Hi.
I could really use some help with an exhaust issue on my 2014 Infiniti Q60s coupe, 55k miles, automatic.

This winter, I noticed smoke only coming out of one muffler. When I'm in park or at a stop sign/red light, the car gets very bassy and produces a minor vibration.
I thought exhaust leak, but 2 exhaust shops confirmed there was no leak and they could not confirm what the problem is. no rattling noises when they banged on the exhaust/cat and no lights on the dashboard, no rotten egg smell either.

Please share some expertise, I'm not sure how to proceed.

 

You have only one muffler. It has two exits. You’re saying condensation/exhaust flow out of only one exit?

 

I didn't think anyone still had the stock muffler!
its known to fail internally. Time to go aftermarket.
Lots of options available from stockish quiet, all the way to obnoxiously loud.

And as stated above, what??
What kind of smoke? And exactly when?
Describe color and smell

 

Thanks for the reply but to clarify, 2 new aftermarket axle-back mufflers were installed.
There is a new issue with a clog on the drivers side, on the mid-pipe, just before the stock resonator.
No weird smells, regular exhaust color out the working passenger side. From the clogged drivers side, there is barely any exhaust and by touch you can feel it is cooler compared to very hot on the passenger side. This is how i determined the clog was just before the stock resonator. by touch.
Also I stuck a plumbers snake up through the muffler and on the problematic drivers side i was unable to get past the resonator, and on the working passenger side, I could go well beyond the resonator..

I assume I'll have to drop the mid-pipe to inspect further, perhaps the baffling in the resonator broke loose and caused a clog.
Those exhaust bolts are extremely corroded from winter/salt so it's not good. Maybe I'll get lucky and be able to cut and replace the resonator, but not sure why that Y pipe a few inches before the resonator was cooler than the passenger side. Cats and Y-Pipe by the engine seem fine, no rattling, smells or obd2 codes (bludriver reader).

 

No real advice here as short of dropping the piping and inspecting everything from the cats back we could only guess what the issue is. I'd be more inclined to believe that a chunk of the ceramic honeycomb inside the catalytic converter broke off and is "stuck" somewhere downstream causing a obstruction. This material is known to deteriorate. While it is possible that some of the baffling inside the resonator failed that would be a rare occurrence. Again, you will have to drop the X-pipe and "see what you can see." If you have or can find someone with a borescope that would be ideal.

However, to note: from the assembly line the Coupe only came with one muffler (can)- 2 pipes in/ 2 pipes out. Period. Only the sedan has 2 separate cans. Unless there has been some jerry-rigging involved or your exhaust is aftermarket and NOT OEM, this is fact.

 

Thanks for the info.
I agree with what you wrote about the stock setup.. There was 1 muffler with 2 pipes in and out. I've since removed that stock muffler and installed 2 separate Axleback mufflers. If you mean the resonators, there are 2 are on the mid-pipe.

 

So not OEM. Got it. That clairifes things somewhat...

Your issue is upstream. Resonator or cats. No option but to drop the X pipe and go from there.

Also, don't assume the left (driver-side) is the culprit. With the X pipe all exhaust gases get mixed so the right-side could be contributory. Unless that was monkeyed with
¯\_(ツ)_/¯

Let us know how you make out.