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BMW B48 Piston Failure Analysis

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Good day all,

See attached, my friend has a less aggressive tune than me.

Previously he was on a chiptune and switched to remap.

Not too long after tuned he noticed a rough idle (less than two weeks).

Basically, he is a good friend of mines so I know he maintains his car properly.

Unsure how his piston ringland failed as I used the same tune (remap) with no issues and now, I am on a more aggressive tune.

I am doing the rebuild, should be starting up car this week.

Forged CP Pistons and CP Rods installed.

Will keep him on stock map for break-in period then will get some logs after stock and then with stage 2.

I am also seeing on forums that plenty b48s having this issue.

My car is pushing more than most of them so unsure how my pistons still good.

Both my friend's car and mine are identical.

My uncle who runs the machine shop was suspecting too much heat caused by too much boost.

Initially when he was getting the rough idle, we switched injectors and his misfire faults moved with the injector so I am suspecting one of his injector faulty which caused that cylinder to run a bit lean causing the ringland failure.

Appreciate if you can review and advise what you think caused piston ringland failure.

I will document the rebuild process and share with others.

Thank you.

Regards,

Shane

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Hello very hard to tell without seeing the plugs and piston tops and combustion chambers and bearings but a quick guess is at some point it has had some knock that has done some damage and it has got worse over time

the best bet is to check the injectors and everything else you possibly can before leaning on the engine

Regards Ross