The great big technically challenging international XUD turdo smoke machine

[castros_bro]

The Brasilian/Portuguese word  "bomba" is feminine and has two (or more) meanings  so this is a thread about oily motors French with injector éclairs*.  Smoke (and other VAG pollutants) and now classed as BAD so have condemned my newly acquired Pug 306 tubot XUD to the "shed of non-MOT shame" to await fettling.  I realise there is a vast diesel knowledge and Junkman here who may have some pointers as to what may be causing the excess smoke and what can be tried to reduce it to the new MOT acceptable levels.  I do not know the colour of the smoke and did not notice anything particular/particulate wafting behind when driving notr when sitting in a garage blipping throttle.  The next and easy step for me is change air filter, fuel filter, oil filer and oil (as I have these already) and a bottle of snake oil/ injector clean in a little diesel.  What other HELPFULL suggestions are available to the cheapskate motorist?

 

 

 

* bomba = pump or bomb or éclair

 

 

 

[sierraman]

Chuck some ‘stop smoke’ stuff in if the filters are ok. Then get it absolutely roasting before you resubmit it.

[Lacquer Peel]

Italian tune up. Is it running cool?

 

As far as I can work out the new diesel emissions rules don't affect pre-DPF cars.

[rainagain]

If it has a Bosch pump fill with a veg oil/diesel mix, you don't get any smoke from veg oil

 

for example:

 

https://igmaynard.co.uk/bongo/forum/viewtopic.php?t=16431

 

smartmonkey » Wed Nov 21, 2007 12:42 pm

Its very rare a diesel will fail on veggie oil. It normally drops the emissions right down to nothing

[Lacquer Peel]

 

If it has a Bosch pump fill with a veg oil/diesel mix, you don't get any smoke from veg oil

 

 

 

Yes you do

[Guest Hooli]

 

If it has a Bosch pump fill with a veg oil/diesel mix, you don't get any smoke from veg oil

 

for example:

 

https://igmaynard.co.uk/bongo/forum/viewtopic.php?t=16431

 

smartmonkey » Wed Nov 21, 2007 12:42 pm

Its very rare a diesel will fail on veggie oil. It normally drops the emissions right down to nothing

 

 

Bah, they can smoke like a tank on that stuff.

[Andyrew]

I've found a dolop of mineral 2 stroke in the tank has made my disco quieter and helped hugely with it's smoke problem.

[D Spares & Tyres]

Cannot help without knowing the colour of the smoke

[Scruffy Bodger]

First thing would be take it out for a run and thrash the shit out of it. If you've been trundling round the exhaust will be full of carbon that'll come straight out the exhaust when they rev it up to test. I'm assuming it was tested fully up to temp and not left there and they tested it from cold.

If it's grey smoking at cold start this could be a leaking injector, dodgy glow plug or even the pump timing being slightly out. I've had a 306 from a mate that used to fill the street on startup sometimes, advancing the pump sorted this completely.

As Mr D Spares says it's difficult to help unless knowing the colour of the smoke. He knows a bit about these things, I've followed one of his cars in the past and seen the smoke have various tinges of purple to it, like something out of a Harry Potter movie.

[rainagain]

 

Yes you do

 

Sorry I should say a lot less:

 

3.9. Effect of waste cooking-oil biodiesel blends on smoke opacity

Variation of waste cooking-oil emissions for different biodiesel blends with respect to engine load are shown in Fig. 10. Smoke emission increased with engine power output for all fuels. The increased trend of emissions is due to the increase of fuel consumption with engine output power. Presence of branched and ring structures in diesel fuel increases the emission levels. Smoke emissions of biodiesel blends were lower than diesel fuel under similar operating conditions. This inbuilt oxygen in biodiesel blends led to better combustion and smoke emission reduction. Smoke emission decreased with increase in biodiesel percentage in biodiesel blends.

https://www.sciencedirect.com/science/article/pii/S111006211830014X#f0005

 

 

[castros_bro]

Bit more info,

 

I had owned the 306 for a couple of hours before the MOT and it was carefully* driven on private "Italian" motorways for 140 miles to the MOT so it got hot. I do not know the colour of the smoke but assume it was probably black if the emissions were  significantly in excessive of the specified limit

 

The idea of putting fuel with less carbon density sounds a bit experimental but possibly covers the "too much fuel" option. 

[Scruffy Bodger]

Is it a Bosch pump? If so it should be clear to see if the anti tamper fitting has been removed and someone has "tuned" it. If it's a Lucas it could still have been altered but you can't really tell by just looking at it.

Someone also may have altered the lda, the UFO shaped thing on the top of a Bosch pump.

[castros_bro]

'Tis a Bosch pump, will go check later if seals and max speed paint is disturbed.

[Scruffy Bodger]

That's a proper bonus. Maybe just fudge it through the MOT then?

 

My mate owns that, it's circa 237bhp & 327 ft/lbs, it smokes a bit on boost as you might imagine. He simply adjusts the maximum fuel screw on the side of the pump to get it through the test leaning it right out. It won't hurt the engine, too much fuel is what damages dervs.

[Matty]

That's a proper bonus. Maybe just fudge it through the MOT then?

 

My mate owns that, it's circa 237bhp & 327 ft/lbs, it smokes a bit on boost as you might imagine. He simply adjusts the maximum fuel screw on the side of the pump to get it through the test leaning it right out. It won't hurt the engine, too much fuel is what damages dervs.

In love

[beko1987]

My xantia had to me massively de tuned to pass the smoke test, I can also confirm that neat veg smokes like a twat if the pumps been fiddled with. You could also turn the fuel screw in (or out, I can't remember) to weaken the mix, limp it to the test with no power, pass then put it back...

 

Just foot to the floor it to test, I got a proper black mushroom cloud out of the back before arthur_foxhake twiddled it

[Guest Hooli]

It's out for less power if memory serves from tweaking a Tdi Landy years ago.

[Scruffy Bodger]

In love

 

Quaife ATB, forged H section rods, blue printed, head ported and flowed with flow bench results to prove gains, Dieselmeken Pump, paddle clutch etc, You are not alone. 

 

Hooli is indeed correct if yo want to lean it out. https://www.306oc.co.uk/forum/printthread.php?tid=145

[dieselassist]

Bosch pump will have the fuel screw on r/h (as you look at it with bonnet open) lower of the pump; below the LDA (space ship looking top bit of the pump) - - locking 13mm nut on the screw; can be wound back out using a butty flat screwdriver at the end; back out in 1/4 or 1/3 turns (otherwise the pump might start pissing out diesel outta various gaskets) n test drive for reduction in shmoke  - repeat till shmoke drops off to acceptable levels...

[MrParody]

I noticed 'fear of failing the MOT smoke test with an old diesel' came up in debate in another thread, so to revive an old topic.... 

 

My recipe for passing the smoke test is:

A 50:50 ratio mix of diesel to biodiesel (not vegetable oil) in the fuel tank.    I usually run the level of diesel in the tank down to circa 5 litres of diesel then add 5 litres of biodiesel.    Then drive about 5 miles, in 2nd or 3rd gear at wide open throttle; to get the mix into the filter and injectors; to clear out any soot in the exhaust and to arrive at the Test Centre in a car with a hot engine.    

 

Try it and see.    Its a winner.   I once got a smoke test result on a 15 year old diesel Passat that was better than what was specified for the car when it was new.