Have a 2010 outlander with V6 @ 186xxxkm, noticed a smell like burnt gun powder as it idled warm. Son complained of it when I opened the hatch, car runs slightly rougher than I recall months before and on cold start the idle wavers up and down a bit now. Previous owner kept it well and it has no codes, just wondering if I should check a sensor or something to be sure. I grew up on carburetors so I'm not much good at this, don't want to plug a cat cause it looks like an awful job. It's probably due for plugs and the air filter was clean when checked 5k ago, far as my knowledge goes.
Sorry if this is a dead horse topic, I did a quick search but didn't come across this. Thanks in advance for help!

 

Coincidentally mine was gassing me up to a week ago, Brought to my garage and they welded a small cat leak for $30. There's also a donut/joint ahead of the cat, engine side,(You can hear a spitting on accel.) that needs to be replaced that leaks but I didn't have the donut at that time.Smell down 95% since. A bad sensor (02 , oxygen sensor) will turn on your check engine light. Code usually in the range of PO410-440. If it comes to the crunch you can buy aftermarket downpipe and cat for $150 from eBay. which beats $800 from Mitsu. Black tape on check light works good also

 

Haha yea I had jeeps growing up, I tend to tape, but we've had awful luck with family cars so I want to get ahead of it. I'll go bookmark an eBay pipe set, but the smell is only from the tailpipe so far. Haven't noticed any signs of a leak, just wavering cold idle and runs a bit less smooth. I will YouTube IAC and MAF and whatever ones are easy to check/clean when home but if I'm missing something obvious now's a good time for a laugh!
Does overfueling or exhaust restriction throw codes?