Burning smell from air vents + occasional puff of smoke from engine

[arfai22]

Hey guys,

I noticed that when my ST is up to temp and idling with the heater on, I will occasionally smell a horrid burning smell from the air vents and a puff of smoke? or steam? will appear from the engine compartment on the driver side. The smell is so bad and overpowering I have to roll all of the windows down, it irritates my nose and throat too. Has more of an almost burning electrical smell, definitely not coolant. When I start to drive again, the smell and smoke disappears... it only starts to happen when I'm stopped and idling. It has happened three times now, so it's an intermittent issue and doesn't happen all the time. Doesn't indicate that it's overheating either. I've taken it into the dealer two times now and they are saying they can't find any leaks or issues but this is clearly not normal. Anyone else experience this?

 

[SOUTHFLST]

Does it smell like rotten eggs?

 

[arfai22]

It doesn’t. However, at times I have noticed the rotten egg smell after heavy acceleration but I just figured it was off gassing the new cats. Took it in to the dealer for that too just to be safe and they said the catalytic converters were fine.

 

[SOUTHFLST]

Could be your flex pipe. Any exhaust rattle or ticking sound?

 

[Cruising68]

The rotten egg smell suggests a leak pre-cat IMO. But then again new cars can give off strange smells when everything is initially burned off the exhaust. Good luck finding the issue.

 

[TMac]

My first thought like everyone else would be a slight crack in the cat. But this should be accompanied with some odd noise. Second would be a possible coolant issue, but since you insist it's not coolant, I'd suspect a wiring harness or loom is misrouted; potentially contacting a hot surface.

 

[JohnE]

Rotten egg smell is post cat. My thought is a cracked weld at the exit side of one of the cats like we’re hearing about which causes excessive flex pipe rattling.

 

[arfai22]

Took it to the dealer again today while it was acting up and they were finally able to witness the issue. Just from looking at it they had no idea where the smoke and smell was coming from in the engine compartment, but could visibly see and smell what was going on. Looks like not going it have it for a while, unfortunately I'll update once they're able to figure out what's going on.

 

[Cruising68]

Took it to the dealer again today while it was acting up and they were finally able to witness the issue. Just from looking at it they had no idea where the smoke and smell was coming from in the engine compartment, but could visibly see and smell what was going on. Looks like not going it have it for a while, unfortunately I'll update once they're able to figure out what's going on.

Good news that they actually saw it. My favorite dealer response is "problem not found" or "could not duplicate". At least now they should eventually figure it out.

Good Luck!