Quote:
Originally Posted by strada
Resurrecting an old thread. Got my F80 comp with MPE back in May, noticed some buzzing on startup. Only mod was Fabspeed midpipe installed by original owner.
Initially didn't think much of the buzzing on cold start it but eventually started looking at on forums. Initially suspected tips, then valves. Finally got around to making service appointment thinking it was going to be issue with valves but on video it seemed to be quite external as below.
When I took it in, the techs at BMW dealer sent me this, apologies for potato quality - had to screen grab from phone since I couldn't direct download.
Seems much like Sancho, Fabspeed mid is up against body/heatshield. Will likely need to bend away. But BMW also suggested this was causing slight misaligntment of MPE to cause buzzing against diffuser.
Not sure if I can bend the portion of heatshield away where it's closest by transmission or not. But I suspect it also explains the low rev rattle on throttle application in low gears.
I think next thing will be to loosen all bolts and see if I can reposition the exhaust to left a bit? Anyone else have any insight or experience? |
Looks like you have a couple issues. One is the midpipe making contact with the heat-shield. Adjust the pipe so that it isn't pressed up against anything. For more clearance bend the heat-shield away to ensure the mid-pipe is clear from hitting it. It can be done and won't take too much of an effort. I did mine by hand under a slightly raised car while on my back but feel free to use tools to make things easier (it's possible I may have also used the handle of my ratchet to help in a spot or two since I already had it next to me while under the car).
The other issue is related to your tips. There have been post regarding the CF tips on the MPE being an issue. It is clear in the video that the tips are definitely a culprit. The question is why. I am skeptical that you wouldn't have this issue with a stock midpipe.
It looks like the tips are loose, either with the bolt that secures them to the MPE, the rivets that fasten the CF to the metal pipe of the tips, or they are swinging because they are heavy. Could be due to the contact of the midpipe so start there first. Hopefully it's not swinging because of a cracked MPE. Consider removing the tips to see if you still have such a bad rattle.
Hope this helps!