Weird Smell in cab/trunk

[svink32]

Hi Guys,

So I have a 2011 Shelby, 11,3xx miles. Purchased the vehicle in July/August 2018 with 8,800 miles on her and drove it 1,200 miles home upon purchase. Had the oil changed at 10,500 miles with synthetic at Ford Dealer about 3 months ago. The car has stock tires and original fluids, she is completely stock (this is all just to give you a background on the car). I drive the car maybe 5-6 times a week for 50-60 miles tops, so she sits quite a bit but not longer than a few days at a time without being driven.

The last two times within the last week I have taken her out, I have smelled this weird smell in the cab. The first time (on Monday) it was after I had driven her about 25 miles, she sat about an hour, and I started her back up and this is when I smelled it. The second time was last night, after I warmed her up and was cruising on the highway I hit it in 4th and brought the RPM's up before shifting into 5th, and I smelled it again. After stopping and checking around, I noticed the smell seemed heaviest in the trunk.

The best comparison I can make is it smells like fireworks after they have been shot off and used. I smelled it faintly under the hood, but I am thinking that's just because it was still in my mind coming from the cab. I checked for any plastic bags that may have gotten caught up under the car, and this morning I checked my garage to see if I have any leaks. Didn't see anything of the sort.

A part of me thinks maybe my speaker wires in my backseat are heating up? I definitely like to listen to my music all the way up...any suggestions or thoughts from anyone with a similar experience?

Thanks guys!!!

 

[98 svt]

Sounds like your cats.

 

[svink32]

Sounds like your cats.

As in the need replaced? Is this something I should be concerned with?

 

[98 svt]

As in the need replaced? Is this something I should be concerned with?

If it is your cats, you will get a CEL for sure. Most people just go with an O/R midpipe.

 

[svink32]

If it is your cats, you will get a CEL for sure. Most people just go with an O/R midpipe.

My first/next mod will be exhaust, although I like the sound of the car stock. I will keep an eye on it!

 

[Catmonkey]

Sounds electrical to me. Can you tell if there are any aftermarket electronics in the trunk for the sound system or a fuel pump booster?

 

[MG0h3]

Sounds like your cats.

My first thought. Fireworks smell of sulfur. Same as plugged cats.

OP you'll usually have a decent bog under heavy throttle.

Sent from my SM-G950U using the svtperformance.com mobile app

 

[svink32]

Sounds electrical to me. Can you tell if there are any aftermarket electronics in the trunk for the sound system or a fuel pump booster?

To my knowledge there is not, however I will get in the trunk and check for both after work today and let you know.

 

[svink32]

My first thought. Fireworks smell of sulfur. Same as plugged cats.

OP you'll usually have a decent bog under heavy throttle.

Sent from my SM-G950U using the svtperformance.com mobile app

I have not noticed anything different under throttle...but this is a new occurrence so I will take note of this moving forward. Is there any other way to determine if it is a plugged cat outside of bogging under throttle or the CEL?

 

[Catmonkey]

If you have exhaust odors leaking into the cabin, you have a bigger problem than smells.

 

[toroweedeater]

does it kinda smell llike a campfire?

 

[Harry08]

Were you really running the car hard? Possible clutch smell?

 

[BlckBox04]

I'm going to +1 on the possibility of it being the clutch. It's more than likely if it was the cats you'd have that smell constantly. And I'm not even sure if cats would even smell, they usually just blow apart in the pipes when they're no good anymore.

 

[svink32]

does it kinda smell llike a campfire?

Not particularly, it honestly smelled exactly like the remains of a fire work after its been shot off. Granted, those smells may be similar.

 

[svink32]

I'm going to +1 on the possibility of it being the clutch. It's more than likely if it was the cats you'd have that smell constantly. And I'm not even sure if cats would even smell, they usually just blow apart in the pipes when they're no good anymore.

I thought about it being my clutch, but to be completely honest I baby this thing...i have stock tires that are fine tread wise but are not extremely sticky, so I only really hit her decently hard in 4th gear so to not spin 'em too bad. After a few minutes the smell goes away. Very odd.

 

[svink32]

Were you really running the car hard? Possible clutch smell?

I have never had a clutch issue, with me driving, in any of the 5-6 manual cars I have had, and I definitely was not running it hard aside from the single 4th gear pull.

 

[svink32]

If you have exhaust odors leaking into the cabin, you have a bigger problem than smells.

I am not convinced it is an exhaust odor...mainly because first thing I did after stepping out of the car was stick my nose in the tips and it didn't smell at all. The lingering smell came primarily from the trunk and lingered there long after the same smell in the cabin went away.

 

[Catmonkey]

It would not be failure of the cats if you don't have the same smell outside of the car near the exhaust tips. Cat failure is internal, not external and would have to come out of the tailpipe. I don't run cats and I have no fuel odor in the car. There are not many places within the cabin or the trunk that outside air will get into unless the windows are down. That leads me to think it's either something in the cabin and/or trunk or something that is getting sucked into the cabin through the a/c/heater air inlets. Then is should be taking in fresh air around the base of the windshield on the passenger side.

However, there are a few grommets that can become dislodged and take in air from under the hood and above the gas tank. There is a large grommet just behind the supercharger on the firewall and an access hole under the bottom of the rear seat on the passenger side.

Since this happened twice, consider it was a smell you passed through that had nothing to do with your car and got sucked into the vents. Was it in or near the same location both times. I know I have followed vehicles that had a really bad gas smell (as in a leak), and it lingered in my car or truck long after that car was no longer in front or anywhere near me.

I'd also get it on a lift and see if anything isn't getting burned by the exhaust pipes. I have heard of the exhaust pipe burning through some of the EVAP related tubing underneath the car.

 

[svink32]

It would not be failure of the cats if you don't have the same smell outside of the car near the exhaust tips. Cat failure is internal, not external and would have to come out of the tailpipe. I don't run cats and I have no fuel odor in the car. There are not many places within the cabin or the trunk that outside air will get into unless the windows are down. That leads me to think it's either something in the cabin and/or trunk or something that is getting sucked into the cabin through the a/c/heater air inlets. Then is should be taking in fresh air around the base of the windshield on the passenger side.

However, there are a few grommets that can become dislodged and take in air from under the hood and above the gas tank. There is a large grommet just behind the supercharger on the firewall and an access hole under the bottom of the rear seat on the passenger side.

Since this happened twice, consider it was a smell you passed through that had nothing to do with your car and got sucked into the vents. Was it in or near the same location both times. I know I have followed vehicles that had a really bad gas smell (as in a leak), and it lingered in my car or truck long after that car was no longer in front or anywhere near me.

I'd also get it on a lift and see if anything isn't getting burned by the exhaust pipes. I have heard of the exhaust pipe burning through some of the EVAP related tubing underneath the car.

Thank you for your detailed response. The first time it happened I considered it may have been since my windows were down and maybe it was something outside. Since it occurred in a different area of town the very next time I took the car out (with the windows down again I may add), I became a bit more paranoid about it.

I am going to keep an eye on it...if I smell it again, I am going to immediately get her up on a lift.

Thanks again!

 

[Catmonkey]

Good luck. If you find out what it is, post it up.