[brandonfrancom2]

Hi all.

I just installed a Catless DP (VRSF) on my M240i.

The car is performing as normal, or even better.

The issue is that on cold start, I hear a very loud metallic rattling/ticking sound, as if there's 50 metal BB's inside the DP. I confirmed the downpipe is not shaking, or rattling on any metal/shielding that's nearby. It only happens on the initial cold start, not when revving the car after it's finished the cold start cycle.

If I shut the car back off and turn it on again, the same thing happens until the "cold start" is over. Any ideas? It doesn't sound like a wastegate issue nor is it the exhaust flaps in the back, it is 100% coming from the DP area.

[BimBimM2]

Originally Posted by brandonfrancom2

Hi all.

I just installed a Catless DP (VRSF) on my M240i.

The car is performing as normal, or even better.

The issue is that on cold start, I hear a very loud metallic rattling/ticking sound, as if there's 50 metal BB's inside the DP. I confirmed the downpipe is not shaking, or rattling on any metal/shielding that's nearby. It only happens on the initial cold start, not when revving the car after it's finished the cold start cycle.

If I shut the car back off and turn it on again, the same thing happens until the "cold start" is over. Any ideas? It doesn't sound like a wastegate issue nor is it the exhaust flaps in the back, it is 100% coming from the DP area.

Maybe VRSF is particularly popular, but this forum has another thread with a CEL after VRSF. There is a reason why some downpipes are $1600 and some are $400. I don't know.

Posting here to keep an eye on this thread. Sorry about this issue!

[Sonertial]

I have something similar with a Wagnar 300 cpi Downpipe.

It's not hugely obnoxious, but was the first thing I noticed on installing the downpipe. As you say, it's only on cold start.

It made me worry that something was loose, and so I over tightened the clamp holding the DP to the turbo. Now the clamp has seized and I can't get it off, the nut spins in it's holder. I have bought a new clamp and will cut the old one off when I get an opportunity. I want to test the stock downpipe to see if the noise is still there, and then try catless.

My theory has been that it's the waste-gate rattling with the reduced back pressure. That or some kind of acoustic resonance effect in the DP. If you modulate the throttle the tiniest amount, it stops.

[JD11937]

Check that your mid pipe isn't hitting the cross brace, the tolerances are pretty close. But that would be coming more from rear of the car. Also exhaust flap has been known to rattle.

[alyabiev]

This "rattle" is just the typical exhaust sound when ignition timing is retarded due to cold start.

[brandonfrancom2]

Originally Posted by Sonertial

I have something similar with a Wagnar 300 cpi Downpipe.

It's not hugely obnoxious, but was the first thing I noticed on installing the downpipe. As you say, it's only on cold start.

It made me worry that something was loose, and so I over tightened the clamp holding the DP to the turbo. Now the clamp has seized and I can't get it off, the nut spins in it's holder. I have bought a new clamp and will cut the old one off when I get an opportunity. I want to test the stock downpipe to see if the noise is still there, and then try catless.

My theory has been that it's the waste-gate rattling with the reduced back pressure. That or some kind of acoustic resonance effect in the DP. If you modulate the throttle the tiniest amount, it stops.

Good point about the waste gate being an issue, as throttle completely stops the issue. Really hoping for a solution here. I do not think it's the pipes themselves rattling.


It's super odd. I'm debating bringing it into a highly rated BMW mechanic and having them diagnose, but I'd rather not spend $200 or more.


EDIT: So I found an exhaust leak from midpipe to DP. fixing and will see if rattle persists. I would assume it will stay.

[Mathew Miles]

Originally Posted by brandonfrancom2

Good point about the waste gate being an issue, as throttle completely stops the issue. Really hoping for a solution here. I do not think it's the pipes themselves rattling.


It's super odd. I'm debating bringing it into a highly rated BMW mechanic and having them diagnose, but I'd rather not spend $200 or more.


EDIT: So I found an exhaust leak from midpipe to DP. fixing and will see if rattle persists. I would assume it will stay.

Did the VRSF DP make contact with the metal under tray? I installed mine (catless version) and was not able to get it seated without it making contact with the tray. I will have to try adjusting it again sometime soon. Everything else seems fine. No leaks.

[brandonfrancom2]

Originally Posted by Mathew Miles

Did the VRSF DP make contact with the metal under tray? I installed mine (catless version) and was not able to get it seated without it making contact with the tray. I will have to try adjusting it again sometime soon. Everything else seems fine. No leaks.

Did you reuse the standard clamp to connect the mp to the dp? I have to go to a shop today to get it unwelded and a new clamp in place.

I’m not sure what you mean by metal tray. There was one thin metal support bar running right under it I moved for installation, which after reinstalling has a decent bit of clearance.

[Silvergram120i]

I have the same problem, look the video

[andres.psm]

Hello, there is a solución for this sound?
I have the same sound from I installed vrsf catless downpipe to my m235i.
Today I change the DP to MP clamp for a new one thinking that would be the solution. But the sound persist.
I think that could be the turbo to DP gasket. I hope no.

Here is a video with the sound. Only exist in idlle.

