Have noticed lately that when I start the car form cold a quick puff of smoke comes out the back. If I turn off the car after a minute or so and start it again, theres no smoke so its just on initial start up.
Took the car for a spin the other night, got up next morning and just started the car and no smoke at all. I only let it run for 30 seconds or so as I was just checking it before I went to work.
About 6 that evening I started it for the first time since the 30 sec turn earlier that morning and got a puff of smoke again which confuses me as it was fine that morning.
Would it be possible that by just letting it run for 30 sec that morning that there was unburnt fuel still in the system and thats why I got smoke that evening.
The fact that it was fine that morning puzzles me. The puff is whitish in colour, cant be sure but its definitely not black.

Its an Sti version 2 (1996) and standard apart from a back box.

Cheers.

 

bttt

 

Im no expert on subaru engines but......

White smoke is burning oil, Black smoke is too much fuel ( Rich Mixture )

On most cars, white smoke after car has been standing for a while is often kn*ckered valve seals as oil will get past the valve seals due to gravity. On a impreza the engine lays flat so im not sure if this would still happen.

Could just be something like oil in your inlet manifold which has got there through the engine breathers which are attached to it.

Dont let this worrie you too much, as like I said im no expert and it may be something simple.

Wait and see what the experts on here say.

Maybe David at API Engines will see this and put you right..

Andy

 

If it's just on start up after it's been stood a while it might just be condensation built up in the exhaust

 

If it is when it has been stood for a while it could be oil coming down a valve guide or more likely coming past a seal in the turbo. Nothing to worry about particularly but keep an eye on it.

 

always thought blue smoke was oil ,white was water and black fuel but more than likely i'm wrong lol

 

White smoke is also unburnt fuel. Black smoke is fuel burnt without enough air.

On cold startup, scoobs run very rich for the first 5 to 10 seconds of running before settling down. White smoke, both from excess fuel and condensation is perfectly normal in this circumstance. If it has a full decat...the whiff of petrol is unmistakable too which again, is normal.

 

Thanks lads for all the help, this morning it was perfect again so Im not going to worry too much about it.

 

I always thought that white smoke is water, blue smoke combusted oil, grey smoke burnt oil.?

 

Mine does it, one puff per day....


I do not think it is anthing to worry about, if it keeps doing it you have an issue.

 

I did, I have.

 

Can you share your doings and havings?

 

There's magazines around specifically for that sort of stuff ! l'm not sure a public forum is the place.

Seriously, I advise him to take off the intercooler and looksee if there is any amount of oil in there. It will have come from either the turbo or from the breather system [ crankcase vents ] . Unless the car is using amounts of oil between services I wouldn't worry too much. Ditto noises, No noises is better news than otherwise.

The nuisance is that any amount of oil going through the intercooler means that you are running on a 2 stroke mix and weakening the octane again. Lack of octane means pinking etc etc.

But if you aren't using any great quantities of oil and the odd puff is all you have. Don't worry.

David APi Engines / APi Impreza

 

LOL about the magazines....

I seem to use a lot of oil, but only have one little puff of smoke when I first start in the morning. I also have a little hesitation around 4k rpm sometimes.

I spoke to Bulldog and they said being at 26k miles I am due a plug change at 30k miles, so perhaps that will improve things.

I will have to wait and see......

 

Thanks for your email also David,
Thats interesting regarding the fact that oil in the intercooler could reduce the octane level. If there is oil coming from the turbo does this mean that the seals need replacing and would this be apparent from looking at the turbo itself,
If its a result of the breater system, where is the culprit area here?
Thanks.

 

Turbo seals possibly, but that largely means a new or rebuilt turbo, as the seals are more like piston rings than seals in the conventional sense. Not as job that can be done outside a turbo shop. Oil residue on the alloy side [ compressor ] side of the turbo is leaky seals. Oil residue on the exhaust side will be serious, as the heat of the turbo usually fries the oil before it gets a chance to settle, thus any amount will be a large amount

Oil in the breather system is from crankcase compression, which is usually created by worn piston rings allowing compression pressure to pass by and pressurising the rest of the engine. Fumes naturally created are then driven up into the induction, rather than leaking out and wrecking the world for us. The fumes are oil rich and down goes your octane.

An oil catch tank alleviates most of this problem as a temporary fix, but will not hide the fact that the engine is wearing out.

That help?

David APi Engines / APi Impreza