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Unwanted flames!!!

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When changing gear at high revs, I can quite often hear a poping noise coming from the exhaust. It wasnt till my friend was following me tht he told me he could see flames coming from my exhaust. Not massive ones but very noticable.

 

I've got a cat back, SS sytem, and my cat was removed. I got my mixture level checked and its ok.

 

The previous owner drilled the airbox and i covered up the whole, but tried it uncovered recently (which sounded horrible) and the exhaust stopped popping!!!

 

(2.0L 16v)

 

Why would this be happening.

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Flames are generally caused by over-fuelling, and more often than not when the timing has been advanced, causing the car to run richer.

 

The airbox modification changing the amount of O2 being drawn into the engine, plus some lazy retardation by the engine, will cause the odd flame-burp.

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Fuel economy would probably be down, but the car would probably be pretty quick.

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A weak mixture burns slowly and can still be burning after the exhaust valves open.

Checking the mixture at tickover doesn't really tell the whole story. It is very possible that the mixture is incorrect at high revs, only a trip to the rollers would tell you for sure.

Also not having a cat will make it much more likely to happen. My/Darrens Golf with only 2 silencers used to flame a treat. More than a few people commented about it on trackdays.

gavin

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I like flames! :D

Though i have fixed that issue on my G60 with a brand new exaust.

The other one was full of rust and holes! :lol:

No more popping while changing revs anymore...

I´ve kind of miss it...

LOL

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mine bangs/pops out the exhaust when changing up 8)

 

mk1 used to toast the unlucky motorist behind before i had it set up :lol:

 

neil.

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I blew through 3 exhaust systems because of my ability to shoot flames. 2 dynomax's and 1 magnaflow, still on the magnaflow cause its straight through.

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Both my Golfs; Mk1 1600 GTI & Mk2 8V GTI used to do this. My C did it when it had a de-cat pipe, but not now its got a cat. My C's mixture is set as per Bosch instructions, by measuring the current from one of the connections on the metering head, the timing is set to 6 deg BTDC, it passed it's mot and looking at its power it must be pretty well set up.

 

I used to love ripping passed slow people in 2nd and changing up into 3rd with the exhaust level with their drivers door in my Mk1 Golf.

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I find that my ezhaust spews flames in every gear when I rag it and make the gear change 'sudden', rather than easing in the clutch. I've stopped doing it now because I probably look like bit of a fool, and it melts the rubber exhaust mounts :/

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In Canada we don't actually have the 16V Corrado but here's what happens on the VR6 & why. Most cars use what is called a reactive fuel injection system, this means that a change has already happened before the ECU can react to it. The VR6's use three resonators, the first and last as simply small mufflers and the middle is used to reducing the popping sounds when you are slowing down with the throttle closed and to reduce back fires & arrest flames. To make a VR6 barf flames you remove the centre muffler and then remove the dashpot from the throttle body. Now, when you are driving you snap the throttle shut and some raw fuel will enter the cat and then ignite thus shooting flames out of the tail pipe. The dash pot is used to allow the throttle to slowly close and ths allowing more air to enter the cylinders. I would look at a rich running condition, chips, dash pot, O2 sensor, or the blue ECU temp sensor and make sure they are all operating as they should.

 

Cheers, Dennis

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