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Burning Smell coming from Exhaust after Decarb Service

prplatano

New member
This is my first post, so I will try to make it easy to understand.

I am the first and only owner of a beautiful candy white 2010 GTI. About two months ago I started getting a very rough idle and the car was misfiring, about a day later I got the dreaded CEL. It was to the point the car would shake vigorously and seemed like it would stall but never did. I didn’t have a choice at the time, so I had to take it to my friendly neighborhood VW stealer ship. I was also fast approaching my 80K service, so I tacked on the DSG fluid and filter change with them as well.

They had the car for like two days, and found out a few things. It was like 2 months ago, so I might be missing a few details. They found a bad intake manifold, this had an extended warranty covered by VW, so I was lucky. The service technician recommended I get a decarb service as well since they were already in there and would not charge for the labor to get in there. (She mentioned the CEL could come back if I didn’t do this) I reluctantly said yes. There was also a leaking valve cover gasket and a crankcase breather valve I would have to pay to get replaced. I just wanted my car back and said OK to everything. After picking up my car it drove like the very first day all over again.

During the same week I thought it would be a good idea to just do everything else that was left for the 80K service. I have a friend that likes to do this kind of stuff, so we took care of the Oil and filter change and also replaced the fuel filter.

About a week later I started smelling a foul smell coming from somewhere. At first, I didn’t even realize it was from the car. It smelled like something was burning. After a few occasions of me smelling around my car I finally located the source. It was coming from the exhaust. It was horrible, I called the dealership to let them know and was told this was normal after the decarb service. She said if it continued for another week or so to bring it in. So of course, it continued for like 2 weeks and I had no choice but to bring it in again. After a few hours they said they found a bit of fluid on the engine bay and cleaned it up. They couldn’t find anything else and said it might still be the decarb process burning off some leftovers. They said to drive it for another few weeks and return in a month if it’s not gone by then. Of course, it’s now a month and the smells are just as bad.

I am now worried about going to the dealer again, is there any chance this could have been me and my buddy changing the fuel filter? I don’t want that to be the case and then get charged another arm and a leg because of all the technical checks they’ve had to do. Any help here would be greatly appreciated, and I am so very sorry for the long post.

TLDR: My car smells bad!
 

Tyler12108

Go Kart Newbie
Sounds like their recommendations were spot on for the services on your car with that mileage, definitely a strange issue though.
 

Boscogn

Go Kart Champion
I would also change spark plugs. If that hasn't been done recently. Bad smell though is weird all the items they recommended seem spot on so don't feel like u got service you didn't need. I'd try to Italian tune up at least once a day. Drive for 20min at 4k+ rpm hopefully u burn up whatever is causing the smell. I had an old Lincoln that had an oil leak that dripped on the exhaust manifold making an awful smell. I'd just test for any leaks. Hard to say what it could be.

Edit: not ur fuel filter that would just smell like gas.

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prplatano

New member
I appreciate the input, although i probably should have mentioned that I have driven the car a good 1,500 miles since all the work was done. I had a feeling it might have something to do with the decarb services because all the gunk they cleaned off may be whats still burning off, but like i mentioned before it should have dissipated by now. It is so bad sometimes I have to put the windows up at a red light. I also feel pretty bad for the people behind me. lol
 

Boscogn

Go Kart Champion
I appreciate the input, although i probably should have mentioned that I have driven the car a good 1,500 miles since all the work was done. I had a feeling it might have something to do with the decarb services because all the gunk they cleaned off may be whats still burning off, but like i mentioned before it should have dissipated by now. It is so bad sometimes I have to put the windows up at a red light. I also feel pretty bad for the people behind me. lol
The valve head gasket is a liquid seal if they went ham on it possibly that burning is causing the smell. If they didn't vaccum all the gunk any left over would smell while it's burning. Also oil smells like crap when it burns. It's really hard to tell what it could be. I'd drive it for 3500 miles more untill ur next oil change and see if it doesn't go away. If they left crap in the intake manifold they'd have to get on there and vaccum it out. Also I hope they closed the valves while doing the cleaning. Anyways I think after 5k miles you'd have more ground to stand on for them to take a better look. Also adding uv dye to ur oil and drive it for a few days then take a uv light and look for leaks.

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lilonespaz

Drag Race Newbie
hmm that's strange. Im completely cat-less and besides a wif of exhaust fumes every now and again at a red light or when i turn her on in (with windows down) its not that bad.

Are you burning oil?
 

Carlosfandang0

Autocross Newbie
You say it’s a foul smell right but what would you compare it to?? Is it a sulphur/egg smell? Maybe bad fuel! But I see you’ve probably used several tanks by now.


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Last edited:

prplatano

New member
hmm that's strange. Im completely cat-less and besides a wif of exhaust fumes every now and again at a red light or when i turn her on in (with windows down) its not that bad.

Are you burning oil?

lilonespaz, That is something I didn't even think to check. I will start checking the dipstick level tomorrow.
 

prplatano

New member
You say it’s a foul smell right but what would you compare it to?? Is it a sulphur/egg smell? Maybe bad fuel! But I see you’ve probably used several tanks by now.


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Carlosfandango, I though it was bad gas at first too. I have been going to a different station since then just to scratch that off the list. If i had to describe it i would say burning toast, like really burned up toast not the one you can still eat. The smell is so bad that i notice it at red lights and have to put my windows up or start getting dizzy. Like i said before i feel really bad for the people behind me.
 

lilonespaz

Drag Race Newbie
you sure you dont have a exhaust leak? or like a hole in your exhaust?
 

slowgti08

Ready to race!
Had this after my service, looked under to find a plastic bag being burnt by the exhaust.


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prplatano

New member
Just wanted to follow up and let you guys know that the smell finally went away about 2 weeks ago. So in total I had to drive the car about 3k after the service for the smell to go away. I just wish the VW dealership would have told me about this instead of letting me worry this whole time. Thanks for your help everyone and happy holidays! :)
 
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