Excess soot production

[Chri5B]

I've noticed of late that my good ol' tractor sometimes produces a large dose of soot, more than I've noticed in the past

Coming home from Liverpool on Sunday evening, I was trying to reproduce the soot output but I can't consistantly make it happen. Banging through 2nd, 3rd and 4th (to the redline) didn't produce any visible soot. However, at one point a gentle squeeze of the throttle in 3rd (IIRC) from around 1750rpm to no more than 2500rpm left behind a smoke cloud Mr Bond would have been proud of. I reckon the smoke is mainly back but it's hard to tell as I drive away from the cloud. Performance doesn't seem to be down at all and I've been getting 50+ MPG on some long runs over the weekend.

The car's on 73k and is about 2k out of it's 70k service (done by a main dealer). I'm keeping an eye on the oil levels now (daily if I get chance). When I looked tonight I thought there was possibly a smidge too much oil in but my drive isn't totally flat, so it's difficult to be 100% sure. I'll check at work again in the week as the car park is flat.

Anything simple to check? I did wonder if I should have the air filter out for a clean? It didn't get mentioned on the bill from the service so I'm wondering if it's mucky.

TIA,

Chris.

 

[mrcoyote]

I can't remember if the air filters are changed every 20k or 40k, so you wouldn't have had yours changed at 70k. It might be worth pulling it out and checking the state of it though.

Can't comment on the soot though.

 

[Nath.]

diesels always make a bit of smoke when on full throttle in the torque band (1500 to 2500 ish revs)

cheap supermarket diesel makes a but more smoke than the quality stuff too

 

[Chri5B]

diesels always make a bit of smoke when on full throttle in the torque band (1500 to 2500 ish revs)

cheap supermarket diesel makes a but more smoke than the quality stuff too

The worst smoke was on part throttle, I was far from foot to the boards.

In the past twelve months, the car has had one tank of BP Ultimate but otherwise it's purely been Shell Derv.

 

[EdButler]

Mine only ever really does it when youve not been ragging it for a few minutes. It seems that they slightly over fuel when the turbo is initially spooling from low rpms (like nailing it from 1500) - requested boost is high and actual boost is increasing. This injects more fuel to try to get the turbo spinning faster but theres not enough air for clean combustion.

You probably wont see much once you get going because all the boost levels etc. are nominal. I noticed this at Santa Pod a few weeks ago - At the lights and Wooosh, loadsa soot, then nothing at all really.

If its really bad however, some VAG COM logging might not go amiss as the turbo vanes or something along the line may be on thrie way out.

 

[markmck]

does the egr not cut off on full throttle but is active on part?

 

[sssstew]

yes correct Mark.

and service intervals for air filters is 40k by the book, but i do every 20k.

 

[cheshire cat]

I guess they're waiting for 80 K to fit a new filter, nothing like going by the book, so in reality it's well past it's sell date, I recon your egr could do with a decoke too, that won't be in a service either, take a look with a torch

 

[Chri5B]

De-coke my what?

Airbox and the filter inside I can cope with. EGR you'll need to point me in the right direction!

 

[muddyboots]

Reckon airfilter is a good bet, will be completely clogged after 30k.

Why not get a Green filter seeing as your warranty is but a distant memory

Mine used to behave exactly as Ed described. In a higher gear, if you booted it while off boost, it would smoke quite noticeably just as the turbo was about to spin up. Once spinning and the car was away, no more smoke.
If you're clever you can deliberately induce this phenomena if there's someone annoying you behind without actually gaining speed

 

[DIFT]

If you're clever you can deliberately induce this phenomena if there's someone annoying you behind without actually gaining speed

I cant condone this action but its sooooo much fun, especially post remap.

 

[Chri5B]

Will look into a green filter, although that must be verging on a mod and therefore an increase in insurance.

Good to know you experienced the same at higher miles Lee. The oil seals went in the turbo on my Scooby and that cost me a bit to sort out so I was (am) a bit nervous

 

[muddyboots]

Wasn't just at higher miles - it always did it !

I didn't notice any deterioration in performance / smokiness / economy at all even after 79k when it went to it's new home.

If it was just a one-off, maybe it was just the VNT mechanism sticking briefly causing it to underboost (hence the smoke), or rogue signals from a sensor.

 

[muddyboots]

I cant condone this action but its sooooo much fun, especially post remap.

LOL, I know. Must get the Passat done soon

 

[Trumpetman21]

Don't think it means owt bad - I'd be worried if a derv didn't smoke!

 

[nickibizaCUPRA]

ello chap, when i have pdi'd new passats, golf 2.0tdi's, altea's, new leons and mk4 ibizas they have done that too, and i know what you mean its a BIG cloud of smoke!!! wouldnt worry too much, checking air, and or diesel filters wouldnt do any harm (diesel filters are every 40k as with the air flters) hope this eases your mind slightly lol

 

[Triple D]

Mine doesnt have an EGR valve, could that be why it smoke a bit more than normal?

 

[Chri5B]

Wasn't just at higher miles - it always did it !

I didn't notice any deterioration in performance / smokiness / economy at all even after 79k when it went to it's new home.

If it was just a one-off, maybe it was just the VNT mechanism sticking briefly causing it to underboost (hence the smoke), or rogue signals from a sensor.

My Mum followed me once and mentioned the soot output I left behind and that was probably 20 to 30k miles ago. Maybe I've just happened to notice it more now?

Will check the few things over and keep a close eye on the oil levels.

Thanks folks.

 

[muddyboots]

Mine doesnt have an EGR valve, could that be why it smoke a bit more than normal?

No, not having an EGR should - if anything - cause less smoke, as you're always sucking 100% fresh air in, instead of any exhaust gas being recycled.

But as EGR only operates at idle or very light throttle I doubt it would make any difference to smoke.

 

[cheshire cat]

the EGR is the thing with the round shinny to fixed to the manifold, remove the rubber elbow, carefull with the spring clips, and take a look inside with a torch or test with a finger for coke sludge and crud, you are looking for a reduction in cross section best of luck