y34 - factory exhaust cutout?! No way!!! Dual mode muffler.

[paranoidjack]

So the other day I was trying to chase down the source of this nasty rattle from under my car. I was sure it was an exhaust shield.

it wasn't.

Turns out at full throttle, my car starts to sound really nasty...it's like once I move enough exhaust, it changes the car...starts to feel faster...sound meaner....and starts to rattle like hell!!?!

So I get under the car and am shocked to see an exhaust cutout valve! I looked in the FSM and Infiniti refers to it as a dual mode muffler, with a control unit in the back. It is supposed to open up at certain rpms's under certain loads and sound badass and move gases. Really cool. When it is open (despite the tin can knocking), it sounds MEAN...mean...love it.

However, I need to fix the horrible rattling. I assume something inside is no good, maybe the butterfly plate is swiging around? I also assume it is gunked up because I have to bring it to WOT a few times to "pop" it open, and then it seems to behave normally.

Why can't I find ANYONE on these forums talking about it? Do the other M's not have it, is it just the y34? Man it is great, sounds great, if I can get it working the way it should.

Anyone have any insight on if it can be removed and serviced?

Here's a snippet from the FSM that talks about it. Thanks!

[Ilya]

Very neat hah

[EniGmA1987]

First Ive heard of it being on the car from the factory. Pretty cool really.

[paranoidjack]

So I cut it out and put a pipe in.

All is the same!!! I still have the rattling and still hear it "open up" if I push it hard. Maybe something loose inside the muffler, there are no loose heat shields, and the mean sound is married to the rattling...will have it replaced and report back on if the sound is gone. But I have the exhaust control valve, and asked that it be removed so it could be reinstalled if necessary.

[EdBwoy]

I ran into a situation that might or might not be similar with regards to rattling. Check your first set of mufflers.

My pass side "pre-muffler" seems to have collected a lot of water and is corroded. This sent a good amount of muffler material into the right pipe with the butterfly valve. Intuitively it makes sense: The right side pipe isn't usually open so it doesn't let all the exhaust gases through while the left one does. However, water vapor is constantly being produced as a result of combustion so it settles and cools in that pre-muffler feeding the butterfly. Give it time and stuff starts corroding.
That's my theory and I'm sticking to it! So, kids, the moral of the theory is - please keep those RPMs in your y34s high; or if you never drive it hard enough to trigger the dual exhaust mode, make it a single exhaust.

I have pictures of my exhaust work that I will work on uploading later.

[Double E]

We did talk about it here years ago. Most of us just wired it open permanently and/or put on a remote exhaust cutout before the mufflers.

topic389633.html?hilit=butterfly

topic508684.html?hilit=weld

[MinnesotaM45]

Your resonator is causing the rattling and it will probably leak if not already. I did a resonator delete and installed a Magnaflow dual tip muffler. Sounds sweet now.

[BlackCat81]

You probably have a broken baffle in the muffler. It's also not an exhaust cutout, those are either electronic or manually opened devices that completely bypass the muffler. Dual mode mufflers have been around for a while, Chevy has used them as an option on the corvette since 06'ish I believe. I also worked on a 13' Maserati Grandaturino PinaFarino at work that had it as well. You don't know heaven to your ears until you hear a Ferrari built 4.7 V8 bounce off the rev limiter with the exhaust valves open. Haha