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Discussion Starter #1
I have been experiencing a fantastically annoying buzz from my exhaust since I received my 2012 S in May. The cause is the valve in the exhaust that opens when Sport mode is activated. When malfunctioning, it buzzes like an angry rattle snake at low RPMs before the vacuum pressure builds, especially on start up. There is a known problem with the vacuum source that actuates the valve. Lotus has no idea how to fix this yet, but is aware of it. With all the other problems Lotus is having, I suspect this one will fall down the priority list. I am actually trying to figure out if there is a way to manually "prop" the valve open regardless of whether or not Sport mode is activated, bypassing the vacuum feed until the problem is resolved.

BTW - I posted this as a reply to another thread, but wanted to post it as a separate thread so people are aware of the issue.
 

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Sorry, no suggestion on a fix, but I have been wondering if Evora owners don't just leave their cars in Sport Mode all the time anyway?
 

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Discussion Starter #3
It happens regardless of whether or not S mode is engaged. The valve doesn't seem to fully close or open. My guess is that it's a dual chamber set up and that the vacuum is shifted between chambers, which would explain why it could be vacuum related and present in both Sport and Normal mode - i.e., the valve needs vacuum whether it is open or closed.
 

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Unless Lotus has changed the valve in 2012 it is definitively not a dual chamber.

In fact you can just disconnect the vacuum hose (remember to plug it when you do). Access is in the back on the right behind the panel on the muffler. The engine muffler will then remain open, i.e. in Sport Mode. Takes about 5 minutes.

Even if you don't want to keep it like that you might at least want to try it to isolate the source of the buzz.
 

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BTW - I posted this as a reply to another thread, but wanted to post it as a separate thread so people are aware of the issue.
Thanks for added insight. Yes this deserves its own thread. What is weird about my buzz, is that I did not have it (or at least I did not notice) for the first some 1200 miles.
 

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Sorry, no suggestion on a fix, but I have been wondering if Evora owners don't just leave their cars in Sport Mode all the time anyway?
Cannot leave in Sport mode, it resets and even the other post regarding disconnecting vacuum while this would leave exhaust in Sport mode, would not adjust traction control without the switch reengaged.
 

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Discussion Starter #7 (Edited)
Unless Lotus has changed the valve in 2012 it is definitively not a dual chamber.

In fact you can just disconnect the vacuum hose (remember to plug it when you do). Access is in the back on the right behind the panel on the muffler. The engine muffler will then remain open, i.e. in Sport Mode. Takes about 5 minutes.

Even if you don't want to keep it like that you might at least want to try it to isolate the source of the buzz.
Very helpful. Do you know where the vacuum hose originates in the engine bay? If accessable, plugging it at its source of origin seems like it would be easier than dropping the panel and removing the hose at the valve.
 

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My car is in shop for muffler replacement under warranty.
 

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Discussion Starter #9 (Edited)
Interesting. They said this problem was not the valve, but the vacuum source. Frustrating. I will push on my end with the dealer. In the meantime, I simply plugged the vacuum line in the engine bay. There is a three way valve located adjacent to the air box. The lines are orange-ish. One line goes to the exhaust and the other seems to open a valve in the air intake passage that feeds the air box (perhaps for increased sound or more air flow). So, I can still use the Sport mode and it functions in all respects except with the exhaust, which is now always open -- no buzz. I actuallly prefer it this way.
 

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Interesting, and no error codes? So many tuners claim they can not bypass the error code if an aftermarket muffler is installed on the MY12's. So simple to just plug the line

I did not ask for a muffler replacement, just told dealer I had a buzzing sound
 

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Discussion Starter #11
Interesting, and no error codes? So many tuners claim they can not bypass the error code if an aftermarket muffler is installed on the MY12's. So simple to just plug the line

I did not ask for a muffler replacement, just told dealer I had a buzzing sound
No error code. Plugging the line is really no different than having it hooked up to the exhaust valve. All you are doing by plugging the line at the point of origin is changing the termination point of the vacuum line, in effect shortening it. Problems occur when a vacuum line is left open or leaking, which is the opposite of plugging it. Luckily, the natural state for the valve is open, rather than closed. So, win/win.
 

