Quote:
Originally Posted by Downunder99
Update 20-Nov-2018:
Allright, brought my M2 to the dealership, they were able to replicate the rattle, but did not do much root cause analysis, they just ordered a brandnew MPE including tips, installed it and then figured out that it is in fact the tips. The foreman put it on the hoist for me and I can now clearly see what the issue is: the inner, perforated pipe of the tips, onto which the carbon fiber tips are rivetted, must be pushed all the way in to have a conical seat with the exhaust pipe. Those who installed or uninstalled the tips themselves know, that the tips are only held in place by the conical seat on the pipe plus one tiny little screw which is holding the tips in place in the horizontal plane. You can move the tips backwards and fix them in place, but you lose the conical seat. Under normal circumstances, this rather underwhelming piece of engineering, with the conical seat plus the tiny screw, should not rattle, but!! as soon as a) temperature changes, i.e. colder weather, or b) the tips are adjusted backwards to align for example with the diffuser and don't sit on the conical seat anymore, or c) the tips move slightly away from the conical seat through vibration over time, the front end of the tips, which is usually tight with the exhaust pipe where it increases in diameter towards the welding, has some gap! Now combine that with the cold start frequency and the movement of the exhaust pipes during cold start, the inner pipe of the tips is rattling against the exhaust pipe like a baby rattle! So, that is the reason, why I got my M2 back, with the left side tips sticking out 2/3" further than the right side tips! The foreman showed me that all tips are pushed all the way in, so they sit snug on the conical seat. And as the exhaust has its pipes cut/welded slightly different in length (how the heck did it go through the quality control of the exhaust manufacturer, with 2/3" difference in length!?), I have now the option of tips, which are aligned on both sides with the diffuser, or I adjust the right tips 2/3" towards the back and lose the conical seat, increasing the rattle during cold start.
In summary: horrible tolerances in production of the MPE base exhaust and an anything but sufficient way of holding the tips in place.
P.S. I should mention that mine is the MPE which came with my 2018 M2. I read further up on the page that earlier versions may have an issue with the exhaust clamp itself. That for sure seems to be a different issue.
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And that ladies and gentlemen is why I didn't buy an MPE