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Grey Smoke when Idling


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I'm after some advice.  I have an 05 A8 3.0 TDI with around 150K miles on the clock.

 

Recently I have started getting thick grey/white smoke from the exhaust when idling from cold. e.g. if when starting the car I then get stuck in traffic I would get thick smoke that would clear up once I got going out of traffic and then be fine.  I took it to my local independent and they found a fault code with the EGR and replaced this. However, problem still exists.

 

Then today, after a 150 mile trip I got stuck in traffic and the smoke started again, so it is not just when cold like I originally experienced. Again, it cleared once I got driving again.

 

Does anyone have any pointers what the issue could be?  Like I say, it only happens when I'm stuck in traffic and it can engulf the car when really bad. Smoke is very thick grey/white and smells a bit like diesel, chemical so isn't just water based.

 

If anyone has any pointers on what this can be that would be great. It seems quite specific in that it only does it when idling, crawling along.

 

Many thanks for reading.

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If you are getting grey/white smoke that smells like diesel, that is because it is unburnt diesel.

 

Has the cambelt been replaced recently, or turbo, or anything else major?

 

Get a compression test done, get the injectors checked out.

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Yeah, it smells of something, but can't be 100% sure it is diesel.

 

The strange thing is though it is only when I'm idling or crawling that it starts belching out. Does that lead to a certain diagnosis do we thing?

 

No major other stuff done on it lately.  It actually started happening after I had some work done on the front suspension and a new brake caliper due to a leak but not sure if any of those could be related, I put it down to coincidence.

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Thanks all

 

I have had a look around the engine and noticed something.  If you look at the picture below then the large black "box" highlighted red is very loose and I see some screws are missing that are meant to attach it to the car properly.  Also, the square flexi tube thing connecting into that (green box in picture) was not fitted on properly at all, completely hanging off.

 

I've no idea what all that is though.  Could that cause the issue?  Also, is that something they would have had to remove to fit new suspension arms to the front, or when they replaced a rear brake caliper, or when they fitted a new EGR (Exhaust Gas Re circulation) unit? 

 

Car Engine Question

 

 

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That's the air box, it contains the air filter.

If air is getting past the air flow meter, which is the pipe in the top right corner of the red box with a cable coming out of it, then it could cause the problems you describe, if it's simply a loose airbox and all the pipes after the air flow meter are tight, it's probably not the issue, but needs securing anyway.

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Does the car have dpf ?

Is the engine oil overfull and smell of diesel ?

Need to look in to cylinder correction factors with vcds and see if the ecm is correcting for bad injectors .

I think that the air box may of had to be removed for replacement of the upper suspension arms , if the 8 is like some of the other audi models you have drop the upper cradle down a bit to get the suspension arm bolts out , have a look at the air mass ducting to make sure it's secure and not allowing false air ingress .

Check in the turbo boost pipes see if they are heavy with oil , there will be oil residue in the pipes that's normal , take the inlet trunking off the turbo and see how much play is in the turbo shaft .

Just looking back at your post where you say "large black box " ...... if you didn't know that that was the air filter you may struggle a bit with the checks I've said to carry out , find yourself a good independent who knows there stuff

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OK, it has got worse.  My engine light was on this morning and car in limp mode. I have taken it into Audi for analysis and they have said this is down to a blocked intake pipe (to EGR I think) and the boost pressure sensor. That will be around £500 to fix.

 

However...

 

They have then looked at what could be causing the smoking and have said it is the injectors. They have inspected and all need replacing at a cost of around £3,200.  Does this sound about right or could I get it done much cheaper elsewhere?  If that is the cost then I think the car is just going to be sold/scrapped as it's not worth much more than that.  If people think it could be cheaper though then I may go ahead.

 

Is replacing injectors something main dealer would need to do or can any competent mechanic do it for a fraction of the cost?

 

Thanks for any advice...

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Any compentent tech can replace the injectors.

 

Have a quick look on you tube for injector replaceemnt and see what you think.  Have a look on eBay for new injectors too.  They are expensive!!!!

http://www.ebay.co.uk/sch/i.html?_from=R40&_sacat=0&mvsub=1&_mcatda=true&selfil=2%2C3%2C1%2C9%2C8&selvel=Audi%7EA8%7E2005%7E4E_%2520%255B2002-2010%255D%2520Saloon%7E3.0%2520TDI%2520quattro&_nkw=diesel%20injector%20Audi%20A8%202005%204E_%203.0%20TDI%20quattro

 

 

Also, once the injectors are replaced, you need VAG-Com to set them up properly.

 

Not sure if ultrasonic cleaning of the existing injectors would be worth a go?  Obviously, you'd be without the car for a while.

 

 

What fuel do you use?  I ask, because my diesel 8 has nigh on 260K miles, and all is well.  I use Shell fuel for 99% of the time, never supermarket stuff.  I aslo use Miller's Diesel Plus every now and then to keep them clean.

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  • 3 weeks later...

Quick update on this for those that may find this in the future with similar issues. I had the boost pressure sensor replaced and that sorted out the engine light and got things running again. No idea if that was just a random fault or in some way related to the injector issues perhaps sooting things up.

 

Anyhow, for the injectors it turns out you cannot get the Piezo injectors cleaned and they need to be replaced. I found a diesel engine specialist and they have taken the injectors out to manually pressure test them and confirmed they are leaking. They have then replaced all 6 injectors with new injectors, new oil filter and coded the new injectors in for a grand sum of £1,500, so much more reasonable than Audi and a few other garages were quoting. I think key here is to find the right engine specialist that does this day in day out. They are also a Bosche specialist workshop as well so probably got the parts cheaper as even eBay I was struggling to find a set of 6 new ones for less than around £1,200.

 

Hopefully that is the end of the issue but will have to drive it around a bit more to see if the smoke is really cleared up.

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