LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

Black smoke on startup

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Old 03-24-08 | 12:09 PM
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Default Black smoke on startup

When I start my car my friend says there is some black smoke coming from my exhaust, the outside temp is 35'F.
Old 03-24-08 | 01:23 PM
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If it truly is black black smoke -- Then it is likely is the cause of incomplete fuel combustion. Which can be caused by any number of common factors.

Black-Blueish smoke is oil burning,.. sometimes hard to tell the two apart. Most people assume the car is 'burning oil' when they see black smoke or any smoke hehe.. But that isn't the case many times --

Check your oil levels, coolant levels, PS levels, and Fuel economy over say the next 300-400miles. It should clue you in.
Old 03-24-08 | 04:20 PM
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I just seafoamed my engine so fuel economy will not be typical this tank. I just topped off my PS Fluid about a week ago. My coolant level is about half-full ( not half-empty hehe). I will check my oil levels tomorrow, when it isn't 30' and windy lol.
Old 03-25-08 | 02:28 AM
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Keep an eye on that PS fluid as well. But you could have a rich mix going,.. among other things. (If its just a rich mixture, your not in immediate danger,.. better rich than lean, imo)
Old 03-25-08 | 08:05 AM
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I already know that I have a PS leak, sorry I forgot to mention that.
Old 03-25-08 | 08:26 AM
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PS leaking into intake from ACV? Or just a leak dripping on ground?

The PS smoke can look darker sometimes -- Not quite black, but dark blue. If the fluid was really burnt I suppose it could go black.

I wouldn't suspect it though, you should find out relatively soon by monitoring fluids. If none go down, then it is likely an air/fuel ratio error.
Old 03-25-08 | 10:06 AM
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Well there is a little bit of liquid coming out of my tail pipes, but I just suspected it was water.
Old 03-25-08 | 10:34 AM
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Hey consider this man. If you have a high mileage vehicle over 150k your fuel injectors have taken a beating all of those years.They get worn out over time and I bet you have the oem ones in there still right? When you have the car off after a drive the leftover pressure that isn't put back into your tank bleeds threw your injectors that are worn. The gas goes into your cylinders and then you have extra gas on startup. If it is blue smoke it is guaranteed a oil leak internally. If you have white smoke then you have internal coolant leaks not good at all. Power steering would not get into your engine totally different closed system non related to black smoke out of the exhaust. Anymore questions ask away man later>>>.
Old 03-25-08 | 10:43 AM
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Thanks bro, I will have to watch someone else start my car, just to see for myself. My friend could be colorblind for all I know lol.
Old 03-25-08 | 12:40 PM
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Originally Posted by Ls4hundred
I just seafoamed my engine .
i say this has caused it..
Old 03-25-08 | 12:44 PM
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Originally Posted by SHOLEXMAN
Hey consider this man. If you have a high mileage vehicle over 150k your fuel injectors have taken a beating all of those years.They get worn out over time and I bet you have the oem ones in there still right? When you have the car off after a drive the leftover pressure that isn't put back into your tank bleeds threw your injectors that are worn. The gas goes into your cylinders and then you have extra gas on startup.
Valid point -- But this isn't always the case, nor would I bet is a common case in high mileage LS 400's. None the less it happens, and does cause a rich mixture on start.


If it is blue smoke it is guaranteed a oil leak internally.
Not necessarily,.. PS fluid can and does burn blue.


If you have white smoke then you have internal coolant leaks not good at all.
Not always -- White smoke can be produced from your catalytic convertors -- or after just washing your car and getting water up the exhaust pipe. Basically H20 burns off white, of course. Then you have a similar effect when the ambient temperature drops in the 40's or lower.

If you smell a 'sweet' smell from your 'white' smoke, and your level in your reservoir is going down constantly, you have a leak.. not good. If your level is staying exactly the same, you look for another reason for the 'white smoke'.

Power steering would not get into your engine totally different closed system non related to black smoke out of the exhaust. Anymore questions ask away man later>>>.
Yes it would and does. Many cars it cannot, because they don't have an ACV -- This valve is prone to go bad on the LS 400's -- When it does,.. PS fluid is allowed to pass through the vacuum hose into the intake manifold. Hence it gets into your engine, combustion cycle, and produces smoke. (Often after you park the car it gets sucked in from the vacuum but not burned.. ) - Then when you start the car the next day that 'larger amount' is burned all at once and you get a noticeable puff of smoke.

This is black smoke though -- So none of that is relevant for this guys question. -- What do you have to say about black smoke?
Old 03-25-08 | 12:45 PM
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Originally Posted by Ls4hundred
Well there is a little bit of liquid coming out of my tail pipes, but I just suspected it was water.
It is -- Seafoam causes your Catalytic convertors to work overtime,.. You will get some drip from the exhaust, and some white smoke for a lil while as a result.

Water is nothing to worry about, and is actually good from the exhaust -- Providing it isn't 'coolant' -- big difference in H20 and Coolant mixture. Also very easy to distinguish between the two with smell, and feel/color.
Old 03-25-08 | 03:37 PM
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Well I haven't smelled my exhaust lately lol, but I will next time.
Old 03-25-08 | 04:55 PM
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Okay man you didn't have to pick apart everything I said and make it seem like I was wrong on every subject. You have me on the power steering issue my bad on that part ,but seriously I didn't think your were going to get all nuts."This is black smoke though -- So none of that is relevant for this guys question. -- What do you have to say about black smoke?" Overkill man don't get all pissy about it.
Old 03-25-08 | 09:02 PM
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black smoke sound like extra gas in the system do you ever get the car on the highway and run it for a good 10-20 miles to clean it out also go to your local pep boys craigens or auto store and get a big bottle of lucas fuel injection cleaner and give a good amount of the fluid with a half or quarter filled tank take the car on a good run this will clean the injectors normally. I have 200298 miles on my 91 lexus and no injector problems. I always use lucas fuel injection cleaner and the car runs fine on 89 octane here in California and with our gas that is doing good. Now I don't know how the first owner took car of the car I hope this helps and get the power steering fixed or get ready to replace the alternator which is expensive. Good luck with the lexus the worlds best built car. by the way water coming from the tail pipe in normal just a few drops if it smells or looks white take it to a radiator shop and see what they say.



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