MPE on E92

[calbear13]

I just got an M perf exhaust installed on my car today. This was purchased used with about 8k miles on it. I noticed two things -

1. In a certain rev band, around 3-4.5k rpm, there is a very deep "resonance" type sound. Is this what's known as drone? I thought the MPE doesn't have any drone. Is this normal?

2. I drove for a couple of hours today and overall it was great. However, after I started up my car again a few hours after installation, I stopped at a traffic light and noticed the engine revving slightly intermittently by itself. My foot was on the brakes and the engine was going back and forth between maybe 1k and 1.2k or 1.5k rpm. Is this something to be concerned about?

[Foolclear]

i have the MPE with 17k miles on it. to answer your first question that sound is normal since it broken in its to be expected, but its very small amount of drone you have to listen really hard to hear it. 2nd question probably the computer getting used to the MPE exhuast. drones like porn you know it when you see it or in this case hear it lol

[calbear13]

Thanks

[RadM5]

Am I alone in kind of liking a little drone? Sort of like hearing the heartbeat! I have mpe as well...

[calbear13]

You hear it too? Same rev band? I kind of like it too but just want to make sure it's normal and not due to something wrong with the exhaust or installation.

[auggiem3]

I don't have drone in any rev range with my mpe. The 3-4k zone is the sweet spot for sound.

Your drone occurs higher in the range than most aftermarket exhausts (1.5-2.5k) and the idle issue is abnormal.

I've heard these symptoms before - they were associated an improper installation of the mpe - let me try to find the thread. A European member had a loose bolt if I remember correctly. He rode in other cars with mpe to prove the issue to the installer.

[calbear13]

Thanks, I will get it checked out this week. Found the thread: http://www.m3post.com/forums/showthread.php?t=579106. Thanks!

[Gsv77]

OP, I noticed a drone sound between that rpm band but also had this at startup

If yours doesn't ever sound like this video at start up then it is likely fine. Mine in the video was replaced under warranty.

[calbear13]

@Gsv77 no it doesn't sound like that. I'll get the installation checked out this week in case something is loose. Is it safe to drive meanwhile or if something is loose, would I be causing more damage by driving until it's fixed?

[auggiem3]

Originally Posted by calbear13

Thanks, I will get it checked out this week. Found the thread: http://www.m3post.com/forums/showthread.php?t=579106. Thanks!

Thats the thread...good luck.

[calbear13]

Thanks