Fumes from EGR area

[gazd21]

Hello

I am new to the forum. Love my C7 A6 Avant but it has suffered from an issue for about the last year where every few trips a horrible strong smell of rich exhaust fumes comes through into the cabin through the vents. Have noticed that fumes are coming from the engine bay when this happens. Have managed to 'catch' it and get the following videos of an obvious leak around the EGR area:

1 - Audi CGLC exhaust leak at EGR? - YouTube (https://www.youtube.com/watch?v=R3ValaTAAzA)

2 - Audi CGLC exhaust leak at EGR? 2 - YouTube (https://www.youtube.com/watch?v=BFeqiZ-JzGg)

This happens for a little while then completely goes away. It then starts doing it again after a few journeys. All I can think of is that it must be to do with a DPF re-gen as it would do it constantly if it wasn't to do with something that doesn't always happen.

A bit of extra information is that the seller of the car informed me that it had a 'stage 1 remap', am getting no warning lights on the dash, when the issue happens the engine fan stays on after the ignition is turned off, and the engine is the CGLC 2.0TDi.

Any help with this would be much appreciated. I would like to find somewhere that could fix the issue for me but I want to narrow it down as much as possible so that the minimum of diagnosis has to be carried out.

Many Thanks

Gareth
gazd21

[nordic_b]

Hi

With remaps it is hard to diagnose problems.

The amount of smoke looks a little too much for the EGR to be at fault. It looks like exhaust is venting everything outside. I'd check how turbo to downpipe joint looks like, there is a metal gasket that may have perished due to restrictions in the exhaust system?

[gazd21]

Hi

Many thanks for your reply. I will check the area you have suggested. The thing I can't figure out is that it only does this for short while (around 10 minutes every few journeys) and then it will completely go away? The exhaust doesn't make any strange noises either?? This would suggest that the main exhaust system must be ok and that the issue would lie in something that was temporary (like the EGR being active). If I took it to a re-mapper, do you think they would be able to see what changes had been made to the standard map? I'm more than happy to have to put back to standard.

[MFGF]

Hi

Many thanks for your reply. I will check the area you have suggested. The thing I can't figure out is that it only does this for short while (around 10 minutes every few journeys) and then it will completely go away? The exhaust doesn't make any strange noises either?? This would suggest that the main exhaust system must be ok and that the issue would lie in something that was temporary (like the EGR being active). If I took it to a re-mapper, do you think they would be able to see what changes had been made to the standard map? I'm more than happy to have to put back to standard.

Are you sure it's not just regenerating the DPF? It generates a lot of heat to burn off the soot in the DPF, and often the fans run on after the car has been switched off. What you're describing - around 10 minutes every few journeys - sounds like it might be normal. Is it possible you have a small oil leak and it's just burning off during a regen?

Just a thought.

MF.

[nordic_b]

It is hard to explain tbh, there should be no smoke under the bonnet in any case, so something has ruptured and letting the fumes out. I can see in the video it only comes out on some load when turbo builds pressure. It is not uncommon for the egr to exhaust metal pipe to split, but it is still hard to explain that amount of smoke.
I don't think regen runs while idling or standing still, unless forced by diagnostic software. Have it looked by someone, it doesn't look right.

Remaps make engines run outside stock parameters that only the tuner may know about. It can also disable fault reporting, and what not..

[gazd21]

It definitely sounds like it is DPF related, but I don't think it is oil burning off as there is a constant flow of fumes that increases with throttle when it is happening. Does the flow of exhaust get altered when a DPF regen is in process?

[gazd21]

Thank you for having a look for me. I will check all of the pipework when I get a chance in some daylight. I've only had the issue start whilst driving. Would a regen that started whilst driving continue when the car was then parked but the engine left running? This is how I managed to get the video. Discovered it was happening on a journey when I was nearly home so I managed to get the bonnet up and film the fumes coming out over the DPF and EGR area. There must definitely be a hole somewhere for it to get out of. I just can't fathom how it doesn't do it at all for the majority of the time ��*♂️


It is hard to explain tbh, there should be no smoke under the bonnet in any case, so something has ruptured and letting the fumes out. I can see in the video it only comes out on some load when turbo builds pressure. It is not uncommon for the egr to exhaust metal pipe to split, but it is still hard to explain that amount of smoke.
I don't think regen runs while idling or standing still, unless forced by diagnostic software. Have it looked by someone, it doesn't look right.

Remaps make engines run outside stock parameters that only the tuner may know about. It can also disable fault reporting, and what not..

[johnsimcox]

Thank you for having a look for me. I will check all of the pipework when I get a chance in some daylight. I've only had the issue start whilst driving. Would a regen that started whilst driving continue when the car was then parked but the engine left running? This is how I managed to get the video. Discovered it was happening on a journey when I was nearly home so I managed to get the bonnet up and film the fumes coming out over the DPF and EGR area. There must definitely be a hole somewhere for it to get out of. I just can't fathom how it doesn't do it at all for the majority of the time ��*♂️
Yes the regen will continue after you have stopped driving. Usually accompanied by an acrid smell outside the car and the cooling fan continuing to run after the engine is switched off

[nordic_b]

I hope that's right, but DPF regen needs very high exhaust temps, something tells me it is impossible to continue regen at idle. Even when forced, it runs at higher idle. If the idle is below 1K, I think regen is not happening.
Egr, on other hand, opens up on idle, closes on load/boost, and in semi open state while driving.

[gazd21]

Hi. Thanks to everyone who replied to my original post. I thought I would come back to post the solution to the issue. Turns out that there was a crack around the seam of the DPF pipe. Unfortunately the engine had to be dropped to access this to have it welded up ££££ 😩. Also had the EGR replaced at the same time ££££ 😩. Also the Multitronic oil was due £££ 😕 all after having all the discs and pads replaced at the last MOT £££ 🙉 and the (large, start/stop) battery replaced not long before £££ 💸.

So it’s been a very expensive couple of months but the issue is fixed and the car runs like a dream and will hopefully be in shape for many more miles to come (currently at 142k) as I’m definitely not selling it after spending all this on it! 😅

All the best Audi fans.

gazd21