Why does my car belch out a plume of black smoke when accelerating rapidly?

[gebbel]

I just noticed this yesterday as I accelerated from around 120km/hr to 150km/hr in a quick burst on the motorway. I have seen it in other cars...all older than mine.....and I'm a little concerned to be honest. I also notice a black plume of smoke when starting the car on a cold start...it disappears after a short while however.

The car has 200,000km on the clock, remapped and regularly serviced.

Is this just the car showing its age and mileage?

Thanks.

[chody]

y jetta 140 tdi does this everytime i floor it from slow speed and a diesel mechanic friend told me it was most likely the egr valve but as no other symptoms to leave well alone so as it is only on hard acceleration i will take his advise

[keemaklan]

On the motorway it was probably just the turbo catching up with the increase in fuel in the combustion chamber. Since the turbo hadn't caught up fast enough the unburnt fuel comes out as black smoke. Its very common during quick throttle and when putting your foot down in too high a gear when accelerating. Nothing to worry about.

You could check the air-filter too to make sure its clean and also think about giving the intercooler + boost pipes + EGR valve and inlet manifold flat a clean out at 200,000 kms.


Black smoke means diesel not burnt properly, only down to two options: Air or fuel. Too much fuel not enough air or too much air not enough fuel i believe.

My 2 cents.

[OVI82]

Mine does it too but only when I put my foot down.it wasn't like that before the remap,so that is also a factor.

[Crasher]

I suspect its age and the remap are causing at least some of the smoke. You could try fitting a K&M panel filter as they allow more air in which will reduce the smoking.

[Puresilk]

Hi

Mine did that before the re-map and still does it now and its on 174k, when i accelerate hard in any gear it chucks out black smoke.

I have seen this in many other diesels, and most recently an 09 REG bmw 120D chucked out a large ammount of black smoke whilst accelerating hard in front of me.

The only diesels that dont do this are ones with DPF I suspect (correct me if im wrong)

[sooty]

y jetta 140 tdi does this everytime i floor it from slow speed and a diesel mechanic friend told me it was most likely the egr valve but as no other symptoms to leave well alone so as it is only on hard acceleration i will take his advise

I had the same issue only last week and it was the egr valve!

[Puresilk]

I was behind a 09 reg passant 2.0 tdi again a few days ago and same thing black smoke when accelerating hard !

[irishejit]

mine does it really badly but then thats because my MAF sensor is on the way out(the tell tail stutter in power has started....again)

[John140]

I had one of these but with no remap from new, and if you nail the throttle in top gear at say 60 mph you would get a puff of black smoke. As others of pointed out it is almost impossible, under these circumstances not to. However a large amount of smoke that you can easily see in daylight in the mirror may point to something more sinister like the EGR not closing properly or in a timely manner. Depends really on what you mean by 'plume'.

[Puresilk]

Drove a 60 reg Citroen c3 diesel (crap I know) I floored it in first second and third, when I looked in my rear view mirror again a plume of black smoke, so unless u have dpf I think it's the norm when accelerating hard in a diesel to get this.