Flaming!? is it safe?

Gaz · 23-03-09, 02:03 AM

It seems according to my m8s following me at the weekend that my cars exhaust flames!

Cool as it is.. Should I be worried? Is there any chance I could blow a big hole in my system?

I'm guessing its doing it because of the missing cylinder at low rpm..

Its like a gun going off when it pops! I heard a girl even scream when it happened last night as i drove thru town past some fittys! lol

Daveymaclad · 23-03-09, 07:23 AM

My very first CQ did that, bubbled a lot and I only realised it flamed when a friend of mine was following me! Mine was caused by a shitty replacement exhaust from the devil (euro car parts). In my experience, aside from some shocking fuel economy (due to the amount of unspent fuel you're forcing through the system) I don't think it's immediately worried!

However I'm not sure how your local constabulary will think of it if they see it, or your MOT test station when that time comes!

Isimmo · 23-03-09, 08:26 AM

As stated really, don't think it's too much off an issue as the 'flame' only really gets going beyond the tailpipe as more air becomes available. Our Ur belches flame so big sometimes you can see it in the rear view mirror, over the top of the bootlid spoiler. And I'm not making that up, there's several people on the quattroforum that have witnessed it. The exhaust has never been damaged, and neither has any rear trim. It's quite rare for a standard KV to get angry, but you're running something a little bit more 'special' so, even when running right, you might get a bit of bad behaviour like that.

Gaz · 23-03-09, 08:44 PM

Quote:

Originally Posted by Daveymaclad

My very first CQ did that, bubbled a lot and I only realised it flamed when a friend of mine was following me! Mine was caused by a shitty replacement exhaust from the devil (euro car parts). In my experience, aside from some shocking fuel economy (due to the amount of unspent fuel you're forcing through the system) I don't think it's immediately worried!

However I'm not sure how your local constabulary will think of it if they see it, or your MOT test station when that time comes!

burbles and flames??? sounds like a good exhaust to me! lol

As for the fuel economy at the moment while missing a cylinder.. CHRIST!... its really bad.

its Lucky I work at a petrol station, or i might not get home after my shift!

Booty · 23-03-09, 10:01 PM

Because you are running what is effectively mechanical fuel injection and the engine has no knock sensors controlled by an ECU, the cylinder keeps fueling and as it's not getting ingnited goes straight down the exhaust. Then becuase of the hot exhaust and highly flammable gasses, voila.....flames. You can of course 'help it along a bit' but me and Simmo will tell you how another day. You do need to get it fixed though as some of the fuel may wash the bores a tad if your rings are worn slightly

Gaz · 24-03-09, 12:27 AM

Quote:

Originally Posted by Booty

Because you are running what is effectively mechanical fuel injection and the engine has no knock sensors controlled by an ECU, the cylinder keeps fueling and as it's not getting ingnited goes straight down the exhaust. Then becuase of the hot exhaust and highly flammable gasses, voila.....flames. You can of course 'help it along a bit' but me and Simmo will tell you how another day. You do need to get it fixed though as some of the fuel may wash the bores a tad if your rings are worn slightly

When you say 'wash the bores' what do u mean?

Is that bad?

Alfashark · 24-03-09, 05:49 AM

Bad indeed mate, unburnt fuel is a great degreaser.... as such it can wash off the thin film of oil spread over the cylinder bores by the rings every time the piston moves up and down... metal on metal = scratched bores/damaged rings.

86audicoupe · 24-03-09, 08:54 AM

I get a lot of backfire and flames but this is through the side exit. Suppose it's a bit different though as the car is running fine but there's unburnt fuel/different back pressure when running with no silencers.

Booty · 24-03-09, 09:57 AM

Quote:

Originally Posted by 86audicoupe

I get a lot of backfire and flames but this is through the side exit. Suppose it's a bit different though as the car is running fine but there's unburnt fuel/different back pressure when running with no silencers.

And with a fully 'boxed' exhaust system the whole little cacophony and vollys of bangs pops and rasps and farts gets mightily subdued to.............next to nothing. The boxes add as a fantastic heat soak too.

23-03-09, 08:26 AM	#3
Isimmo Super Moderator Classic Audi Club Member Join Date: Jul 2007 Location: Sissix-by-the-sea Posts: 15,218	As stated really, don't think it's too much off an issue as the 'flame' only really gets going beyond the tailpipe as more air becomes available. Our Ur belches flame so big sometimes you can see it in the rear view mirror, over the top of the bootlid spoiler. And I'm not making that up, there's several people on the quattroforum that have witnessed it. The exhaust has never been damaged, and neither has any rear trim. It's quite rare for a standard KV to get angry, but you're running something a little bit more 'special' so, even when running right, you might get a bit of bad behaviour like that. __________________ 1985 WR quattro, 1985 20vT RallyRep, 1993 MTM ABY S2 Avant. 2010 S3 Sportback.

23-03-09, 10:01 PM	#5
Booty Moderator Classic Audi Club Member Join Date: Sep 2007 Location: Deepest darkest Shropshire Posts: 5,077	Because you are running what is effectively mechanical fuel injection and the engine has no knock sensors controlled by an ECU, the cylinder keeps fueling and as it's not getting ingnited goes straight down the exhaust. Then becuase of the hot exhaust and highly flammable gasses, voila.....flames. You can of course 'help it along a bit' but me and Simmo will tell you how another day. You do need to get it fixed though as some of the fuel may wash the bores a tad if your rings are worn slightly __________________ 1987 Audi Coupe quattro - Clarion Tribute Car 2012 Audi A6 Allroad 2004 Mercedes SLK 350 2017 Mercedes GLA 220

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23-03-09, 07:23 AM	#2
Daveymaclad 4 ring whore! Classic Audi Club Member Join Date: Feb 2009 Location: Bursledon - Southampton Posts: 2,575	My very first CQ did that, bubbled a lot and I only realised it flamed when a friend of mine was following me! Mine was caused by a shitty replacement exhaust from the devil (euro car parts). In my experience, aside from some shocking fuel economy (due to the amount of unspent fuel you're forcing through the system) I don't think it's immediately worried! However I'm not sure how your local constabulary will think of it if they see it, or your MOT test station when that time comes!

24-03-09, 05:49 AM	#7
Alfashark Grown up member Join Date: Mar 2009 Location: South Waikato, New Zealand Posts: 41	Bad indeed mate, unburnt fuel is a great degreaser.... as such it can wash off the thin film of oil spread over the cylinder bores by the rings every time the piston moves up and down... metal on metal = scratched bores/damaged rings.

24-03-09, 08:54 AM	#8
86audicoupe Classic Audi Pervert! Classic Audi Club Member Join Date: Dec 2007 Location: Dorset Posts: 2,182	I get a lot of backfire and flames but this is through the side exit. Suppose it's a bit different though as the car is running fine but there's unburnt fuel/different back pressure when running with no silencers.