Why would a TDI smoke under load?

[Cyrix]

I've noticed now the nights are getting darker that when I accelerate I seem to generate a large cloud of smoke.

The car is a PD170 that otherwise seem to run good. The car still has it's DPF which is why I ask the question.

I assume this isn't normal and something must be amiss somewhere?

 

[SDHA4SLine]

Have you seen this in the daytime, what colour smoke?

 

[Cyrix]

Light Grey, I've not seen it in the day but people that have followed me have mentioned it. The rear windows are factory tinted so it isn't that easy to see.

 

[SDHA4SLine]

I've the same, but its periodic so assuming its just dpf re gen causing it.

Do you do plenty of long trips down the motorway? I could just be a build up of crud getting cleared out. I would assume its just a diesel thing not sure I've ever seen a diesel older than 4 years not puff out some smoke when booted.

Are you using any additives in your fuel?

Suppose if your handy with spanners you could start with the simple stuff like, remove egr and give it a good clean to see if that helps?

From what I understand...
white smoke = steam maybe condensation build up or worse, leaking/porous head.
blue smoke = oil burning maybe worn turbo seals or something like injector seals leaking
black/grey = usual crud from older diesel lump! or too much fuel being burnt (black smoke)

 

[Cyrix]

I do next to zero motorway driving, my commute is a 25 mile A-road drive through the country, without incriminating myself too much I do like to stretch it's legs a little.

No additives, I replaced the complete EGR due to failure about 6 months ago. As I it runs pretty well without all the usual coughs and farts that plague the PD170 which is why the smoke is a bit odd.

It could be a passive regen but usually you can tell when the car is doing this as the throttle response is a bit slow.

 

[SDHA4SLine]

Doesn't sound like you're too worried. seems as the car is running fine I would just forget about it unless you notice oil or water levels dropping fast or car starts to run rough.

I'm sure you've heard it before but it really is important that our dirty diesels get a good long run once a week, I'm lucky my route to work is a 30 mile motorway trip which (hopefully) keeps my dpf etc clean

 

[csm]

Your cars just needing a good blast on the motorway, go for a wee jaunt and give it the message.

 

[carl-1968]

20 minutes or so at 2-3k rpm to ensure it's give plenty of time to blow it's tubes out!, A lot of inner city cars are suffering DPF failures as they never get the chance to do a full regeneration and end up at the dealers plugged in to do a static regen. Deleted mine so after buying so never had this issue.

 

[SDHA4SLine]

Now I'm paranoid about mine

Spent most of my motorway journey looking in my mirrors to see clouds of smoke in my rear view mirror every time I booted it until 20 mins down the road when it was just down to a little puff of smoke.

Like I say 70 mile round motorway trip each day Monday to Friday and once every two weeks on way to work stick on cruise control at 3k revs for 15 miles on m6.

Only suspect thing I know of on mine is turbo has very slight play left to right non front to back. Could I need new turbo even though my smoke isn't blue haze? I'm not seeing oil or water levels going down.

Dag nam it, wish I never looked now

 

[sidibear]

What fuel are you using? Supermarket fuel used to do that to mine, I just full up at Shell now and have no problems.

 

[SDHA4SLine]

Only owned the car since July so cant vouch for previous owner(s) but I've only ever use shell v nitro diesel or what ever its called

 

[GoneSouth]

Could be overfuelling due to something as simple as a dirty air filter or MAF sensor in need of cleaning.

Ditto comments on supermarket fuel - can make em smoke like chimneys and clog up egr systems etc.

Bottom line is always give your tdi regular long runs to keep the inards clean. Short runs are a killer.

.

 

[SDHA4SLine]

Seems like I'm hijacking this thread, but hope this helps get answers to help Cyrix also.

As previously said I wish I never commented on this thread as I wouldn't be looking in my rear view mirror for smoke from my car!!!

Now that I see there is I'm getting more paranoid every day, I noticed this morning that mine does smoke under load but only when revs get above around 3k nothing lower down. I assume this is when the turbo starts to work hard? (these symptoms were constant for a 35 mile motorway trip this morning)

My car does get good runs 5 days a week to work and back & I'm not shy with my right foot. The car's been thrashed the last 4 days hoping to clear this out but its just not getting better.

I have been toying with getting the turbo replaced but was told by an indy that it has slight shaft play left to right but none front to back, they said this is nothing to worry about?

Do my symptoms give anyone any ideas?

Cyrix, is this the same symptoms as yours?

 

[Cyrix]

Yes the same as mine, fair bit of smoke at high RPM. Drives fine otherwise.

There is a bit of turbo noise when backing off the throttle at low rpm, I suspect one of the vacuum solenoids is a bit sticky and needs replacing as the turbo actuator itself moves freely when I tested it with a Mityvac. Don't really think this is related to be honest though.

I have wondered if it is a slight boost leak, though there are no signs of leakage, performing a smoke test on the intercooler pipework is next on my list.

 

[SDHA4SLine]

I was thinking of changing the tandem fuel pump gasket in case its leaking (heard this can cause smoking issues). Can anyone advise if its just a case of unbolting it stick new gasket on and torque back up or is it a bit more complicated than that?

