Sign in to follow this  
90LS400Lexus

Smoke From Exhaust Upon First Startup, But Not Oil

Recommended Posts

I have noticed when I start my car for the first time of the day- smoke will come from the exhaust pipes for about one minute or less. Normally, I would think would be valve seals and oil burning, but it smells nothing like oil smoke and the car does not use any oil between oil changes. It smells exactly like gasoline- then the smell fades away and does not do it again until the next day- on the first start-up. Does this sound like I need some sort of fuel system tune up? Bad injector? Could my injectors be dirty? I have also noticed what I think is low fuel economy, but I may be wrong. I put gas in the car today and it was on 1/4 tank- maybe a little over. The mileage since I filled it up was 180 miles. Shouldn't I get a lot more than 180 miles to 3/4 tank of fuel? * This was mostly very easy and slow, stop and go city driving however. How many MPG do you get per tank full? According to my window sticker- I think it states 18 MPG city.

Thanks for any advice.

Share this post


Link to post
Share on other sites

Many people report that when the light turns on, that means there is 18 gallons gone from the tank.

On mine, the last "1/4" is less than the 1st and second "1/4", so I'll guesstimate that there are 14 gallons gone for your 180 miles, or about 13 mpg.

Yep, that's poor mileage, even for city driving, I think. You may have something wrong going on. I would have it checked out.

FWIW, I get about 350 miles at the 1/4 full mark on 90% highway driving.

Joe

Share this post


Link to post
Share on other sites

If you have a faulty gas gauge then you have no idea.

Fill the tank all the way up ,drain it till it stalls and keep a jerry can to fill it up.

If you never get right down to the bottom you may have deposits of silt in the tank but there is a filter in the tank before the pump and after to take care of contaminents.

That will giev you a more precise reading than any other.

Also all gas gauges are made to be a meter not an exact reading. As tehy all are slow until 1/2 then seem to drink gas. It is no different than any other car as it is made to meter the last 1/4 of the tank more precisely than the first half. After all do you really care if you are 8/10 or 9/10 full. It would make more of a difference on a 500 mile drive ,knowing how much you have as the last half is usually more important

Share this post


Link to post
Share on other sites
If you have a faulty gas gauge then you have no idea.

Fill the tank all the way up ,drain it till it stalls and keep a jerry can to fill it up.

If you never get right down to the bottom you may have deposits of silt in the tank but there is a filter in the tank before the pump and after to take care of contaminents.

That will giev you a more precise reading than any other.

Also all gas gauges are made to be a meter not an exact  reading. As tehy all are slow until 1/2 then seem to drink gas. It is no different than any other car as it is made to meter the last 1/4 of the tank more precisely than the first half. After all do you really care if you are 8/10 or 9/10 full. It would make more of a difference on a 500 mile drive ,knowing how much you have as the last half is usually more important

I think you may have my problem mixed up with someone elses. Actually, my fuel guage is fine. It goes to full when filled up and works properly. On one of my replies to someone elses fuel guage problem, I did mention that my guage is slower going up than my other cars, but from all of the other Toyotas I have owned- the slower guage seems normal. My main question is why my car smokes upon initial start-up, with the smoke having a gasoline smell. No oil smell at all. The car runs perfectly, with plenty of power, but still think something in my fuel system needs to be cleaned. Thanks again.

Share this post


Link to post
Share on other sites

:rolleyes: Most likelly you are burnnig Power Steering Fluid. there are two lines that come from the back of the power steering pump and connect to the intake manifold, you can disconnect them and plug the intake niples and drive for few days, you will notice the smoke is gone. If so, the valve is bad and needs to be replaced. Keep an eye on the power steering fluid, you do not want to run dry...

I had the same problem, I went ahead and did the test, and replaced the valve. Problem solved.

I can send you a picture of the lines gong in to the throtle body.

:ph34r:welgaby@msn.com :ph34r:

Share this post


Link to post
Share on other sites

Thanks, but if you notice in my first post, that the smoke is the smell of gasoline and only does it upon initial startup- for less than a minute. I do not think that anything (even if it was on the exhaust) would burn right at start-up, as the engine would be cold. Also, my power steering does not have any drips from it, so I do not think that it what it is. Thanks anyway.

Share this post


Link to post
Share on other sites

Well,

For a 13-14 year old car if the Throttle body hasn't been cleaned it sure wouldn't hurt anything- I don't know if that will help the problem for sure but it's a good start.

There is a GREAT PICTORIAL PROCEDURE for this somewhere (temp lost in the Crash) buy I'm sure it will surface.....

