this morning i noticed, when the car is idle (IS250), i saw white smoke coming out of both exhaust.

Is this normal ? I didn't pay much attention before.

 

How cool was it outside at the time?

 

it was around 8:00 AM in the morning
probably 70-75 degree

 

Well that can happen when its cool outside.

 

white smoke is bad......atleast if it doesn;t go away

Things to check head gasket....check coolant for any oil and vice versa

 

Was this the first time that you started your car in awhile? Sometimes if the car isn't started for a long time, the gas inside the tank can go through minor phase separation and go a bit stale. This could lead to a white smoke for a few minutes.

 

are u sure it's not steam? a lil white steam in the morning is normal during the first few minutes of driving. now if it's thick white smoke billowing from your tailpipes, then yeah get that checked out.

 

Not sure where the OP lives, but you're correct in that some steam is normal due to sudden temp changes on the exhaust when the car is started. If the air is humid and evening temps go down, it is possible for the exhaust to have some moisture when you fire her up in the morning.

However, I've had smoke before when I fire up my prior cars (enough to say WTF??), when they've sat unstarted for some time (a week or so). The gas inside the car is nothing but hydrocarbon compounds that vary in molecular weight, and if unstarted for some time, the gas can go through some phase separation, so you wind up with combustion of "unmixed" gas (think of it like oil and vinegar separating in your bottle of Italian dressing). Unmixed gas in a tank will result in high molecular weight compounds sinking to the bottom of the tank, and lighter weight compounds floating to the top. Hence, when you combust the gas that isn't mixed, you're burning off one of the phased layers, and not normal gas that has been mixed.

When you drive the car and shake up the gas, it gets mixed again, so the smoke goes away.

 

Something ive noticed here, its always ppl from texas that seem to know alot about gas/oil stuffs. If you also look at the numerous synth/dino threads the most technical answers come from the TX members.

 

Hogwash! Gasoline doesn't separate for months. Your car can sit for an entire month and not have a problem with separation. My Supra has sat for months on end and never had the issue you describe. Ever. You'll lose the oil from your bearings and start dry before the gasoline separates.

Exhaust "smoke" in a new car is from steam. No matter where you are, there is steam that comes out of the exhaust whenever the engine is running. Remember the fundamentals of hydrocarbon combustion? HxCx + O2 = CO2 + H2O. The H2O is hot so you generally don't see it, but when the exhaust piping is cool, the H2O condenses and forms visible steam. This is also why mufflers rot from the inside out, not the outside in the way many people mistakenly believe they do.

The only time you need to be worried is if the "smoke" is bluish or if it does not subside after a few miles. If the smoke is bluish, then it is oil burning, not water vapor. If it is water vapor but does not stop within a few miles you have a cooling system leak into the exhaust, and usually this means a blown head gasket or a cracked head or both. You would also see water in the oil, and your performance would suffer. It is extremely UNlikely this is the case with a new car, or even a car only two years old.

 

yeah, the car has been sitting for about a week or so. I have not take it for a spin, I will take it for a spin today, and see if the smoke is still there or not

 

Yeah, I'm familiar with combustion and the production of CO2 and H2O as products. However, as one who is familiar with oil refining, I can tell you that the gas produced for the pump is held to strict standards, but is still far from perfect. Cars that sit for awhile, especially if water may be present in minor quantities in the tank, can have a gas tank that succumbs to phase separation.

Since ethanol has replaced methyl-tert-butyl ether (MTBE), as the oxygenate of choice, smaller quantities of water can cause phase separation and result in ethanol + water going to the bottom of the gas tank. The car doesn't need to sit for 6 months for this to happen. Oil (hydrocarbon layers) always float above the water + ethanol mix. Ethanol and water don't burn too well as fuel, so it is possible to have some white smoke from the exhaust (more than just steam).

I welcome challenges to this train of thought, but I've noticed it in my own cars, and I've been told that this is a risk with ethanol as the oxygenate of choice.

Appears that the OP did let the car sit for awhile, and like it or not, there could be enough phase separation in today's gasoline to produce white smoke when the car is fired up. Remember, gas has changed since the exclusive switch to ethanol in 2006.

 

Well, some would disagree with you, but I've been a loyal employee of a large oil company for 10 years now, so I have my perspective on things.

The oil company? You know it well, just look for the yellow pectin symbol when you go to fill up gas.

 

Phase separation isn't an issue at all for at least two weeks, and in most cases a month. There are also dialkyl carbonates added to fuel to extend this life.

Click here for some practical recommendations.

I saw nothing in the OP's posts to indicate the car had been sitting for a long period (longer than a month.)

 

the car has not been sitting for more than a month.
i tried it again today, and i did not see the white smoke coming out of the exhaust (it was around 90 degrees)
thanks for everyone who responded