I just purchased a 2015 explorer XLT with the regular 3.5, and immediately noticed this issue. I had the dealer check to see if the work had been done previously to fix this and it has not, so they are going to apply the TSB16-0166.

One thing I don't see mentioned on this thread is that the Procedure 2 part of the TSB states that if the rear bumper removal and sealing doesn't work, they have replacement mufflers that have turned down tips built into them (exiting out of a large hole in the bottom of the tips to not change the styling.) Based on reading some other forums and replies, it seems like that second part does the trick for people if the first part doesn't.

Looking at the way the system is designed, it looks as if the tips are simply too short for the car, and it's allowing the exhaust to be sucked into the cabin that is under pressure through the cabin vents in the rear. Turning down the tips would help a lot of that (or all of it) because it would be directed in a way that shouldn't be able to stream into the car.

I'll post an update when they are done attempting to fix mine, as I'm sure both steps are going to be needed. I get the smell quite a large amount even under moderate acceleration, regardless of HVAC settings or having windows open or closed.

Edit:
One other thing I believe is part of this issue is a simply faulty set of catalytic converters. The more I read on this issue, and the more I experience it inside and outside of the car after having to rev it up higher for various reasons, the more it seems it's simply a heavy smell in general all around the car. I wonder if a simple chance out of converters would help this issue as much as any of the sealing measures they are going to take?

 

Pretty sure what you are actually smelling is from the PTU Leak! Check them out here:

https://www.google.com/search?q=Expl...hrome&ie=UTF-8

PTU Problems | Ford Explorer and Ford Ranger Forums - Serious Explorations

https://ford.oemdtc.com/949/awd-leak...us-lincoln-mks

 

There is more to this than a bit of odor.

https://www.washingtonpost.com/natio...=.6de86ecbcb39

 

data point.
2013 Limited. FWD.. 3.0 V6-N/A...80000 miles, purchased 12-2012. We have had the smell since day one but it only occurs under hard acceleration or up an incline, much like everyone else. Wasn't annoying enough to fight the dealer. I have saved a lot of time doing so from what i have read on these posts...all the trips people take..arguments..test drives..dealerships lies..i dont deal with BS well. .... and still no solution from ford on a model that is now 6 yrs on!

We are in the process of trying to sell our Explorer (not related to the exhaust issue BTW) but my guess we will have a tough time unloading it now and prices have dropped.

My arm chair QB says it is the exhaust tips and related airflow near the back of the Vehicle. Im going to have a look underneath to see if they can be simply extended.

The ironic thing to this is we just bought a bran new Jaguar Fpace...similar exhaust existing from the back, however the tips protrude much farther.

Guess what happens! My wife has burned her knees several times reaching into the back from the longer exhasut tips!

Ya cant win!!

 

I'll save you some hassle, the bad smell is not coming from the rear problems where it isn't sealed right. It's coming from the engine bay and into the fresh air intake. There is either a manifold leak, PTU leak, an EGR leak, or bad converters leaking that are sitting right next to the firewall causing this. I've had the seal and pipe/tip replacement done, and it literally made no difference at all, especially with the rear air on and going up hill. The smell is so bad that it's making the interior stink and I hate to put people in the car to drive around in it.

Another trip to ford is happening right now hoping they start replacing things until it goes away, I feel sick that I bought this used vehicle with 24k miles on it, at a pretty penny, to have only been able to drive it a month while someone figure out what's wrong with it.