black smoke out of tail pipes everytime i start it
 

my monte carlo blows black smoke out of tail pipes everytime i start it and sometimes while driving and i smell it inside the car when i turn it off. and keep in mind i just bought it so when i floor it to see what its got it cuts out like maybe it needs a tune up but my mechanic said it doesn't. It also shakes back and forth while im at stop lights sometimes. PLEASE HELP!

Hello and Welcome to the forum! :thumbsup:

Tell us a bit more about your car type, year, engine size etc. Lets see if we can get this figured out.

Check all vac hoses, fpr, and injectors.

Certainly sounds like its running too rich on fuel.

Its a 2001 monte carloo ss 3.8L v6. What's fpr? And what does it mean to be running too rich on fuel?

Means the engine is injecting to much fuel, likely one of the sensors is not working properly. Do you have a check engine light on?

It could be a Bad O2 sensor but then again you would have a check engine light on... Is it on?
If it is...Take it to your local auto parts and have them run scan.. (Its free) That should give you a good idea whats wrong with it.
It will give you a code ... that will indicate what the problem is.

But with all that black smoke..it will eventually clog the Catalytic converter which will be a whole other issue.
So, I recommend you get it resolved as soon as possible...

Fpr=fuel pressure regulator

If it's black smoke you may have leaky injectors.

If you're mistaking blue smoke for black it's probably worn valve stem seals and/or worn valve guides.

Yes the check engine light is on and what are valve stem seals and guides?

Welcome to MCF!
]How much do you know about cars? I only ask so that any of us who can help, can explain our thoughts in a way you will understand.
Is If the smoke is blue then you have a fuel delivery problem, bad or stuck open injector. If the smoke is black then it could be a one of several things. Since you do have the CEL, Check Engine Light, the first thing you should do is get that read. It could lead you right time the cause of the problem!

I don't know much about cars but you guys are being a lot of help...what about it bucking at the stop lights

I'd suggest you take it to a trusted garage and have it looked at. They'll be able to read the check engine light code and go from there.

If you can, have the PCM queried to find out what code set the CEL.

The intake and exhaust valves move up and down in the cylinder head to allow the fuel mixture into the cylinder and the spent charge out of the cylinder. there are guides the valves move up and down in. Over time the guides can wear creating excessive clearance. The valve then rocks side to side in the guide. The stem seal is located in the head on top of the guide bosses. When the valves rock side to side it elongates the seal and oil can be drawn into the combustion chamber. When the engine sits the oil accumulates in the cylinders so when you first start the car blue smoke comes out the tailpipe.

If you have black smoke coming out the tailpipe it indicates a rich (too much fuel) condition. It's possible the fpr could be malfunctioning and allowing fuel to get to the injectors while the car is off, but it is rare for it to produce enough pressure to unseat an injector. That's why I'm leaning towards a leaky injector, but that code will really help in pinpointing the problem.

If oil or coolant, in your case oil is more likely, it could cause your engine to stutter. But That's a big If. Right now with what we know, your best bet is to get that check engine light Read and take it from there.