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Discussion Starter · #1 ·
Something I have noticed with the new Tiguan which is probably just new car syndrome but having not had a new car then it got me wondering.

How much exhaust smoke would you expect to see?

I expect some when cold but it is to the point I accelerate gently in 3rd and I can actually see the exhaust smoke in the rear view mirror.

This morning I drove the hour to work, checked it half way pulling from a junction and nothing so thought ok all good.

Pulled up at work, reverse into the space and again I can see the exhaust smoke rising past the rear window.

Round about 5-6 centigrade outside.

Just wondering if this is normal with newer cars nowadays or is it something I should be worried about.

Car just turned through 500 miles so could be as simple as still running in or even normal but as I say, my last new car was 10 years ago so exhaust smoke has always been a worry. Probably over analysing it though.
 

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Some answers to your question 'Newbeetler'....shame it is an american sight :roll:
Daniel Wallander, studied at University of Wisconsin - Eau Claire
Written 15 Dec 2016
It's not smoke you are seeing in cold weather when the engine is started cold, it is water vapor.

The water vapor is still there in warm weather, but because the air is warm you do not see it condense as you do when the weather is cold.

Water is a by product of combustion. When you stop your warm engine, the water condenses out into the exhaust system as the exhaust cools. The exhaust can suck air in from the outside as it cools, adding the moisture present in the surrounding air. This is why you see water dripping out of exhausts just after then first start up on cool or cold days.

This is normal. Nothing to worry about.
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Dilip Kumar
Dilip Kumar, Automobile engineer, petrolhead, motorcyclist
Written 18 Jan 2015
The answer is simple. The air-fuel mixture combusts cleanly only when the engine I.e the system is at a certain temperture. Any temperature below that causes incomplete combustion hence when cold a lot fumes exit the silencer and whej warmed up only a minimal amount of smoke or no smoke.
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Pete Lacey
Pete Lacey, Retired engineer,chemist, metallurgist.
Written 17 Jan 2015
It's not smoke it's water vapour. Car fuels burn producing lots of water. In cold weather it takes longer for the exhaust pipework to get hot enough to keep this water as invisible steam so you see it for longer. It does exactly the same in hot weather but for a shorter period.
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Lalit Khatri
Lalit Khatri, cluttered brain.
Written 22 Jan 2015
The most probable reason is presence of an automatic choke which senses the low temperature and increases the amount of fuel making it rich which is necessary to start the engine. This rich fuel mixture burns to give lot of smoke but quickly increases the temperature, which is detected by choke and it reduces the amount of fuel to normal. And now there is no smoke.
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David Wyatt
David Wyatt, studied at Auckland University of Technology
Written Dec 15
If you are talking about the white stuff coming out of the exhaust then it is not smoke. It is water vapour. One of the many byproducts of burning fossil fuels (petrol, diesel and gas etc) is water and when the car is cold or the weather is cold outside you will see that water vapour. When the engine is hot or the weather is hot you will not see it anything like as much or at all, that does not mean the water vapour is not coming out of the exhaust but rather that because the car or weather is hot enough that you just don't see it because it is dissolved into the air much faster.
 

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Discussion Starter · #3 ·
Thanks Stumpy

I had read the same article. That's what I think it is. Just seemed strange after I had warmed the engine but it is still cold today so all that does ring true.

Surprised it was enough to see in the rear view mirror
 

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Very signifcant with my Tsi when cold as petrol burns hotter than Diesel.
 

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I have a 2008 reg 2lt TDI tiguan. Which I bought last year. I have fitted a new inlet manifold and had the egr cleaned,. But it now has started to blow blue smoke out the exhaust occasionally. My garage is at a loss as to what is causing it, as it comes and then goes after one day in some cases. When it happens it is usually when the engine is warm and i am putting my foot down in 2nd or 3rd to change gear, into 4th and it stops, there is no loss of power or acceleration, no usage of oil in 3500 miles, in fact it is really just an embarrassment for the duration. On long drives it does not do it. Anyone have any thoughts? This week it is going in to have a check to see that there is no oil collecting in the boost pipe which then when there is enough is getting sucked into the engine
Thanks
Albert
 

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Alfaz.di.pi said:
I have a 2008 reg 2lt TDI tiguan. Which I bought last year. I have fitted a new inlet manifold and had the egr cleaned,. But it now has started to blow blue smoke out the exhaust occasionally. My garage is at a loss as to what is causing it, as it comes and then goes after one day in some cases. When it happens it is usually when the engine is warm and i am putting my foot down in 2nd or 3rd to change gear, into 4th and it stops, there is no loss of power or acceleration, no usage of oil in 3500 miles, in fact it is really just an embarrassment for the duration. On long drives it does not do it. Anyone have any thoughts? This week it is going in to have a check to see that there is no oil collecting in the boost pipe which then when there is enough is getting sucked into the engine
Thanks
Albert
Worn fuel Injectors or fuel pump can cause smoke so can worn valve seals or worn piston rings. How many miles has car covered, service history?
 

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Thank you for the reply, what appears to be the mystery is it does not blow blue smoke all the time, I am presently dealing with an independant garage, who is baffled with the symptoms, as there is no readily available reason why it does create the smoke. Today I visited our local vw Dealer to ask if they could offer a realistic reason, and the, first question they asked me was it legal. They eventually considered that it could be caused as the dpf was trying to do a regen, but was unable to do one correctly due to so much in the DPF. this is a possible solution as the milage is just over 100,000. it is now booked in to do a forced regen to see if that will solve the problem. There are no faults coming up regarding this, no DPF light or EML and the vehicle runs as normal all the time, apart from the blue smoke every couple of weeks or so.
Regards
Albert
 

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Hello again, I have had a couple of things done since I last posted. The forced regen was done successfully and they got it down to 0.04 gram I believe. I have also had a new clip and gasket fitted to the joint between the turbo exhaust and DpF filter, there was a lot of fumes getting into the cab. However I am still no further forward with my smoke problem. It only does it when it is hot, but does not do it all the time, it seems to be more prominent when I am in third and have backed off slightly then put my foot on the throttle, then when I increase throttle it stops, when I change up into fourth and give it the boot it does not do it at all. I am still not using any oil, the car seems to pull and run well, although I have noticed a whistle coming from the engine in the last couple of weeks that sounds very like an ambulance or police car around. Any Ideas anyone, I am not sure if it is doing it during a regen as I am not sure when a regen is being done. One thing I have also Noticed, when the car is warm/hot the idling when you come to a stop stays at 1000 rpm. if you turn the engine off then back on again it reverts back to 800 rpm, what would cause this, I have nothing on that needs more revs.
Regards
Albert.
 

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First of all are we talking petrol or tdi engine
Secondly what colour is the smoke
If it is cold outside you will get white condense out of both engine types and new tdi' so with adblue are worse
 

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