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Hello,
since I got my MY12 in July there was a"snazz" coming from the exhaust too - it was not that annoying so maybe not quite the same extent (I never got an error code on this too)
I recognizedthat the exhaust note gets better (and also less "snazz") when you ´ve driven some more miles with the car - so I´ve driven ca. 3300 km up to now and all is better..... (on TLF there is a swiss Evora driver that had reported the same problem but I do not remember if his problem is solved now)
 

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Just so i'm 100% sure before i start futzing around in the engine bay, in the attached pic, is the vacuum line to disconnect the one that snakes to the bottom right in the picture (it snakes all the way down to underneath the engine)? And then you leave the other 2 lines untouched I assume.

Also, what did you guys use to actually plug the now-empty third port on the 3-way vacuum hub? Is there a particular diameter rubber stopper of some sort that i can pick up from Home Depot?

And finally, what did you do with the now-dangling exhaust vacuum line? Did you just use the extra slack to loop it around the vacuum hub and tie it off in a loose knot?

Thx in advance...
 

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It's better to remove the line at the other end where it connects to the exhaust.
 

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I think we put a fitting bolt in the hose end and used a tyrap to secure it.
 

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thx for the info. Ended up finding vacuum plugs at O'Reilly's that i used to just cap the 3rd prong of the plastic "vacuum hub". Rather than disconnect the line on the exhaust end of the line, i disconnected it by the air box and ziptied it folded back on itself to the 3-way plastic hub so there is a quasi-seal.

An unexpected and very welcome benefit is that the exhaust seems noticeably louder all around, and even pops and burbles sometimes when revving the engine and letting the RPMs drop back to idle (this never happened with the vac line connected in stock configuration). This may delay my Larini purchase bc the stock exhaust definitely sounds better (although still not as aggressive as I would probably like).
 

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Just to add to the info. I "melted" the vacuum hose about a month ago and just removed it. I did not notice any effect on the performance with the hose loose. Just replaced it on Friday and the valve change with sport mode works fine now, but I didn't notice any difference other than the obvious that the valve didn't open when I hit the sport button. I have the Larini without the 3rd resonator on a 2012 S. There are apparently differences for sure in the model year cars. Shinoo at Sector 111 has the NA 2010 with a Larini as his test car and no 3rd resonator and the sound is no where near as good as my 2012 S with the Larini. This thing sounds "properly exotic" vs just nice with the stock setup. They of course removed the 3rd resonator on later MY12 cars and now on 13's as well so it certainly isn't necessary, but who knows what other changes they may have made to accomodate this. No opinion here, just adding my experience to date.
 

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Discussion Starter #20
thx for the info. Ended up finding vacuum plugs at O'Reilly's that i used to just cap the 3rd prong of the plastic "vacuum hub". Rather than disconnect the line on the exhaust end of the line, i disconnected it by the air box and ziptied it folded back on itself to the 3-way plastic hub so there is a quasi-seal.

An unexpected and very welcome benefit is that the exhaust seems noticeably louder all around, and even pops and burbles sometimes when revving the engine and letting the RPMs drop back to idle (this never happened with the vac line connected in stock configuration). This may delay my Larini purchase bc the stock exhaust definitely sounds better (although still not as aggressive as I would probably like).
I had a relatively simply fix, though some will criticize it as at risk for failure. I simply threaded a fine thread screw into the valve fitting that was open to seal it, then fitted the hose over the other end and almost back onto the valve fitting. So, mine looks like the line is connected, but is effectively "spliced/plugged" by the screw that is now within line. I would clearly never do this if the line was the source of vacuum, but there is no way for the screw to be sucked in through the valve fitting and the hose fit perfectly/securely over the screw head. No issues at all on my end.
 
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