[unni.ak]

One of those things I've noticed is that deisel engines emit black smoke when under hard acceleration or being revved. It doesnt matter if its a beat-up old Fiat or a E Class Benz. While Petrols are cleaner. Even under hard acceleration they dont emit any "visible" smoke.

Any technical reason behind this? Is it that Petrol engines emit smoke, but then of the invisible type?

[dadu]

Black Smoke
This is due to a air to fuel ratio imbalance, either the fuel system is delivering too much fuel into the engine or there is not enough clean air (oxygen ) a few things to look for :

• Faulty injectors (injectors need attention at about 100.000 to 120 000 miles)
• Faulty injector pump
• Dirty air cleaner
• Turbocharger or intercooler faulty
• Problems within cylinder head, valves clogged up due to faulty EGR (exhaust gas recycling unit)

White Smoke
Normally means that the fuel injected into the cylinder is not burning correctly. The smoke will burn your eyes.

• Engine/pump timing out
• Fuel starvation to the pump causing the pumps timing not to operate correctly
• Low engine compression
• Water/petrol in the fuel

Blue Smoke
The engine is burning engine oil

• Worn cylinders or piston rings
• Faulty valves or valve stem seals
• Engine over full with engine oil
• Faulty injector pump/lift pump allowing engine oil to be mixed with the diesel

Source

[srishiva]

Even if you tune your engine, diesel will emit soot all the time. Even during not so hard acceleration, some soot is being emitted. You can either oxidise it or filter it out.

Quote: They emit a mixture of gases and fine particles that contain some 40, mostly toxic chemicals, including benzene, butadiene, dioxin and mercury compounds

[CR-V]

Black smoke with modern day diesel technology is more because of adulterated fuel than anything else, specially with cars like laura and e class.

[newcoolgadgets]

I agree with unni.ak. I too have noticed that modern multijet diesels like the Swift, Palio and Octavia, E Class all emit a black smoke when revved. Does this mean that these engines are not as clean or environment friendly than petrol engines. If both are Euro III, then how do you explain the black smoke from the diesels?

Keeping aside the cost difference of petrol and diesel in India, purely for comparison, which is a better and cleaner fuel given today's modern engines? Are modern petrol engines cleaner than the diesels? Or if both are Euro III, are they at par?

I think this discussion will be quite interesting.

[tush]

This black smoke and mostly the emission of diesel contains fine particles which are normally inhaled by us in our day to day travelling on the road causing different diseases. This is the reason why environmentalist are apposing passenger cars be allowed to be sold in Diesel... especially when Fiesta and Swift and other likes were crowding the roads of New Delhi and hence nullyfing the effect of use of CNG in the Public transport buses.

But as a matter of fact before blaming diesel for polluting is the Government of India making it sure that its not adulterated at any point between the distribution cycle untill it reaches the fuel tank of the vehicles.

[rjstyles69]

So what if its emitting black smoke ? Is the government gonna do something about it ? Nothing period.

I think they need to tackle this at the root, stop fuel adulteration. With that 90% of the problem is tackled.

[dadu]

Euro vehicle emission norms are defined by the EU and followed as standards in India too. Burning of any fuel causes pollution and these norms define the acceptable levels.

But to meet these specifications, one needs the specified fuel quality too which all oil companies in India are providing at source.

To reduce the emission levels in diesel the EGR valves and particulate filters are used.

So it would not be right to compare the Petrol Vs Diesel emissions as long as they are within their defined norms.

Originally Posted by newcoolgadgets

If both are Euro III, then how do you explain the black smoke from the diesels?

Keeping aside the cost difference of petrol and diesel in India, purely for comparison, which is a better and cleaner fuel given today's modern engines? Are modern petrol engines cleaner than the diesels? Or if both are Euro III, are they at par?

I think this discussion will be quite interesting.

[pgsagar]

Originally Posted by CR-V

Black smoke with modern day diesel technology is more because of adulterated fuel than anything else, specially with cars like laura and e class.

That's interesting. I thought modern meant better. So black smoke is in- thing these days?

But yes, I have seen modern CRdi engines emitting more smoke than old non-CRdi diesels like Zen, Lancer, Uno diesel etc. I have seen brand new Logans, Swifts, Innovas, Scorps, Vernas, Fiestas, Tatas, Skodas all behaving same when it comes to belching black smoke. Must be pretty embarassing when you step on the A-pedal in a swanky new Laura or Merc, and your rear view mirror turns black. Those following behind in even in a beat up beat-up petrol car will have an amusing scene to watch.

[tush]

Originally Posted by rjstyles69

So what if its emitting black smoke ? Is the government gonna do something about it ? Nothing period.

I think they need to tackle this at the root, stop fuel adulteration. With that 90% of the problem is tackled.

Ofcourse government is responsible... the law is governed by the government...oops or should i say that government is governed by the politicians... so whatever may be the root cause, unless n untill politicians feel its adulterated and the environment is getting polluted and they(not civilians) will fall sick and die something would be done...

[unni.ak]

I own a Fiesta, thats done 7000 odd kms. It smokes when stepped on!! And it doesn't matter which class of engine it is, expensive high-end diesel models smoke. So, is it just the way diesel engines are or is there something else to it?

[tush]

Why dont you just confirm from the service station and check for any other Fiesta done same number of KMS. Just push the paddle when the car is in neutral. That way you can compare if its only your car.

It could be something else, i mean the diesel itself. Ask any Indian and he will swear by that we Indians cannot gurantee if we are getting non-adulterated Diesel.

[unni.ak]

Originally Posted by tush

Why dont you just confirm from the service station and check for any other Fiesta done same number of KMS. Just push the paddle when the car is in neutral. That way you can compare if its only your car.

It could be something else, i mean the diesel itself. Ask any Indian and he will swear by that we Indians cannot gurantee if we are getting non-adulterated Diesel.

I did check for other cars that have done the same KMS. And this is a common site. Planning to check if the ford service engineers have anything to say about it. You must've noticed this too when you travel. All diesels smoke

[newcoolgadgets]

Originally Posted by dadu

Euro vehicle emission norms are defined by the EU and followed as standards in India too. Burning of any fuel causes pollution and these norms define the acceptable levels.

But to meet these specifications, one needs the specified fuel quality too which all oil companies in India are providing at source.

To reduce the emission levels in diesel the EGR valves and particulate filters are used.

So it would not be right to compare the Petrol Vs Diesel emissions as long as they are within their defined norms.

So does this mean that Euro III Diesel engines are allowed higher emissions levels than Euro III Petrols because diesel is a less refined fuel than petrol? If this is so how are their emission levels on par? Can someone throw light on this?

[anupmathur]

It is because a petrol engine is invariably working on or close to the ideal stoichiometric ratio of petrol and air (because the petrol is inducted in proportion to the air inflow), whereas in a diesel engine the pump is doing the 'metering'.
By the time the turbo spools up to the required rpm, excess fuel has been injected. This, for a moment, will cause 'unburnt/partially burnt' fuel to be ejected via the tailpipe.
The metering is governed by the throttle input.
There are ways to completely prevent this phenomenon but the price to be paid is 'unacceptable' to the end user - delayed response to throttle input, ie. linked to turbo rpm.
The issue is further compounded by the chemical characteristics and differences between the two fuel types.



If this does not quite represent the situation, someone please amend where deficient.