Turbo diesels

peanuthead

Just wondering if anyone could explain why alot of modern turbo diesels emit quite a lot of black smoke? I noticed this with the BMW's Audi's and Ford Transit connects for example. Is this just unburned fuel? Does anybody have any explanations?

Like I know diesel won't burn as clean as petrol, but to me they seem very smokey. Maybe the ones I've noticed have been tuned in some way, a re-map or tuning boxes?

Any thoughts?

stratos

well most diesels emit black smoke to some extent. it's just soot, well the green party seem to think it's just soot. anyway a turbo will dump unburned fuel into the exhaust and the diesel burns away sootily. a Blocked air filter will cause the same effect causing black soot as the diesel mixture becomes too rich. I used to drive a sherpa van :rolleyes: it would suck the bonnet inulation into the air intake and then do an F4 phantom impression leaving clouds of black smoke. ah gawd be with the days. oh rats here they come again:mad:.

peasant

It's not unburned fuel, but partially burned fuel and soot.

The burning of the fuel in a diesel engine is not as controlled as in a petrol.

Diesel is self igniting due to compression and heat wheres petrol gets ignited by the spark plug. Therefore there is less control on when exactly the fuel will ignite and under full load not all of it gets burned completely.

Add to that the fact that diesel always burns with a lot of smoke and you've got your answer.

BlackWizard

Why does smoke come out of the exhaust in the morning though. When ever I seen other diesels on the road start of even my own, there does be a lump of white smoke which shoots out. It goes away after a few seconds.

I hope this is normal..

JohnCleary

My 320d doesn't emit any black smoke/soot

Having said that i've just had the turbo re-conned, changed the PC's, cleaned out the EGR valve and changed the crankcase breather filter a few times since ownership

I believe they call it maintenance :pac:

maidhc

JohnCleary wrote: »

My 320d doesn't emit any black smoke/soot

Having said that i've just had the turbo re-conned, changed the PC's, cleaned out the EGR valve and changed the crankcase breather filter a few times since ownership

I believe they call it maintenance :pac:

Repair is the technically correct term.

I think it depends on the engne. The toyota diesels seem very clean, whereas some VAGs smoke like a steamboat.

Owen

I know a guy with a 1.4 Diesel MINI, which has the same engine as a Toyota D4D. You'd think he was in a James Bond movie, and after flicking a smoke screen button with the amount of crud that comes out of his exhaust ... recently though, he changed the car's air filter, and diesel particulate filter and it cured the problem for about 6 months.

Matt Simis

Modern diesels emit less smoke compared to the same sized engine 15years ago. However, modern diesels are generally bigger than engines in the past.

Its true VAG stuff has a tendency for more smokey output (1.9TDI and R5 2.5TDI in particular). Mine didnt output much till I got it remapped. I have found however that the combination of Topaz "Clean" diesel and Dipetane fuel additive has made a very significant visible reduction in the smoke output. Running on BioDiesel completely eliminated black smoke when driving but added a lot of white smoke when starting up from cold (carbon buildup being burnt off). Even adding 10% BioDiesel to all our Diesel would be enough to dramatically clean the exhaust output.

Good general maintainence will also help.

mickdw

JohnCleary wrote: »

My 320d doesn't emit any black smoke/soot

Having said that i've just had the turbo re-conned, changed the PC's, cleaned out the EGR valve and changed the crankcase breather filter a few times since ownership

I believe they call it maintenance :pac:

Ive yet to see a 320d that doesnt give out a puff of black smoke on acceleration regardless of whether the car is new, old, mantained or not. You wouldnt see it in the mirror when driving though

JohnCleary

maidhc wrote: »

Repair is the technically correct term.

I think it depends on the engne. The toyota diesels seem very clean, whereas some VAGs smoke like a steamboat.

Granted the turbo shouldn't have needed a re-con but I was glad I did it (wasn't bust but was on it's way out) however the EGR is maintenance - they do get gunked up and the Pressure Converters could have been maintenance (ie. cleaning out the little air filters in them) but decided to replace to be sure

Also it's fair to assume that if you're driving 'easy' for a long time there'll be a build-up of soot in your exhaust, so when you 'thrash' it it'll blow all the sh1te out

snowman707

peanuthead wrote: »

Just wondering if anyone could explain why alot of modern turbo diesels emit quite a lot of black smoke?

Any thoughts?

Bad driving practice, nothing more.

Matt Simis

snowman707 wrote: »

Bad driving practice, nothing more.

Emm, auto boxes?

voxpop

Matt Simis wrote: »

Running on BioDiesel completely eliminated black smoke when driving but added a lot of white smoke when starting up from cold (carbon buildup being burnt off). Even adding 10% BioDiesel to all our Diesel would be enough to dramatically clean the exhaust output.

thought bioDiesel was a no-no with modern diesels ?

gofaster_s13

When you floor the accelerator on a Diesel the ECU/injector pump will automatically switch to excess fuel which will give a momentary shot of black smoke the same thing happens to a lot of turbocharged petrol cars ie evo's imprezas etc when you floor the throttle causing a momentary shot of black smoke as well.

cashmni1

JohnCleary wrote: »

Granted the turbo shouldn't have needed a re-con but I was glad I did it (wasn't bust but was on it's way out) however the EGR is maintenance - they do get gunked up and the Pressure Converters could have been maintenance (ie. cleaning out the little air filters in them) but decided to replace to be sure

Also it's fair to assume that if you're driving 'easy' for a long time there'll be a build-up of soot in your exhaust, so when you 'thrash' it it'll blow all the sh1te out

Thanks JC, I always wondered if I could do this with my car (VAG). Was the job on the EGR and PC's much or did you do it your self?
I went to a VW mechanic friend of mine who disconnected the EGR for a few days to see if this would stop the (not abnormal) black puffs etc, but the ECU threw up an engine light fault so I reconnected it again and frogot about the whole thing.
At what kind of milage should one be doing this maintenence? 100k?
Cheers.

JohnCleary

What I would do (don't take this as gospel):

Remove teh EGR, it's not a hard job. Soak it in petrol/carb cleaner which will loosen up all the crud

Replace your Crankcase Breather Filter (I assume VAG's have these)

Clean your PC filters or replace them like I did (About 50euro each from the UK)

Inspect ALL vacuum lines


Not too sure what type of turbo you have, but my car has a variable vane turbo. Turns out the VNT mechanism that controls the vanes was clogged up hence turbo not boosting properly. Turbo Technics did this when re-conditioning the turbo

fastrac

Is there any way this could be caused by low quality diesel.I know some tourists who had problems with their German diesel cars when they filled up here and were told the fuel here was inferior to the European diesel

peanuthead

snowman707 wrote: »

Bad driving practice, nothing more.

sad

craichoe

fastrac wrote: »

Is there any way this could be caused by low quality diesel.I know some tourists who had problems with their German diesel cars when they filled up here and were told the fuel here was inferior to the European diesel

Don't think theres any difference
Been driving on Conto-Euro diesel for a Year and a half now and no difference.

Driving patterns in Continental Europe are difference, less stop start and more motorway, i only get 400 miles out of a tank now, used to get between 500 and 550.

The French mix in 5% Biodiesel now i believe.

Matt Simis

voxpop wrote: »

thought bioDiesel was a no-no with modern diesels ?

Not on everything, mine has no DPF.