Symptoms: i have a burnt/chemical smell only around both rear rims, black soot and wet drips on the exhaust/garage floor, and a high-pitch metallic hiss/whistle only when accelerating between ~1.5–3k RPM, with no noise when revving in park and the issue getting louder over time.



Issue: This combination points to a rear exhaust leak before the tips, most likely at a stock rear joint/clamp or a small crack at a factory weld, causing exhaust gases to escape under load and get pushed into the rear wheel wells.

please help me what the problem is… I started to smell burnt smell on both of mg rear rims area today. I keep hearing high pitched hissing sound during 1.5-3k rpm acceleration ONLY. I know a lot of people say don’t worry that black soot is completely normal but there is definitely something wrong with my car. The black stain is significantly larger amount than others and I smell burnt plastic smell and the sound during the acceleration

 

Nobody cant say whats wrong just by forum writing. Please take the car your local garage for quick checkout.

 

If you have been driving your F on salt-covered roads, THAT could be what smells as it warms, then 'bakes off'.

The black soot comes from the built-in 'drain outlets' at the joints under the rear axle area. You will get more condensation in cold weather.

Can't help with the noise. Sorry.

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It is great that you are aware of the behavior of your F. For peace of mind, bring it to a local garage (doesn't need to be a Marque specialist) so that the underneath can be checked. Your profile states that you are in CA...is that CAnada or CAlifornia??

Take some pics of the undercarriage and share those, along with the suggestions of the shop.

 

It'd help if you told us where the sound seems to be coming from. There'd be a world of difference between, say, a rear wheel bearing and something under the hood.