Can this really be put down to cheap supermarket fuel

Hi,

Friend of mine has a 4 year old BMW mini which recently had the problem pictured below and a £600 bill. The garage have said it was due to using cheap supermarket fuel.

I really don't understand that, surely most likely caused by pre ignition or a very weak mixture. Firstly with all these computers on board modern cars don't they adjust the mixture etc, I thought that the chances of the mixture being weak were negligible, there again the engine is post 1935 so what do I know.

Secondly there has long been a debate that actually super market petrol comes from the same tanks as non supermarket a ron is a ron. Tescos do their own equivalent to shell optimax which many with high performance engines use

I have suggested it might be worth pointing this out to BMW in his usual diplomatic way, he is a blunt Yorkshire man ( I like what I know and I know what I bloody well like ) and see what they have to say about it.
 

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Pete McCluskey.

Lifetime Supporter
Nick I'm a bit like you, if it's not pre 1935 I'm a bit lost. But I also doubt it is down to cheap fuel. I'm guessing something seriously wrong with the computer fuel mapping. Maybe a sensor on the blink.
 

Randy V

Moderator-Admin
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Admin
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Looks like a bad valve guide/seal problem contributed to a detonation problem for that cylinder.. I wouldn't give you $.10 for the top ring and ring land in that cylinder...

Sometimes the ECU can't pull out enough timing or pull it out fast enough to control oil fed detonation like that..
 
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