Backfire?

[GillyC63]

Hi all
12 plate C63, no mods, happened a couple of times now, under hard acceleration & changing gear 3rd to 4th have heard what can only be described as a backfire! No fault codes, no EML, car pulls well & drives fine.
Any ideas as to what could be causing this noise?
Thanks for any replies.

 

[GillyC63]

No one?

 

[Bellow]

They all do that Sir?.......

 

[Petrol Pete]

Unburnt fuel going out the exhaust valves and igniting on the hot manifold = bang . Don't forget lot's of Yoof pay to have their car 'tuned' to do this and some manufactures have it built in as an option.

As Bellow says ^^^^

 

[Neiltodd]

They all do that Sir?.......

I thought the same

 

[Bellow]

I thought the same

And that it only does it on a full bore 3rd to 4th shift implies it's as it left the factory - no Rice Krispies remap.

Talking of, noticeably quieter round these parts since plod hammered down on the Kellogs clowns.

 

[GillyC63]

Thanks for the replies but my pre facelift PPP wagon never did this i'm pretty sure.