Smokey diesel clouds - cause and worst offender? Vpower mpg!
Smokey diesel clouds - cause and worst offender? Vpower mpg!
Author
Discussion

fjord

Original Poster:

2,143 posts

168 months

Wednesday 6th March 2013
quotequote all
Couple of things rolled into one topic.

Behind an Octavia tonight which was about 6 years old. Every time he booted it, a huge cloud of black soot was chucked out of the back. It was enormous. Much bigger than my own cloud... He was clearly doing it on purpose to me aswell.
Im not going to complain, i made a topic not so long ago confirming that i like to do it too wink
As usual, it descended into a topic of PH butthurt, with someone accusing me of being responsible for cancer... rolleyes

Anyway, before we get bogged down on this again (and we clearly will), what causes it and how is it done? He seemed to drop of the gas, then give it a bootfull. Does it only do it at certain revs, or when the turbo is spooling down, or at a certain time spent at low revs or something? Are some cars worse offenders than others?

Also, banged £90 worth of v-power diesel in the 320 yesterday. MPG has increased on the OBC (albeit only over 50 miles) from 33.8 to 37.9... eek

Im unsure if this is a temp increase or not. I got 500 miles from a tank using the normal stuff, so i'll see how it pans out at the end and do a more accurate calculation, however over the last 3 tanks, i've found the OBC to be pretty accurate. Anyone else get much different mpg when using expensive jungle juice?

anonymous-user

85 months

Wednesday 6th March 2013
quotequote all
I wish the rules could be changed on how they work out VED, because I bet that Passat chucking out all that soot is about £130 a year.

twink

392 posts

180 months

Wednesday 6th March 2013
quotequote all
fjord said:
Couple of things rolled into one topic.

Behind an Octavia tonight which was about 6 years old. Every time he booted it, a huge cloud of black soot was chucked out of the back. It was enormous. Much bigger than my own cloud... He was clearly doing it on purpose to me aswell.
Im not going to complain, i made a topic not so long ago confirming that i like to do it too wink
As usual, it descended into a topic of PH butthurt, with someone accusing me of being responsible for cancer... rolleyes

Anyway, before we get bogged down on this again (and we clearly will), what causes it and how is it done? He seemed to drop of the gas, then give it a bootfull. Does it only do it at certain revs, or when the turbo is spooling down, or at a certain time spent at low revs or something? Are some cars worse offenders than others?

Also, banged £90 worth of v-power diesel in the 320 yesterday. MPG has increased on the OBC (albeit only over 50 miles) from 33.8 to 37.9... eek

Im unsure if this is a temp increase or not. I got 500 miles from a tank using the normal stuff, so i'll see how it pans out at the end and do a more accurate calculation, however over the last 3 tanks, i've found the OBC to be pretty accurate. Anyone else get much different mpg when using expensive jungle juice?
It can be many things causing it. A boost leak in a hose from the turbo, a bad fuel map if it's been remapped, EGR valve faults have been known to cause it. If he looked like he was slowing down the speeding up it will smoke whilst the turbo is spooling up again but this is pretty much down to a bad engine map.

It's also entirely possible he's stuck a £20 Ebay tuning box on it (plugs into the common rail pressure sensor and fools the engine ECU into seeing less pressure than there acutally is in the fuel rail, so it turns up the pump pressure to compensate. Thus throwing in more diesel than the ECU thinks is actually going in.

I'd suspect either a tuning box or remap to be honest. Especially if the exhaust looked like it was modified. My Vectra had a remap done by a so called professional tuning firm and having looked at the file myself, the injection duration was way out. Meaning that in the process of tuning it further it threw more and more soot out the back. To the point of after 4000 RPM, it could quite easily blot out the car behind. This has since been fixed and even screwing the tits off it, I get a wisp of smoke at most. And it has straight through exhausts so nothing to clean it!

Also, Google the Evry mod.

Si_steve

1,190 posts

221 months

Wednesday 6th March 2013
quotequote all
Can't it also be caused by the engine labouring off boost...or is that on the older DI engines rather than the newer commonrails?

I don't know to be honest, only really had petrol cars. Usualy when I see cars doing that it's old vw's and they just look broken...Easiest thing to do is overtake them and forget about it.

twink

392 posts

180 months

Wednesday 6th March 2013
quotequote all
That tends to be more the older engines. The fuel maps and smoke limiter maps on a modern diesel shouldn't allow it to throw clouds of crap out of the back by injecting too much fuel before the turbo has spooled up.

