The engine makes a loud noise and is rumbling loudly?

Tiny
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  • 2017 BMW 430I
  • 2.0L
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 34,000 MILES
I'd really appreciate any help with this. I just installed a MAD BMW cold air intake on my vehicle listed above and I am now experiencing problems. Just after installing the intake, the engine was fine (with idling/small revs), but after starting it up again after a few hours of not driving, the engine is making a lot more noise and rumbling very loudly.

The engine bay noise (standing outside the car) is noticeably louder, and inside the cabin, there's a very loud rumbling/shaking noise. I checked all of the clamps, and everything seems to be sealed correctly. Would it possibly be a MAF sensor error? I'm not sure if this would relate, but I accidentally dropped a wrench into the engine bay, that I haven't been able to get out.

First time modding my car, and hope this isn't a major issue. Thanks for any advice.

The audio is linked to soundcloud, and is the car starting -> idling.

https://soundcloud.com/throwaway1101/img_3693
Monday, April 28th, 2025 AT 6:10 AM

10 Replies

Tiny
KEN L
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Yep, it sounds like the wrench is making the noise, can you please shoot a quick video with your phone so I can hear the noise? That way I can tell for sure what's going on. You can upload it here with your response. Also, do you have any warning lights on?
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Monday, April 28th, 2025 AT 12:03 PM
Tiny
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Thanks for the help. I'll add a video once I get home, but here's a link to the audio recording I took last night of the problem: https://soundcloud.com/throwaway1101/img_3693 (Audio is taken from inside the cabin). I don't have any warning lights on. I'd assume that a MAF issue would trigger a CEL? Also, not sure where the wrench would've landed to make this much noise- I wasn't able to see it or retrieve it last night.
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Monday, April 28th, 2025 AT 1:46 PM
Tiny
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Here's a quick video. After around 30 seconds of idling the noise starts.
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Monday, April 28th, 2025 AT 5:37 PM
Tiny
KEN L
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It sounds okay to me, is the noise coming from under the hood? If so, that is where the video needs to be taken when the engine is making the noise. Also, I would turn the HVAC system off so you can see if that might have something to do with it.
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Tuesday, April 29th, 2025 AT 9:49 AM
Tiny
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I can't really hear the noise from the outside, only while sitting in the car. It sounds fine to me as well for the first 30 seconds, but then the noise/rumbling starts. I'll try your suggestion with turning the HVAC off, otherwise I'll probably reinstall the stock intake to see if that was the problem.
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Wednesday, April 30th, 2025 AT 12:59 PM
Tiny
KEN L
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I can tell more if you can get a video from under the hood?
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Thursday, May 1st, 2025 AT 9:43 AM
Tiny
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Here are two videos-this is with the stock intake back on. I tried turning the HVAC system off, and it sounded the same.
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Thursday, May 1st, 2025 AT 6:23 PM
Tiny
KEN L
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Thanks for the videos, that noise is a good one, have not heard that one before. If I had to choose something to try I would swap out the fuel rail pressure sensor because the fuel pressure sounds like it is running to high. We need to run the scanner on the car, here is a guide to help, even though there is no check engine light on you can still have codes FYI.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please go over this guide and get back to us.
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Friday, May 2nd, 2025 AT 9:47 AM
Tiny
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Quick update, got the car on jacks and took off the pan, and was able to get the wrench. The noise went away, so seems like that was it after all.
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Wednesday, May 7th, 2025 AT 1:29 PM
Tiny
KEN L
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Nice work! Let us know how it goes or if you need anymore help.
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Thursday, May 8th, 2025 AT 10:44 AM

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