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Discussion Starter · #1 ·
I'm thinking Petrol Electric will be the future for the next 15-25+ years..

I'm not that impressed by diesel engines, as they don't seemed to have solved the Soot coming out for the back yet. Or is it the way it's been driven?

Does your diesel engine product soot?

I have noticed some diesel car emit a very black (Not brown) cloud of soot just after they have moved off / travelling at about 5 MPH? Is the drive lazily dumping the clutch (Not feeding in the clutch) or labouring the engine? Sometimes it's bad enough, that I have to hang back for it to clear before driving forward / through it.
 

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Discussion Starter · #3 ·
I don't mean soot all the time... the new diesel engines are quite good now. I'm talking about just after idle or moving off in traffic? I've seen brand new cars do it too... it's a very black / blue smoke / soot mix... a cough if you like then every things back to normal... soot free..

Could it be that the drivers who would have normally driven petrol car and now have moved over to a diesel car and don't understand how to drive a diesel car...? I used to drive a Golf Tdi and it was a lot different then a petrol car had... turbo lag..
 

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They have sorted the soot issue out on new engines. It's called a particulate filter. Problem is not many manufactours are using them. Audi have only just introduced the filters on the new PD170.

New diesel engines also take a bit of time to bed in.
 

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There's also a couple of other issues -

Acceleration fuelling - the engine is being fed a "rich" mixture as they move off.

Demand for above-petrol performance leads to high-tech turbos, clever fuelling systems, etc., all in the drive to get more fuel and air into the engine, fast. A byproduct is always going to be soot.

And don't forget that attempts to reuse the exhaust gas to cut emissions is met with howls of protest - bypassed your EGR valve, anyone?
 

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I only get soot, after the wife has had the car and without me driving it for a few days, but my right foot soon clears it all out[:p]
 

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And don't forget that attempts to reuse the exhaust gas to cut emissions is met with howls of protest - bypassed your EGR valve, anyone?
I didn't think this was possible, got anymore info about how to go about it?
 

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It is generally down to driving. If you take it easy and happen to do lots of short trips around town, the soot builds up in the exhaust, so occassionally it's goot to take it for a 'heavy right footing' down a bypass or motorway to clear it all out.

People behind you won't like it much though!!
 

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Got to admit I love my dirty diesel for its sootyness.  If someone is right up my chuff, I'll slow right down then plant the right foot and leave them in a cloud of black smoke.  They dont sit right up your ar$e again, as they think your car is about to blow up.  Can't say I've really noticed any soot other than when driven hard, even following my dads or my mates TDi there is no soot produced.
 

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Never seen no soot out of mine but who cares, you buy a diesel and expect it. When you notice soot popping out its probably a build up as the cars probably never gone past 1500rpm, and if they pull out in a rush it just forces all the build up out.

I thiink new peugeots have that particle (something or another) filter, you look up their tailpipes and it is spotless but apparently you get very high service costs on these.

Keep it sooty and sweet!
 

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And don't forget that attempts to reuse the exhaust gas to cut emissions is met with howls of protest - bypassed your EGR valve, anyone?
I didn't think this was possible, got anymore info about how to go about it?
Two methods -

a) Use vagcom to adjust the settings,

http://tdiclub.com/TDIFAQ/TDiFAQ-7.html#g look at item J.

b) Clamp or otherwise block the vaccum hose leading to the egr valve.
 

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If you drive the car hard, then soot doesn't really become an issue [:D]

As somebody said, particulate filters are the way to solve it and a few engines have them, such as the PD170 and the Audi 2.7, 3.0 and 4.0 TDIs. However, the filters are costly, pretty bulky and add a bit of weight. I'd expect all diesels to get them soon in order to meet tighter and tighter emissions regs.

Also, don't forget Audi has now perfected the performance filter as a result of having 2 fitted to the R10 TDI Le Mans racer. At Sebring they were a bit chunky (couple of bulges in the bodywork) but by Le Mans they were smaller and the bulges had gone. So size shouldn't be an issue soon.
 

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"b) Clamp or otherwise block the vaccum hose leading to the egr valve."

Got a pic of that by any chance???? [:)]

B
Nope!

Go to the car.

Open bonnet.

Find EGR valve. (hint, big silver thing with a lever on the side. It's at the back of the engine bay, where the air intake pipe runs backward, then turns to enter the inlet manifold. Easy to spot.

Find the thin rubber hose leading to the silver bit (NOT the thing with the lever)

Pinch it shut.
 

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I've had by Bora from new and it started producing soot after the clock reached about 2,500 miles, and only then when I booted it.

95% of the miles are journeys of at least 20 miles, very minimal town driving.

After 3,500 miles I experimented by switching to Shell from Esso and the soot disappeared completely - even when booting it hard. The other change I noticed is that engine now sounds ever so slightly more "gruff" when accelerating.

Must say though, soot comes in handy when you get a plastic nova/corsa/106/clio latched onto your rear bumper!

(<mini-rant> I have no problem with these cars other than there is minority of peeps who drive them in my area seem to think it's cool to try and "push" the car in front. </mini-rant>)
 

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as u guys said particule filters ar slowly coming on diesel cars but the diesel fuel itself is also getting cleaner

but now on trucks they are introducing a product called ad-blue basically its urea and when added to the exhaust in combination with a catalitic convertor there is no soot or anything harmfull coming from the exhaust just water

i wonder if they will ever introduce it on cars
 

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I did my final year thesis on this issue about 6 yrs ago and they were just introducing the particulate filters then. The problem is they clogged up very quickly so they were looking at some type of catalyst that effectively burnt of all the unburnt hydrocarbon (soot) that was trapped.

The problem is an intial spike in fuel delievery when the accl is pushed. These are unburnt aromatic hydrocarbons and highly carcenogenic. Diesels are relatively still pretty dirty.
 
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