Hey all you nissan guys....I'm having some issues with my 97 altima. Recently it started sputtering, idling really erratic, dying out and blowing out black smoke. It's been to the mechanic alot lately and even they can't seem to find out what it is. It has had the plugs replaced, distributor cap and rotor replaced, new sensors(crank and knock) and the checked the maf sensor and idle motor. Does anyone know what could be wrong with my car? Could it be the cold weather or something cuz its really cold in South Dakota.

Well if it was the cold weather it would run better on hotter days right so.....did it run better on hotter days? You should check your fuel filter it could be clogged or even if your cat converter is clogged it could also cause those probs. Also check all vacuum line to see if they are leaking.This is all i can help you with unless you tell me more about the problem in detail. Good Luck!

Another thing it could be i didn't think of is your Tps(throttle positioning Sensor)

Yeah they checked the fuel filter and the fuel pressure and it's all good. I added fuel injector cleaner and fuel treatment. Ran good for a few days and started acting up again. Today was a nice warm day and it still is acting up so I know now that it ain't the weather. When it acts up it smells like oil and gas too. On a cold day it runs good for few minutes while it's warming up and then the idle speed drops like its about to die out and it races to about 2000rpms. Then the idle drops and it dies out and when i start it back it putts and sputters and blows black smoke.On a warm day it runs good, but after we drive it a few times it sputters and dies out and it starts right up again. When its parked and running the tachometer needle keeps quivering. If I give it a quick rev up it settles below to 1000rpm mark. Then if I shut off the engine and start it again it runs funny again. That's basically what its doing. I was told it could be worn camshafts or timing chain but I dont know. The motor has more than 232000 miles on it so who knows
Modified by ivorton23 at 4:53 PM 11/6/2009

My best bet could be your tps or you maf check those. Anyone else have any ideas?

check those sensors but i would also check the distributor they tend to get oil due to high blow by and a clogged pcv valve take the cap off and see if there is oil inside the distributor.

did you just check the basic fuel pressure, or did you check the fuel pressure regulator too?

if you didn't, just put the gauge back on and fire the car up. with it running, pull the vacuum hose off of the regulator and watch the gauge. pressure should rise with the vacuum disconnected. if not, you have a bad pressure regulator...