Rattle behind right seat

[playswfire]

I have noted a rattle behind the right seat when decelerating up to a light.

It is unaffected by braking. It occours when I am coming to a light speed < 20MPH. It sounds like a heat shield directly behind the passenger seat (I looked at the panels behind the seat, and they appear secure)

I looked in the engine bay and could find nothing even slightly loose.

Has anyone else had a similar issue?

I recently found a missing bolt underneath when doing O2 sensors, thought that was it, but no change.

 

[nsxtasy]

There's a lot of stuff behind the padded panels behind the seat, including the ECU and various relays and stuff. It's pretty easy to work the top bolster loose and then the side, to take a look at everything.

 

[EdinKali]

The sound may also be coming from the engine compartment. I had a rattle that I thought was coming from behind the passenger seat and it turned out to be the alternator pivot bolt not being fully tight. The rattle only happened when the engine was cold but would disappear when warm(when the metal expanded). It was likely snugged up when the engine was warm and then when it cooled down there was just enough clearance to cause a vibration/rattle. When I changed the alternator belt I discovered the pivot bolt wasn't fully tight. Noise has not returned since I changed the belt and tightened the bolt correctly.

 

[greenberet]

Has anyone else had a similar issue?

Yes.

One rattle was particularly hard to find. One of the three bolts that secure the a/c belt tensioner mechanism to the engine block (location: behind the right seat) on my NSX had been overtightened by a sloppy mechanic. The threads had stripped and one of the bolts could no longer be properly tightened. It was loose and rattled against the tensioner pulley - sometimes. I looked for that rattle for years before finding it by chance.

Another nice location for a rattle is if something falls down the cabin ventilation duct, which is the hollow space inside the B-pillar. That goes from the seat belt straight down to a one-way flap behind the side sill. If you remove the side sill, you can easily take a look there.

Another possibility is the cover of the engine management computer. Since that’s easy to get to, it’s not much of a challenge, though.:smile:

And unfortunately, I'm sure there are a thousand other possibilities.

 

[Tom239]

The lid on the ECU (interior, behind panels behind the seats) rattled on mine,
easily fixed with rubber tape.

 

[playswfire]

Thanks for all of the feedback, I will be digging in to it this weekend.
I did fiund a heat shield in front of the engine that sems to have the correct tone when popped. I will tighten that up when I get my next timing belt!