Diesels accelerating - big clouds of black smoke- explain??

[Steameh]

Diesels make soot, Petrols make flames.

But which is better?

[blueg33]

LuS1fer said:

They all bloody do it, old or new. Hate them.

No they don't!

[Kitchski]

I always thought it was a pre-warning to others to not mess with this player's TDI as it will smoke you! The more smog, the more power!

[supersingle]

blueg33 said:

LuS1fer said:

They all bloody do it, old or new. Hate them.

No they don't!

Oh, yes they do!

[Deva Link]

supersingle said:

blueg33 said:

LuS1fer said:

They all bloody do it, old or new. Hate them.

No they don't!

Oh, yes they do!

If they've got dpf's they don't.

[Bill Carr]

My Primera dci doesn't do it. The Passat I was following this morning was chucking out regular gulps of the stuff (presumably at every gear shift/throttle resumption?)

[LuS1fer]

I've seen all makes and varieties of diesel do it. Those who say they don't are clever in driving and sitting behind the car looking at the exhaust. Quantities vary but you don't need a diesel badge to spot one.

[theyrenotTHATbad]

they did a bit on this in redline, something to do with when its running at best fuelling or over it, some people think its cool and keep the smoke on the arse of thier car to show how fast thier desiel is.

[twazzock]

Kitchski said:

I always thought it was a pre-warning to others to not mess with this player's TDI as it will smoke you! The more smog, the more power!

No smoke, no poke!

[y2blade]

twazzock said:

Kitchski said:

I always thought it was a pre-warning to others to not mess with this player's TDI as it will smoke you! The more smog, the more power!

No smoke, no poke!

[the_lone_wolf]

Munter said:

Hence the egr valves.

Thought EGR valves were there to reduce chamber temperatures and therefore Nitrogen Monoxide production???

[coley20]

I had a re-mapped 530d that used to smoke like mad under load, I`m talking really thick coulds of black smoke

[mph999]

LuS1fer said:

They all bloody do it, old or new. Hate them.

Nope, I've got a filter on the exhaust, as do most new diesels to meet emmissions. No black smoke at all out of mine - when cold, hot, or hard acceleration ... :0)

When the filter becomes full the car burns the soot off and the process begins again ...

Martin

[Munter]

the_lone_wolf said:

Munter said:

Hence the egr valves.

Thought EGR valves were there to reduce chamber temperatures and therefore Nitrogen Monoxide production???

Oops a read of Wikipedia suggests EGR can increase particulates in Diesel. I may have been muddled up.

[theyrenotTHATbad]

coley20 said:

I had a re-mapped 530d that used to smoke like mad under load, I`m talking really thick coulds of black smoke

GET HIM GUYS!
oh "mapped 530d" not mapped 335d

[V88Dicky]

mph999 said:

LuS1fer said:

They all bloody do it, old or new. Hate them.

Nope, I've got a filter on the exhaust, as do most new diesels to meet emmissions. No black smoke at all out of mine - when cold, hot, or hard acceleration ... :0)

When the filter becomes full the car burns the soot off and the process begins again ...

Martin

So when this happens, is there a 500ft high mushroom cloud produced, or what?

[_rubinho_]

V88Dicky said:

Torquey said:

I've never understood when you see some of the sh!te that comes out of diesels how they are so much cheaper on tax?
(well I'm sure the answer is quite simple but i've never bothered to think about it to be honest).

Surely these engine farts are far more polluting than a petrol engine?

Depends on what you class as 'pollution'.

CO2 unfortunately is classed as pollution these days, and taxed accordingly.


True air quality of course, is about particulate contamination, aka proper pollution.....smog.

Soot is a very efficient contributor to the greenhouse effect. This article suggests that reducing it would be a very effective way of combatting global climate change in the short term (and much more effective than controlling CO2 emissions). Soot is harder to measure, and ultimately tax, than CO2.

If you subscribe to the belief that human production of greenhouse gases is a significant contributor to global climate change at all that is.

[Chris71]

rfn said:

Soot built up in the exhaust which is burnt off when a load of hot gases are thrown down the exhaust. Usually happens when the engine is driven gently for a while then hard acceleration.

Regeneration shouldn't produce a lot of smoke though. It happens at very high temperatures, which lead to relatively clean combustion of the stored soot - it's not simply belching out the back.

As mentioned before it's basically just that diesels run a much richer air-to-fuel ratio than petrol engines and also the chemistry of diesel combustion lends itself more to particulate production.

Modern engines have got a lot better, principally because virtually all now have diesel particulate filters (the matter trap that collects the soot mentioned above) and this acts like a giant tea-strainer in the exhaust, physically trapping the soot. You ideally want a steady state with a reasonable amount of gas flow to regen, so the ECU recognises this state - ideally on a long motorway cruise - and post-injects to dramatically increase the temperature in the exhaust to about 1500 deg C mid-brick.

[bodhi]

My 2004 320d does this, I just use it as another excuse to take the 328i instead.

[the_lone_wolf]

Munter said:

the_lone_wolf said:

Munter said:

Hence the egr valves.

Thought EGR valves were there to reduce chamber temperatures and therefore Nitrogen Monoxide production???

Oops a read of Wikipedia suggests EGR can increase particulates in Diesel. I may have been muddled up.

I only know because my DERV has been playing "James Bond" recently and I've been wondering what I can clean up. I was leaving long black marks on the road pulling away hard from a standstill but they weren't from the tyres...

A good mainland blast, "Italian tune up" style and it's clean as a whistle, no visible smoke from the driver's seat - may be psychological but I'm sure it's pulling better as well...