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Gurgling and popping exhaust on overrun

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Can anyone explain what the gurgling and occasional popping noise made from the exhaust on the overrun is? I had a VR6 golf and it made a similar type of noise and you hear Scoobies make it a lot.

 

Cheers

 

Chris

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Overfueling meaning that unburnt fuel hits the hot exhaust, which is why it should only happen when the car is warm.

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I have to say that I don't think it only happens when its hot. Also my golf made similar sounds. I hear lots of sports cars making the same type of sound and I don't think it has anything to do with a leaky downpipe. Does anyone have any other ideas?

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The reason I mention the leaking downpipe is that the leak is before the lambda sensor and therefore the lambda probe is relaying an incorrect fuel mixture leading to an overrich mixture, hence the unburnt fuel. I am going by what my stealer told me on this one.

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My car does this, think it always has, i dont worry about it.

 

A lot of Nova/ Corsa drivers would pay for an exhaust that burbles and pops all the time.

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Overfueling meaning that unburnt fuel hits the hot exhaust, which is why it should only happen when the car is warm.

 

ive got a pulsar gtir atm and it pops and bangs all the time, including from dead cold

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Overfueling meaning that unburnt fuel hits the hot exhaust, which is why it should only happen when the car is warm.

 

ive got a pulsar gtir atm and it pops and bangs all the time, including from dead cold

 

That's why I said should ;)

 

Something must be hot enough to be igniting the fuel though :?:

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true.

 

but i can get up on a cold morning and drive down the road i will literally get big pops an bangs within 50 yds or so

 

 

 

ive seen the light anyways ;) and the pulsar is hopefully going on saturday and then its time to seriously start looking for a vr6 corrado

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Thanks for all the replies everyone. Last night I was walking home when a new Porsche turbo passed me slowing down with lots of rude gurgling noises coming from the exhaust. If a new turbo does it then I'm not worried about my Corrado doing it!!!!

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I had an interesting chat with Vince about this and the VR head in general today. I learned that the back 3 cylinders are the hottest running ones and the exhaust valves in these 3 almost glow red when going for it. This is why the valves and seats start pitting at around 30K and by 100K, they're pretty well past it but because at full throttle the valve train is moving so fast and so much air is being sucked in, you don't really notice it. It's on part throttle and midrange acceleration you notice it the most. I did notice a massive improvement in general smoothness and low and midspeed pull after my head was done, I have to say.

 

So anyway, if your VR is popping really badly on overrun, you might have badly pitted valve seats. But other things such as leaky exhausts, leaky injectors, dead O2 sensor and free flow exhausts can also cause it.

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Mine pops on the overrun a little - but its more of a burble.... and only when hot.... interesting info there Kev - will be checking out the exhaust valves when the engine comes apart...

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