[StannisBaratheon]

Originally Posted by Rockyca

Does anyone know the cause of this yet?

Cylinder 6 is getting too hot. Metal expands when it heats up, if something is blocking the expansion, like a cylinder wall or piston ring, then the expansion will go through the path of least resistance.

[Rockyca]

So how do we prevent it from happening?

[StannisBaratheon]

Originally Posted by Rockyca

So how do we prevent it from happening?

I'm not an engine builder or expert, but we'd have to narrow down exactly what is happening because it could be a single factor or the combination of multiple factors. Rings gapped too tight, cast pistons not strong enough, fuel/air mix too lean, detonation, thin oil, all of those things can contribute to a failure.

It could be as simple as casting defects in the pistons - If you watch the Papadakis Racing B58 build series on youtube you'll see they re-used the factory rings and gap for their 1,000 HP build so I don't think the rings are the problem. I see thin oil mentioned sometimes but doesn't thicker oil generate more friction (which generates more heat)? Not sure about this one but I don't think it's a significant contributing factor.

Pistons are made by Mahle and are cast - There is endless debate on casting vs. forged but generally speaking forged pistons are reliably stronger than cast. Cast pistons/cranks/rods/gun parts can be great or they can be junk depending on the quality of the casting process. I'm also not sure what alloy the metal is but maybe it's too hard/brittle? Doubtful but who knows. A leaner air/fuel mixture will certainly generate more heat and could lead to detonation. I don't think detonation is the cause but if there is a casting defect in a piston then enough heat and detonation could cause it to fail.

My guess is that the extra heat in cylinder 6 is too much for the piston and for what ever reason (casting defect, alloy, etc.) it fails. The fix would be to replace the stock pistons with stronger forged pieces, but I think that's overkill for what seems to be a rare occurrence.

[bk335ilci]

Watch this video at the 6:50 mark. He explains the difference in the comp temp sensor. How the b58 it's in the front of the engine and on the 58tu it's in the rear of the engine near cylinder 6. I wonder if this the problem?

[Rockyca]

I remember mg flasher having a sport cooling option with their tune... perhaps keeping this in the cooler setting might help?

[kianf22]

Originally Posted by Rockyca

I remember mg flasher having a sport cooling option with their tune... perhaps keeping this in the cooler setting might help?

Would like to know as well

[kern417]

It's primarily a function of the throttle body position. It makes it more difficult for all cylinders to get an equal amount of air. But it's more common when using fuel/meth injection in the throttle body. If you're not doing that, then you don't have much to worry about.

[f82_spooly]

So is this limited to the 2016 B58? Has anything changed in 17-18?

[Ivan_Uzi]

Hi guys, I bought F33 440i, late 2017 registration, initially I installed MPPSK + exhaust from BMW, then installed MST intake with a downpipe and bought Bootmod3+XHP and run the aggressive burble stage2 and xhp stage 3 for like 3 months when I started getting "Drive Train" error after I reach 200 km/h. I cleared the code and continued driving when a month ago I got the same error but it didn't clear, the car was shaking and producing thick white smoke, I was 20 miles away from home so drove with the symptoms to my house, tolled it to my mechanic and I we are opening the motor, tomorrow will visit my mechanic to see the damage and purchase the parts. Initially on the log the misfires appeared on cylinders 2 and 6, replaced the injectors and only cylinder 2 remained with an error, did a pressure test and it had 3 bars pressure. Because of an open injector, it has flooded the all of the cylinders and spark plugs were wet. I assume I am one of the "lucky" ones and will have to fix at least one bored cylinder and replace the piston, I just hope there are no other cylinders damaged. I will replace all other 4 injectors as well because I am afraid now that it may happen again if I only replace 2 of them (cylinder 2 and 6). I ordered the TU pump to upgrade as well and I just hope it does not happen again because it is 4 to 5 digit cost for the fix. Tomorrow will know for sure what was the damage because of the failed injectors.
I have around 35k miles on it and only replaced oil and filter for the past 1 year of ownership.

[SimonBMW1]

I have a stage 1 MHD 440i. Burbles are aggressive. is this likely to cause issues. Been running for 2 years now. 2017 reg