoping that's it, or something else not serious.

Hey OP, did you end up figuring out what it was? My car has the exact same rattle. 2018 86.


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Still no luck, going to poke around underneath this weekend.

Sounds like it could possibly be a DI seal.

For me it was the front pipe bolt that rattled itself loose gradually. It sounded pretty embarrassing before I finally had it tightened. Could be that. Doesn't exactly match what you're experiencing but apparently this bolt is known for loosening. The sound was coming from directly under the trans tunnel/bulkhead basically

If the car is manual and you're doing it under 3k rpm it could well be knock :iono:

Thanks, taking out the OFT and checking this weekend, at least thats the plan. I just found out I have a broken bone in my foot.:mad0259:

Dude! How hard were you stabbing that gas pedal?!?

I did it while sleeping, even worse. I kcked the wall.

I've had (aftermarket) exhaust rattle under hard acceleration on the rear subframe as well as a 3" hit the front subframe (when I had the Nameless header and JDL 3" over/frontpipe) and the typical Ace hitting the undertray.

Hello everyone, this post is practically ancient history by now but I thought I would update everyone anyway. For me, it ended up being a bad serpentine belt tensioner. My car started doing it super consistently, so I had a friend stab the gas while I watched under the hood.

Saw the belt tensioner rattle and make the noise right in front of my eyes.