Additive to reduce black smoke on acceleration - Alfa Romeo Forum
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Muz
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Additive to reduce black smoke on acceleration

My 2.4 had it’s dpf removed about 3 years ago. I have noticed that on hard acceleration it is now pumping out quite a bit of black smoke. Is this something that I am likely to be able to reduce with an additive? I tend to use the best quality shell diesel fuel so am surprised to see this much smoke. Maybe it is something more serious?

Any suggestions welcome, apart from putting the dpf back on! The car lives in the middle of nowhere in the country so does not spend ages stuck in traffic and gets quite a few motorway runs too
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(Post Link) post #2 of 6 Old 1 Week Ago
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I cant say I noticed any more black smoke when I ran without a DPF, my car is remapped and never smoked before or after.

It's possible you have a boost leak, which would result in black smoke, probably more common than anything - how does it feel power-wise?
Have you had any work done to the EGR valve - this could be stuck open, giving similar symptoms

V-Power or even the Shell Fuelsave will likely have enough additives and detergents to avoid you having to use any additional additive - although I used BG244 on mine when I first bought it with reasonable results.

Fully agree with the DPF, these cars are killed by it, mine doesn't get used enough on my commute to keep it at optimum condition, so I have to take it for an italian tune up every couple of weeks.
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(Post Link) post #3 of 6 Old 1 Week Ago
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Basically, white smoke is unburnt diesel, black smoke is poorly burnt diesel, and NOx is high temp burnt diesel.

Poorly burnt diesel can be caused by rich running, which in turn can be caused by:
Poor oxination (e.g. boost leak or fault MAF)
Poor diesel evaporation (leaky or dripping injector, or faulty lambda)
It might also be caused by oil burning (stem valve seals or maybe piston rings) and/or slow combustion due to poor combustion pressure.

Of course on full load (acceleration) the engine will inject as much fuel as possible, to provide as much power as possible. This would magnify any small issue you might have.

Of course the DPF is designed to absorb this soot, and burn it off later when the car is not running full load (by leaning the mixture and increasing the exhaust temp to burn off the soot in the DPF)
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Quote:
Originally Posted by amfalconer View Post
I cant say I noticed any more black smoke when I ran without a DPF, my car is remapped and never smoked before or after.

It's possible you have a boost leak, which would result in black smoke, probably more common than anything - how does it feel power-wise?
Have you had any work done to the EGR valve - this could be stuck open, giving similar symptoms

V-Power or even the Shell Fuelsave will likely have enough additives and detergents to avoid you having to use any additional additive - although I used BG244 on mine when I first bought it with reasonable results.

Fully agree with the DPF, these cars are killed by it, mine doesn't get used enough on my commute to keep it at optimum condition, so I have to take it for an italian tune up every couple of weeks.
Thanks for the reply. Yeah itís only recently started doing it but the power is still there with no noticeable loss throughout the rev range. Accelerate gradually and I canít see any smoke, floor it and I can see plenty on acceleration but it then seems to stop belching it even at speed.

I did think long and hard about dpf removal but the car gave so many problems with it that Iíd have had to get shot of it. The difference not having one and after a remap is amazing, car has been a pleasure to drive since.
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(Post Link) post #5 of 6 Old 1 Week Ago
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Have you got access to a fault code reader, or even better, MultiECUScan? - as you'll be able to check certain things like injector correction values - a clue should you have injector faults, however, I thought running premium fuels should negate any injector faults caused by poor fuel.

A couple of bits you could check are unplugging the MAF to see if the symptoms are the same, often a dicky MAF won't flag a fault, but they do go bad, pulling and cleaning the MAP sensor on back of the manifold, checking the main turbo hoses, VAC lines and operation of the VNT vanes (unlikely as you seem to have power across the band).

Another culprit not mentioned is swirl flaps, these have a habit of leaking boost, specifically cyl no. 5 (egr end) - most of these cars, if left unmodified will now have a nasty coating inside the manifold of EGR soot and oil from turbo seal blow-by, typically thickest at flap no.5

Have a look for the 'power loss for diesels' sticky/guide on here, quite a bit about smoking under full power - my bet is on a boost leak through.
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(Post Link) post #6 of 6 Old 1 Week Ago
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i used to get a lot of smoke/soot (was running with dpf removed), i think the swirlflaps were part of the problem. Anyway i took the plunge and sent it to autolusso, they did the swirlflaps, put one of their on maps on it and refitted the dpf (so its legal) result is no smoke and it goes like stink

test you swirlflaps or look for a boost leak
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