[RxSummit16]

So...started up my car yesterday morning and backed out of garage and there was this loud metal on metal rattle. So I take it to dealer and they said the "flex joint" in the exhaust system was moving around a lot so they readjusted it (which has seemed to stop it for now). Exactly where is this in the exhaust system? Got a quote to have it replaced for only $100 from a muffler shop but that seems really cheap. I have about 48K on the car and for a while now at times I've heard a very light "musical" rattle at low speeds at certain times but this was a lot louder and harsher but seemed to come from same area.

[cellsafemode]

flex joints are the little bulbous areas near the secondary cats (they look kinda like short flat cylinders around the exhaust pipe)

I'd be very suspicious that this is the resonator (your "x" pipe) that exists before the muffler. There is a drain hole there that often has a weld break. This will cause a horrendous metal on metal tin can kind of vibration at various throttles (usually not while idling and hard to recreate in neutral).

The only solution to that is hoping it's near the external part of the drain plug and re-weld or cut that stupid thing off and replace it (either with a stock resonator or a real x-pipe).

it's a bit misleading to use your ears to kinda get a feeling of where it is. The metal tinging sound travels the entire exhaust system and if it's the resonator, it can sound like it's coming from right by the drivers door but it's not. The only way to know for sure is to put it up on ramps, have someone throttle all over the place until the sound is produced and then take a screw driver and put it in the drain hole and see if it stops instantly. If it does, you found your problem. If it doesn't, then perhaps you have something else loose. The exhaust shields can possibly become loose over time and they're as thin as a tin can and can easily vibrate.

[RxSummit16]

Thanks...I saw your post on the other thread about this but wasn't sure what part the tech was talking about in reference to the flex joint. Mine only really occurs at low rpms mainly in gear. If it returns, I'll probably have them replaced and go ahead and get a high quality real x-pipe at the same time. The only exhaust mod I currently have is the flowmaster axleback. Just happy it doesnt seem to be an overly expensive issue.

[cellsafemode]

the rpm it occurs at will depend on the particular frequency your exhaust produces and the extent and place of the weld break (assuming it's the resonator like seems to be common).

it'll be pretty apparent it is that though. Tightening up the exhaust would only potentially change when or how loud it gets, not if it makes noise. if it's fully gone now across your rpm band, then it's probably not what i'm talking about.

[RxSummit16]

So finally got around to installing x-pipe and new flex joint to try to remedy the rattle. Didn't help. At this point I'm 90% convinced its a piece of heat shielding that is loose somewhere near the front of the car. The problem is, you can only hear it in gear and slight acceleration. Any ideas other than just getting under it and using trial and error? Any other thing it could be?

[cellsafemode]

I found some big underbody panels with some loose bolts that I tightened up before getting the x-pipe, and there is thin tinny metal shielding around the cats that can be very close to the body in places.

I dynomatted the other side of these metal shields all around the secondary cats just in case.

First step would be to just get under there and check all the bolts you can reach to see if any are loose. I wouldn't get into the whole dynomatting anything until that step is done first. Though it's also pretty possible that the frequency your exhaust is hitting just resonates a shield even if it's not hitting the body or anything ....in which case the only solution there is dynomat or a new exhaust. I wouldn't just leave the shielding off.

[RxSummit16]

Yeah, I think its going to be a pain to nail down. Funny thing is, the flex joint definitely was rattling too, just not what I'm hearing.

[RCF]

Ever figure this out? Mine is going in Friday for this among other things. Sounds like the shield on the drivers side exhaust manifold to me. Can tap it with something and recreate a “tinny” sound that I don’t get on the passenger side.

[cellsafemode]

I fixed mine by replacing the resonated x pipe. Put a regular x pipe on.

The resonator has a weld that cracks internally.

[calebglenn]

Originally Posted by RCF

Ever figure this out? Mine is going in Friday for this among other things. Sounds like the shield on the drivers side exhaust manifold to me. Can tap it with something and recreate a “tinny” sound that I don’t get on the passenger side.

Took mine into the dealer (under warranty) and at first they told me nothing was wrong (which was bs). Literally pulled out of the lot and the noise came back so I turned around and had the mechanic come look at it. He used a long stick to press on this spring looking mechanism near the muffler (not sure if this is the flex joint people were talking about) and the noise stopped.
Long story short they replaced the whole exhaust system and said apparently my muffler was ‘cracked’ but hey it was free and I don’t hear the noise anymore

[cellsafemode]

that spring is the afm valve.

Though, the sound probably stopped just from putting pressure on the system in that direction. The spring controlled valve itself is not something that tends to rattle.

A cracked resonator / muffler is likely in that a weld probably cracked. (Mine was in the resonator)

[calebglenn]

Originally Posted by cellsafemode

that spring is the afm valve.

Though, the sound probably stopped just from putting pressure on the system in that direction. The spring controlled valve itself is not something that tends to rattle.

A cracked resonator / muffler is likely in that a weld probably cracked. (Mine was in the resonator)

Ahhh thanks for enlightening me. I did just look at my quote from the dealer and it did say ‘cracked muffler’. I was confused when I initially saw that so thanks for the clarification!

[DIYguy]

FWIW, on mine the AFM "valves" (the things in the photo) were rattling like mad.
They would resonate at certain rpm's and engine loads and could be quite loud at times.
I wired them completely open using some thick steel wire and then put stainless steel hose clamps across the square tops and around the pipes, forcing their shafts into the pipes tightly.
If I ever have the exhaust system off the car they will be welded in an open position permanently or just removed.

After doing that, the exhaust rattles disappeared and have not returned.

Based upon posts on this forum I did poke around the x-pipe on mine but could find nothing wrong.
However given how many people have had problems with them that is very a good place to look (and I am keeping an eye on mine).

[cellsafemode]

interesting ... the springs on the afm valves should basically eliminate rattling but i guess tolerance variation will lead to contact between the valves and pipe.

My suggestion would be to just get a good axle back exhaust. Almost all of them result in you cutting the pipe before the valves (removing the valves) .... removing the variable.

It does make v4 mode audibly noticeable not having the valves...but you're only ever in v4 mode when cruising and not trying to impress anyone anyway.. or pick one of the various options of tuning it out / making it toggle-able if it bothers you.