**Resolved** Help - strange noise in third and forth gear (with videos)

[BlatantMaple854]

Hello everyone,

I have a 2017 ZCP DCT f80 M3 with a strange vibrating/grinding noise when accelerating between 2500 and 3500 rpm. Happens mostly when the vehicle is cold but have encountered the issue when warm as well. Seems to appear more often when going up hill.

The car is going into service tomorrow for a ride along, but we all know sounds seem to disappear as soon as a shop Forman is in the passenger seat. Please see linked videos below.

Does anyone have any idea of what could be causing this issue? Thank you so much for any replies!!

[silvergray545]

Really hard to tell from the video. Could be something silly like a heat shield or it could be something like a wastegate rattle. Keep us posted.

[Aaaaaaaaa]

The F30 N55 cars had a similar issue. Don't know how helpful it would be but here's the thread:
http://f30.bimmerpost.com/forums/sho...d.php?t=949816

[BlatantMaple854]

Could this be engine knock?

[lukej]

Kind of a dumb question but are you running premium .. ??

[BlatantMaple854]

Yes, absolutely every time. I fill up at a fairly new shell gas station with premium 93. Only one time, I accidentally mixed 4 gallons of 87 with 12 gallons of 93. Which averages out to about 91.5 octane (still better than Cali gas lol)

Originally Posted by lukej

Kind of a dumb question but are you running premium .. ??

[2jssepa]

I think I hear something similar but only when cold. Are you stock?

[BlatantMaple854]

Originally Posted by 2jssepa

I think I hear something similar but only when cold. Are you stock?

Completely stock and it turns out the noise is present even when fully warmed up and under load.

[FirstF80InSpace]

Definitely not normal. I tried listening for a similar sound in my car and nothing. Let us know how your dealership visit goes. Curious as to what the issue may be.

[Ever.]

Weird. I had this similar noise on my old E92 M3. Seemed to be coming from somewhere in the dash. Dealer never figured it out. It never really affected performance or anything either so nothing was done in the end, and it was faint enough where you wouldn't be able to hear it if you weren't paying close attention.

[BlatantMaple854]

Originally Posted by Ever.

Weird. I had this similar noise on my old E92 M3. Seemed to be coming from somewhere in the dash. Dealer never figured it out. It never really affected performance or anything either so nothing was done in the end, and it was faint enough where you wouldn't be able to hear it if you weren't paying close attention.

Hopefully, that’s not what’s going on here. I hate unknown noises. Car is still with the dealer. I hope to here an update today.

[sandjam]

Definitely not normal, but also definitely not the DCT. Let us know what they find.

[2jssepa]

Hi OP,

Any feedback after your visit to the dealer?

[BlatantMaple854]

Originally Posted by 2jssepa

Hi OP,

Any feedback after your visit to the dealer?

Nothing definitive yet. The tech thinks it could be the carbon front splitter and lip are lose from a poor installation. They are ruling that out first before they try anything more teachnical.

I have my doubts about that being the issue...

[BlatantMaple854]

Quick Update: tightening loose bolts in the bumper did nothing. They also changed the blower motor and replaced the valvetronic motor. No change...

An engineer will be at the dealership on Friday to take a look. I am starting to get really pissed off. I’ve been without my car for over a week and a half.....

[BlatantMaple854]

Quick update for everyone. My dealer / service techs were finally able to resolve this issue after at least 4 visits with no luck. The noise was found to be only present when the ac was running. My service tech added an additional weight and clamp on the low pressure line for the ac system. The issue is 100% resolved! Hope this helps anyone in the future with the same problem.

[Aaaaaaaaa]

Originally Posted by pheerlx

The F30 N55 cars had a similar issue. Don't know how helpful it would be but here's the thread:
http://f30.bimmerpost.com/forums/sho...d.php?t=949816

Turns out The link I provided had the solution all along! Did you see it earlier?

[BlatantMaple854]

Originally Posted by pheerlx

Turns out The link I provided had the solution all along! Did you see it earlier?

I sure did, and I informed my SA about this back several months ago. The tech stated, “there was already a weight on there and that was not the problem.” Sure enough, the weight was not enough. They added an additional weight on the low pressure line near the firewall and that did the trick. Pretty disappointed in what I had to go through to resolve this issue...

[Aaaaaaaaa]

Originally Posted by BlatantMaple854

I sure did, and I informed my SA about this back several months ago. The tech stated, “there was already a weight on there and that was not the problem.” Sure enough, the weight was not enough. They added an additional weight on the low pressure line near the firewall and that did the trick. Pretty disappointed in what I had to go through to resolve this issue...

Now that you mention it I still heard that rattle in my 435 and it already had the weight on there too. I think I hear something similar on very initial application of throttle at cruising speeds in my current M3 but it's not as loud as the one in your videos.