Strong exhaust smell

[Lippy]

My 325i has a strong exhaust smell. I'm not sure if its unburned fuel and possibly its running too rich or something else.
When I bought the car in the Spring I did a whole bunch of maintenance / repairs. I replaced the: Plugs, wires, cap, rotor, injectors, coolant temp sensors, and O2 sensor. I cleaned the MAF and the throttle body and had a shop replace the injectors (one of them was bad).

The car seems to idle correctly and doesn't sputter, but the exhaust is nasty.
Any thoughts?

[Vincenze]

You should replace the exhaust gaskets:
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11761711717

[Lippy]

The smell isn't in the car so much, but just in general the exhaust stinks.

[tomstin]

A few thoughts. If the o2 sensor is bad it could cause the engine to run rich. Also, if the cat is going bad they can cause some bad odors. Pull the spark plugs and make sure they are not fouled.

Another thought, if the car has been sitting, any sign of critters?

[Lippy]

I replaced the o2 sensor, so I don't think that's it. The car sits some (especially now that its winter) but it's in a garage, so critters are possible, but not likely.
I guess it could be a bad Cat. I'm not sure how I would test that or if I would fix anyway due to price. I went with Vintage PA plates so I'm emissions exempt.

[Lippy]

The fuel pressure regulator looks fairly new, but I thought about replacing it anyway to see if that helped.

[zaq123]

Does it smell like a race car or a motorcycle (unburned fuel and no cat) or it smells like some burned oil?