[HarryCoyote]

I have a 2017 M240i with a Dinan tune and a Dinan midpipe and a Dinan Muffler. All was good for about a two years then I am having the same issue with the sound at start up. It sounds like the exhaust is hitting the bottom cross over or tattling against something. I am not sure what the problem is either. I have had it back to BMW and they state the pipes are all tight. Let me know if you figure it out and I will do likewise.

[helloelectro]

99.9% your midpipe was twisted on install and is hitting the cross brace.

[Kobylash]

I have the VRSF downpipe on my M240i xDrive and it does come into contact with the metal plate near where the exhaust connects to it. I've tried to fix it and it improved but I still get it if the car is stopped on an upward slope or if I put my foot to the floor while cruising.

One thing to note is I believe that metal plate is only on the xDrive model, not the RWD.

I've pretty much given up on fixing it and am considering ordering a downpipe with the bracket and better fitment (ER is my current choice).

[4Hockey4]

My Active Autowerkes Catted was a seamless and quiet install. It was $1K though

[Kobylash]

Originally Posted by Kobylash

I have the VRSF downpipe on my M240i xDrive and it does come into contact with the metal plate near where the exhaust connects to it. I've tried to fix it and it improved but I still get it if the car is stopped on an upward slope or if I put my foot to the floor while cruising.

One thing to note is I believe that metal plate is only on the xDrive model, not the RWD.

I've pretty much given up on fixing it and am considering ordering a downpipe with the bracket and better fitment (ER is my current choice).

Thought I'd post an update on this issue, turns out the ER downpipe makes even more contact with the plate. However, the ER pipe comes with a set of washers to shim the plate (not that they mention what these are for anywhere in their install instructions). With these installed I have no issues.

On the note of ER vs VRSF the ER pipe definitely seems to be much higher quality. Better welds, nicer flex pipe section, better bends. And I do feel better having that bracket even if it wasn't the source of my plate contact rattle.

So for anyone with an xDrive model assume you will have to shim this plate for proper clearance.

[xthiagodias87]

Hi andres.psm, you solved The problem?
I have this too

Originally Posted by andres.psm

Hello, there is a solución for this sound?
I have the same sound from I installed vrsf catless downpipe to my m235i.
Today I change the DP to MP clamp for a new one thinking that would be the solution. But the sound persist.
I think that could be the turbo to DP gasket. I hope no.

Here is a video with the sound. Only exist in idlle.

[seanroberts000]

Originally Posted by Kobylash

I have the VRSF downpipe on my M240i xDrive and it does come into contact with the metal plate near where the exhaust connects to it. I've tried to fix it and it improved but I still get it if the car is stopped on an upward slope or if I put my foot to the floor while cruising.

One thing to note is I believe that metal plate is only on the xDrive model, not the RWD.

I've pretty much given up on fixing it and am considering ordering a downpipe with the bracket and better fitment (ER is my current choice).

FWIW, I ordered the CTS high-flow downpipe -- zero issues with fitment or rattle, and it was in the VRSF price range.

[Info@mad-us.com]

Don't have any rattles with our downpipe. You sure its not touching anywhere or its not the valves themselves?

[NewWorldOrder]

Originally Posted by brandonfrancom2

Hi all.

I just installed a Catless DP (VRSF) on my M240i.

The car is performing as normal, or even better.

The issue is that on cold start, I hear a very loud metallic rattling/ticking sound, as if there's 50 metal BB's inside the DP. I confirmed the downpipe is not shaking, or rattling on any metal/shielding that's nearby. It only happens on the initial cold start, not when revving the car after it's finished the cold start cycle.

If I shut the car back off and turn it on again, the same thing happens until the "cold start" is over. Any ideas? It doesn't sound like a wastegate issue nor is it the exhaust flaps in the back, it is 100% coming from the DP area.

The exhaust is touching something underneath. Had the same issue when I installed the Remus. Just had to move the exhaust over a bit, and I haven't heard the sound since.

[jLona240]

Originally Posted by brandonfrancom2

Hi all.

I just installed a Catless DP (VRSF) on my M240i.

The car is performing as normal, or even better.

The issue is that on cold start, I hear a very loud metallic rattling/ticking sound, as if there's 50 metal BB's inside the DP. I confirmed the downpipe is not shaking, or rattling on any metal/shielding that's nearby. It only happens on the initial cold start, not when revving the car after it's finished the cold start cycle.

If I shut the car back off and turn it on again, the same thing happens until the "cold start" is over. Any ideas? It doesn't sound like a wastegate issue nor is it the exhaust flaps in the back, it is 100% coming from the DP area.

Just wondering if you found a solution?

I installed my AA downpipe and I have a rattle sound on cold start that stops after the cold start cycle.

I'm guessing my midpipe is hitting the rear support brace?

[BMW335l]

I also have a rattle on cold start that I can hear when Im driving as well. Any idea what this can be?
I had rattle before DP install, and I guess the catless DP just makes the rattle louder. I first thought it was the exhaust valve, but I changed it without success. It sounds like the rattle is coming from the middle of the car.
https://youtube.com/shorts/Rj9Ch3rIdkA?feature=share