Popping and banging on the overrun

[Paul Coleman]

My S1 pops and bangs when I take my foot off the gas. I drove it yesterday and as I was driving through the narrow streets of a village the pops and bangs were being amplified by the surrounding buildings. At one point I felt like I was in a clown's car at the circus!! What causes the popping and banging and how can I reduce it?

I have a full stainless steel exhaust from SJ.

[ChrisJ]

Both mine do that - the Esprit much more so than the Excel.

Which village? I want to have a go

 

[peteyg]

Mine pops on the overrun too. I have the same exhaust as you. I like the popping but sounds like you have something more serious. Check fuel mixture, ignition timing or leaks in the exhaust system.

[Paul Coleman]

It seems worse when the weather is warm, as it was yesterday. The car was set up at SJ Sportscars and I haven't touched it since.

But what actually causes it - is it raw fuel being ignited in the hot exhaust?

[gvy]

My original cast manifold had a crack in it, and the popping and banging on the overrun was bad (like you mention, a clowns car) Using exhaust pasta on the bad flange helped for 3 rides and then it was the same.

Now with the new Stainless steel exhaust system from SJ, the banging stopped but it does still pop when lifting the food in 2th. But this popping sounds OK,  The banging is gone.

And yes, when it is hot it pops more.

Geert 

[Andyww]

43 minutes ago, gvy said:

My original cast manifold had a crack in it, and the popping and banging on the overrun was bad (like you mention, a clowns car) Using exhaust pasta on the bad flange helped for 3 rides and then it was the same.

 

Never tried using pasta on the exhaust, how about olive oil in the engine?

Mine usually makes a loud pop around 10 seconds after stopping the engine, which is strange.

[Paul Coleman]

After a run of about an hour today I pulled onto a roundabout and the thing just died (as though it was fuel starvation) and then gave an almighty back fire, at which point it then picked up again. Very strange...