I've also read from Lextech2k3 that this isn't necessarily a bad thing (the smoke @ startup) because the car is older.

I does sound more like a too rich mixture problem

Share this post


Link to post
Share on other sites

Actually, smell of gas on startup is normal. When the car is cold, it runs rich due to the fact that O2 censors are still cold and not working yet. BTW, rich means that too much gas is getting into combustion chambers. As the result, some gas is leaving the combustion chamber unburned, hence the smell.

Share this post


Link to post
Share on other sites

It must be a little "richer" than normal, because of the smoke. It looks like blue smoke (which would indicate oil), but it smells NOTHING like oil burning. Gasoline smell only. Thanks again.

Share this post


Link to post
Share on other sites

Actually, smell of gas on startup is normal. When the car is cold, it runs rich due to the fact that O2 censors are still cold and not working yet. BTW, rich means that too much gas is getting into combustion chambers. As the result, some gas is leaving the combustion chamber unburned, hence the smell.

Finally, the correct answer. :cheers:

Share this post


Link to post
Share on other sites

I agree that it is normal to have a little smoke on start-up. Actually the smoke is condensation burning off and it smells a little like varnish to me. Obviously, this is much more noticeable when it is cold outside, and baby it ISS cold outside!

Share this post


Link to post
Share on other sites
I agree that it is normal to have a little smoke on start-up.  Actually the smoke is condensation burning off and it smells a little like varnish to me.  Obviously, this is much more noticeable when it is cold outside, and baby it ISS cold outside!

Yes- my car seems to do it more when it is colder outside. You are right about COLD. We were only in the lower 30s today and our normal high for todays date (January 10) is in the mid 40s. :huh: Big change from last Sunday's 72 degree high. :) I am ready for spring.

Share this post


Link to post
Share on other sites

My guess is you're probably looking at two seperate issues.

1. As mentioned before, when a car is started especially when cold it runs rich, and sometimes you'll get a gas smell. This is more or less normal.

2. As the piston rings and seals get old they become brittle, especially when cold. This allows a phenomenon called "blow-by" to occur where small even trace amounts of oil are forced by the brittle piston rings into the combustion chamber and then are burned out, which would explain your light blue oil smoke. When the engine gets warm the rings become more pliable and the blow by stops. Some engines will do this right out of the box (its a VW characteristic) and most will begin to do this as they age.

No big deal...

Share this post


Link to post
Share on other sites

Much of the white smoke seen when cold is just water vapor. Look at anybody's exhaust until the whole system warms up.

The smell and poor mileage is another problem. My 1990 LS400 with 200,000 mi. normally goes around 400 mi between fillups with mixed driving conditions.

Share this post


Link to post
Share on other sites

But if its hanging blue smoke like he's describing its not water vapor. The difference between the two is quite obvious...

Share this post


Link to post
Share on other sites
Much of the white smoke seen when cold is just water vapor.  Look at anybody's exhaust until the whole system warms up.

The smell and poor mileage is another problem.  My 1990 LS400 with 200,000 mi. normally goes around 400 mi between fillups with mixed driving conditions.

The smell is burn't up gases remaining in the chamber from the previous drive.

Most of us with high mileage cars have used non-synthetic oil in the past. According to Mobil, synthetic oils were designed to reduce "wearing of cylinder walls". Since synthetic oils were not available before 1993, and the manufacturers told us not to use it in our engines, we are suffering.

White smoke is related to the above, to some degree.

Share this post


Link to post
Share on other sites
Much of the white smoke seen when cold is just water vapor. Look at anybody's exhaust until the whole system warms up.

The smell and poor mileage is another problem. My 1990 LS400 with 200,000 mi. normally goes around 400 mi between fillups with mixed driving conditions.

Of course there is steam (vapor) when it is cold out, but I can also see the blue lasting a little longer. Whats peculiar, is that there is no oil smell at all. Oh well- no big deal I guess. Thanks again folks.

Share this post


Link to post
Share on other sites

AFter reading Matthews very long post on oil, I feel very fortunate that the previous (original) owner of my car used synthetic oil since it was new. While it took me quite awhile to read and comprehend, it makes it blantently obvious that synthetics are superior in every respect. As to the condensation emitted upon startup, I think it looks good on a cold day to see wiffs of steam coming out of the duel exhausts.

Share this post


Link to post
Share on other sites

and synthetics were available long before 1993. Amsoil has been making it for years, even Mobil 1 was out before 93

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this