intermittent .. why? exhaust becomes loud like a saxo for a minute... then fine again 2.0 170 CR

[Meemo]

So my car of recent has started doing a strange thing.
2010 2.0TDi 170 CR (104k on the clock)

After a good long drive (50 ish miles) on 4 occasions now the exhaust has suddenly become so loud I hear it over my heavy metal (yes that loud!).
So I turn the music down and it is as if I have had a DPF and EGR delete and no exhaust, the turbo becomes very loud spooling, exhaust very deep sounding and loud, at this point every guy on the road gives me a thumbs up... chill it boys

when i am stationary during one of these moments the engine is now revving steady at 1000rpm rather than the normal 800rpm

It has happened 4 times now and then dissipates to normal after a minute.
Managed to have it happen pulling up at the Krispy Kreme meet last night in Kingston, and being told "wow heard you coming, your car sounds SICK"... well actually, I think it may be sick at this point lol
and a helpful, "nah it is broken, it sounds better therefore is fixed!!" thanks but not helpful

• I have no back boxes and custom pipework to the standard midbox,
• DPF EGR CATS etc are all still there, I havent deleted these currently.
• standard map
• No loss of power during episode
• My car always smells super sickly sweet from the exhuast emisions (only this year that started and since using super diesel), I am told this is a classic diesel cat smell so may have nothing to do with it
• I can feel some vibration/feedback through the peddles when pulling off from standstill when it happens (Clutch?)

Car drives a dream and is serviced twice a year with genuine parts (this is my baby afterall). Runs on Super Diesel 80% of the time.

My only random brain fart on this so far is that during a DPF regen, the exhaust superheats, is it possible this heat is causing a break in the seal since having my custom exhaust done, and then when cooling the seals meeting up fine again?

Or EGR cause any weird symptoms like this?

Anyone else got a brain fart on this one?

 

[matt.russell]

Yep, its when the car is doing a dpf regen.. does it on mine also sounds really really noice

 

[Meemo]

Yep, its when the car is doing a dpf regen.. does it on mine also sounds really really noice

Thanks! I have come to the same conclusion at this point, glad you say that as I feel relieved now Still want deletes though, just not quite so soon!
You have back box's too?

Unfortunately am still losing coolant (very slowly) and it is burning off when the car is on, literally the most sickly sweet smell.

I have seen a small puddle on occasion under my drivers headlight which I only noticed few months back (had this car since 2013 and never seen it before), and this is when I hadnt run the air con a few months so sure it isnt condensation. #

Hopeing it is coolant leaking slowly on to something hot (part of the exhaust maybe) and burning it off. Going to take it to a friends friend at an MOT station on saturday to pop the emissions tester in the top of the coolant bottle to be certain, idea is if it detect carbons (unburnt fuel) then head gasket, if not it is a leak somewhere else and I need to keep an eye on the level till I take the bumper off to look properly.

 

[Paul @ Unit 9 Remaps]

pressurise the coolant system with a leak tester and have alook around for leaks, could also be EGR cooler. very much doubt its head gasket

 

[Meemo]

Thanks "@Paul @ Unit 9 Remaps" and @matt.russell
Paul do you know if the b8 2.0tdi CR has EGR cooling per chance? Some guys the other day said it didnt, however I have a feeling they didnt actually know and just said that because they was curious what I/A GIRL was up to under the bonnet at a car show when checking my oil cap for milkyness (it was fine )...