Hey, so my uncle just gave my family a '94 Sentra XE. Great running car. So heres the story,

We drove it up from NC -> MD (my uncle's place to my place, 300+ mi) with no problem. Before the trip, added one qt of oil, it seemed low. So the next day, I did a mini tune up (I've done it many times). I say mini becuase the belts seems relatively new.
So here's what I did: NGK G-Power spark plugs, oil and oil filter (what a bad location of the oil filter!), air filter, and cleaned out throttle body.
Easy stuff.
Once I started the car, smoke came out of the exhaust. When I drove around a lil bit, every time I accelerated smoke still came out. Ok, thought it was normal due to the cleaning of the TB. After a while it stopped.
Then I went onto the highway, and only when I accelerate HARD, then white smoke comes out. :banghead:

What could it be? It drove perfectly fine on the way up from NC. Did I do something wrong? What could it mean? Thanks in advance

black smoke means too much fuel (rich) white smoke is water/coolant, and grey is oil

I thought black smoke was oil burning? Eh.. I always get this stuff confused. So, water/coolant? Improper ratio? Because I just filled the reservoir tank to the max level with water. The tank was below min that's why. That's all I did with the coolant. On the ride home there was no problem.

no no, I mean water/coolant is burning. your mixture has nothing to do with the smoke. are you positive it is white (not to insult your intelligence), because coolant makes WHITE smoke.

Well it looks white from the rear view mirror... could be a little bit gray-ish? Not sure, maybe I'll have a buddy drive it in front of me sometime.

Either or, how would I correct this problem?

well once you identify what is being burned out, you have to isolate where/how it is entering the combustion chamber. typically coolant is from a head gasket, however a crack head can also cause this. oil can also be a bad head gasket, worn rings, leaking valve seals, just to name a few. what kind of mileage does this car have on it ? does it smoke really bad, if not I would probably not worry with it.

Well I think any smoke coming out of the exhaust except steam is pretty bad. Usually only during quick acceleration like getting on the highway. It has ~141k mi.

Could it have anything to do with the PCV valve and its hose? When I replaced it, the hose a little bit cracked. Going to go to the dealer to get the hose this weekend.

Hope this helps...

Black smoke = incomplete combustion, the gasoline is not completely burning up before it leaves the cylinder, usually caused by by incorrect air/fuel mixture or a sensor malfunction, could also be caused by a weak ignition system.

White smoke = water/antifreeze is entering the combustion chamber and exiting the exhaust pipe as steam. In severely bad cases water will fill the cylinder and cause hydro-lock keeping the engine from moving when you try to start it. In 4 cylinder inline (straight) engines is usually caused by a bad head gasket or cracked coolant passage, can also be caused by a cracked cylinder wall in severely over heated engines or engines that froze during winter weather that did not have anti-freeze in them.

In V6 and V8 engines causes can vary.

If you are loosing water in the radiator and have steam coming out of the tail pipe constantly check your oil, if the gasket continues to go bad water can enter an oil passage eventually flooding your oil pan, it will mix with the oil and cause it to get so thin that engine damage can occur. Start by pulling all the spark plugs and doing a compression check. Highly suggested that you carry several gallons of water with you to refill the radiator (been there, done that).

Light/transparent blue smoke while you are accelerating = oil is being burned, can be caused by a lot of things.

Thick heavy blue smoke while you are accelerating = oil is rapidly entering the combustion chamber and being burned, usually caused by a bad head gasket or blown piston rings. Again, pull the plugs and do a compression test, may be hard to diagnose without an expert opinion on your particular engine.

Light gray smoke while decelerating = usually caused by bad valve seals or worn out valve guides, fairly easy to fix but requires a lot of work and time.

Wow thanks, that's a lot of good information. The radiator level is no problem. Haven't needed to add anything.

You're welcome :-)