Worth a try for a few pounds on new gasket...

 

[joinerman]

Drive any oil burner at night & look in the mirror, you will see smoke in the lights of the car behind, it's just normal.

 

[SDHA4SLine]

That may explain why I saw nothing this afternoon when I left work. I finish at 1 on Friday. confused dot com

 

[joinerman]

Boot any diesel a bit & your going to get a grey/brown haze behind, it's normal, if it's black then that's unburnt fuel & needs looking into.

 

[SDHA4SLine]

I know it's a different beast but my old car was 1.6hdi Peugeot had absolutely no smoke that I ever noticed. Had it 3 years 65k miles

 

[SDHA4SLine]

I will take your word for it though as you made me feel a bit better

 

[A4_MaJiK]

Quite normal for a diesel to smoke a little under load. It's the soot that builds up in the exhaust getting blown out. The reason your Peugeot never used to smoke is because it had a DPF (Diesel Particulate Filter) fitted which used to capture all the soot and burn it off when exhaust temperatures were high enough. This is why if you look down the exhaust of any new diesel it will be soot free as the DPF captures it all.

 

[SDHA4SLine]

Mine has a DPF

 

[A4_MaJiK]

Mine has a DPF

Just because it is the TDV variant, doesn't mean it has a DPF fitted. I thought the same with mine until I noticed the smoke just as you did. If it does has a DPF it has either been gutted or has a hole going through it as DPFs stop any soot from coming through. I'm 99% sure you DO NOT have a DPF.

 

[SDHA4SLine]

Someone's told me this before but what's the TDV again?

Mines a 2.0TDI, unless I'm going crazy I can see the dpf clearly in the engine bay it looks exactly like the spare one in my garage that's ready to be gutted when I get it mapped.

 

[Cyrix]

I'm 99% sure A4_MaJiK is talking ********. Both our cars are fitted with a DPF filter.

 

[A4_MaJiK]

I'm 99% sure A4_MaJiK is talking ********. Both our cars are fitted with a DPF filter.

Don't mistake a catalyst for a DPF. DPF would mean you have no soot coming out from the back at all! Mine even has the "DPF preperation" option code in the boot sticker and I know it's not there as I've had a custom exhaust fitted and replaced the second cat with a straight pipe.

 

[desertstorm]

My car had a DPF originally and there was no black soot in the tailpipe at all after 80K miles.
If the DPF is working correctly then you will get no soot. Doesn't mean you won't see vapour coming from the exhaust when the DPF is regenerating or when the car is cold and the water vapour condenses in the cold exhaust.
Inside the rear box, still as shiny as the day it came from the factory.




As for play in a turbo, even a brand new turbo has a certain amount of lateral side to side movement if it uses a Hydrostatic journal bearing which most do. It's only when oil pressure is applied that the "play" dissapears. The oil film is what fills the gap.
Different if you have a ball bearing turbo as they have no lateral movement.
If you can't see anything in the day don't worry about it.

 

[SDHA4SLine]

Don't mistake a catalyst for a DPF. DPF would mean you have no soot coming out from the back at all! Mine even has the "DPF preperation" option code in the boot sticker and I know it's not there as I've had a custom exhaust fitted and replaced the second cat with a straight pipe.

Well I've been stitched up then, this is what I have under my bonnet attached to the exhaust side of my turbo ( this is the one I bought to gut for remap).

This was sold to me as a aftermarket dpf ref audi part number 8e0 254 750 fx. I just checked that part number on the part fixed to car which looks suspiciously identical to this.

Also I was given the same part number by local audi dealer when I asked for the "dpf" part number ( I am able to get part numbers from one dealer now, long story ) and gave them my registration number.

On last audi dealer service I asked them to force re gen of "dpf" they told me it wasn't needed as it showing as only 30%.

Last independent to look at car also noted that he was surprised the "dpf" was in such good condition as he see's lots of issues on 170 s with regards to dpf.

The guy who did my terra clean said after the treatment "I've done you a forced re gen of your dpf mate just for good measure"

If you google the part number above all you get is dpf. I hope I'm wrong here as that means happy days as far as remapping mot/insurance worries after re map.

If anyone has access to etka to check what this part number comes up as I would like to know because if it ain't a dpf then some mechanics have some explaining to do!!!

 

[desertstorm]

That is a DPF checking the part numbers. The fact it has so many holes for Lambda /EGT sensors and the pressure pipes front and rear so the pressure drop across the DPF can be measured is a real good give away.

Karl.

 

[A4_MaJiK]

Picture and part number indicate that is definitely a DPF. Although yours sounds as though it is broken if it is letting soot through as well as the fact the pressure differential sensor only shows 30%. DPFs are designed to block soot as you can see from desertstorm's pics. If it is broken internally, it might find it difficult to get high enough temperatures to burn off the soot. You may also find turbo spool noise more noticeable.

As mine is a 3.0TDI, due to the size and layout of the engine; The DPF comes under the vehicle and not on the downpipe as yours does.