What does it mean when your car exhaust starts to get more noxious than usual?

poor muffler?

is it pumping out more smoke or does it just smell bad, worse than normal?

if it just smells it could be a plethora of reasons ranging from dirt or rust on your pistons to a hole in your muffler, you’d need to get it checked out, and the sooner the better usually.

It may be a problem with your catalytic converter.

It smells near lethal (like it did last time). No funny sounds. Slight loss of hp, I think, and maybe a minor (10% or less) drop in gas mileage. No smoke.

Smells lethal? That sounds serious. My best advice would be not to stick your nose down there. Then maybe take it to a body shop.

Have you tried giving the car a tune-up? Also check the timing and depending on the year of the vehicle check the vacuum hoses. If it has a computer “brain” it could be that.

Sounds like it might be a faulty O2 sensor. It’s supposed to monitor how complete the combustion of fuel is so the computer can adjust the air/fuel ratio. If it goes wonky, the fuel may not be burning completely, which would cause the exhaust to smell of the products of incomplete combustion and cause a loss of power.

In addition to @Harp‘s response I want to add to have your exhaust checked for leaks. A leak can decrease horsepower and also make fumes seem more noxious. It goes without saying that it can also cause serious illness or worse if the leak is invading the car interior.

Go to Auto Zone and get your OBD II trouble codes read, presuming the car was built after 1996. Based on your symptoms, I’d say your problem is A/F ratio; the engine is running too rich. O2 sensor, like Harp says, or MAF sensor, or IAT sensor reading the air temp colder than it actually is. The IAT sensor is fragile and easily dislodged on most cars. Had anything done under the hood recently?

I heard it has something to do with your muffler. Someone told me it was the ‘catalytic converter’ and I know I probably spelled that wrong! I had a ‘87 Cheverolet Monte Carlo. It had the rotten egg smell and a man told me this one day in a parking lot of Advance Auto Parts.

@peyton_farquhar taking it to a body shop is like going to a heart surgeon to get a haircut. He needs to take it to a mechanic. A body shop does body work, i.e. paint, fenders, etc. A mechanic works on the engine, drive train, exhaust, etc.

@evelyns_pet_zebra you’re right, I meant mechanic. My mistake.

@peyton_farquhar no harm =)

@ShanEnri, you spelled it right and you got it right, at least so far as that car was concerned. Montes of that generation all had the rotten egg problem, even when they were brand new.

Cats sometimes foul up and start choking off the exhaust. Back when you could still buy leaded gas, it was a common problem. These days, it should not happen unless you’re clueless enough to drive around with your Check Engine light on for 20,000 miles.