Si_steve

1,190 posts

221 months

Wednesday 6th March 2013
quotequote all
That was my thought on the newer engines, that they are more an EFI system than the old clockwork engines tongue out

SturdyHSV

10,443 posts

198 months

Wednesday 6th March 2013
quotequote all
I always assume it's deposits in the intake manifold built up due to EGR, that then gets sucked through and out when enough right hoof is applied.

Never paid too much attention to diesel engines to be honest.

NISaxoVTR

268 posts

200 months

Wednesday 6th March 2013
quotequote all
Too much diesel, not enough air. Happens a little on some standard cars during turbo spool up, happens a lot on 'tuned' cars. Unlike petrol engines too much fuel doesn't decrease power so there are lots of diesel tuning experts who one way or another dump in more than enough diesel to get the max bhp.

Evoluzione

10,345 posts

274 months

Wednesday 6th March 2013
quotequote all
It could be one or a few of many things: Running on Bio diesel, Faulty EGR, overfuelling, particulate filter removed or just plain worn out....

Caulkhead

4,938 posts

188 months

Wednesday 6th March 2013
quotequote all
fjord said:
Also, banged £90 worth of v-power diesel in the 320 yesterday. MPG has increased on the OBC (albeit only over 50 miles) from 33.8 to 37.9... eek
Well that's cheered me up, my 274bhp petrol turbo 4WD Mazda 6 MPS only does 4mpg less than your 320d! smile

Aside from that the single most smokey diesel car on the planet is the one my dad ran in the early 90's - a Montego turbo diesel. Full throttle in 2nd to the red line was sufficient to completely obscure following vehicles and I'm not exaggerating.

Meths

2,109 posts

167 months

Wednesday 6th March 2013
quotequote all
fk, My range-rover was more economical than your car!

windy1

396 posts

282 months

Wednesday 6th March 2013
quotequote all
Swirl flaps and EGR faults mainly. The signs of a very sick engine that needs work to get it running properly again.

snotrag

15,725 posts

242 months

Wednesday 6th March 2013
quotequote all
I just wanted to add, but I think others have already said it....

If you only get mud 30s mpg, what's the decking point! A 320i petrol will do that no sweat!

V88Dicky

7,373 posts

214 months

Wednesday 6th March 2013
quotequote all
snotrag said:
I just wanted to add, but I think others have already said it....

If you only get mud 30s mpg, what's the decking point! A 320i petrol will do that no sweat!
bks. ALL diesels are more economical than petrols, especially when you only do a few thousand miles per year. They sound better too, are WAY more reliable, more powerful and generally just nice to drive.

Never ever seen one chucking smoke out either, dunno what that's about.

fjord

Original Poster:

2,143 posts

168 months

Wednesday 6th March 2013
quotequote all
snotrag said:
I just wanted to add, but I think others have already said it....

If you only get mud 30s mpg, what's the decking point! A 320i petrol will do that no sweat!
It's probably got a broken thermostat.

Cant be arsed to fix it/diagnose other cold running issues.

Kolbenkopp

2,345 posts

182 months

Wednesday 6th March 2013
quotequote all
NISaxoVTR said:
Too much diesel, not enough air.
Most likely this. As for the cause we can only speculate, probably some not so efficient engine tuning...

bp1000

873 posts

210 months

Thursday 7th March 2013
quotequote all
Perhaps he remapped it or has a leaky injector/s

Older cars are also dpf-less and I've seen these great plumes before too. They are so dirty for the atmosphere and pedestrians. I now have a 5L v8 that I reckon is better for the local environment than that but I probably pay nearly £400 more for it in tax per year.

AnotherGareth

215 posts

205 months

Thursday 7th March 2013
quotequote all
fjord said:
what causes it
Another possibility not explicitly mentioned yet (unless I missed it) is a damaged (holed) intercooler.

cra1gy1989

293 posts

175 months

Thursday 7th March 2013
quotequote all
My fab vrs has been remaped and it smokes like f@@k put foot down wait for boost look in rear view and its like someone has set rubber on fire behind me, don't know why? Maybe overfueling?

sparkyhx

4,200 posts

235 months

Thursday 7th March 2013
quotequote all
wifeys car did this - replaced EGR valve sorted it