[Koray K]

Just recently installed 3" ARM catless downpipes on my 2007 e92 335i, and on the first startup after installing the downpipes I am getting a loud whining noise from the turbos when they build boost. The car sounds as if it has a supercharger. This has me very worried as it sounds just like every video with a blown turbo that I've seen. I've went back under the car and checked v band clamps, O2 sensors, inlets, outlets, intercooler connections, and the charge pipe, and found nothing wrong. When driving it, as soon as you try to go WOT a engine malfunction comes on the screen, and the car has damn near no power. I scanned the codes and only got P0036 and P2402, both of which have nothing to do with the turbos or boost. On cold start the whining is very loud, even at idle, but slowly quiets down as the idle drops. It gets to a point where you cant hear it at idle but you can hear it clearly when revving past about 3k. Disconnecting the vacuum canisters makes the sound much much quieter, but it is still there when you rev it. The car has 82k miles and never did this before. It sounds EXACTLY like this video:

. (not my video) Any help would be greatly appreciated as I wanna get it back on the road ASAP. Thanks.

[TSilver335i]

Originally Posted by Koray K

Just recently installed 3" ARM catless downpipes on my 2007 e92 335i, and on the first startup after installing the downpipes I am getting a loud whining noise from the turbos when they build boost. The car sounds as if it has a supercharger. This has me very worried as it sounds just like every video with a blown turbo that I've seen. I've went back under the car and checked v band clamps, O2 sensors, inlets, outlets, intercooler connections, and the charge pipe, and found nothing wrong. When driving it, as soon as you try to go WOT a engine malfunction comes on the screen, and the car has damn near no power. I scanned the codes and only got P0036 and P2402, both of which have nothing to do with the turbos or boost. On cold start the whining is very loud, even at idle, but slowly quiets down as the idle drops. It gets to a point where you cant hear it at idle but you can hear it clearly when revving past about 3k. Disconnecting the vacuum canisters makes the sound much much quieter, but it is still there when you rev it. The car has 82k miles and never did this before. It sounds EXACTLY like this video: www.youtube.com/watch?v=_TvT0PMhizw. (not my video) Any help would be greatly appreciated as I wanna get it back on the road ASAP. Thanks.

I know it's not your video, but it's quite amusing how they left the BPV/BOV unplugged blame the turbos. Quote from the videos description "This is the sound when a turbocharger ingests some FOD (foreign object damage) and needs to be replaced. The "Woo!" Is the impeller imbalanced and damaged".
So to actually fix the problem they replaced the turbos. I'd hate to be one of their customers lol.

Just like everything it's in plain sight and no one has the eyes to see. I hope your not that silly

But seriously if it sounds like that it's gotta be a major boost leak check intercooler piping and charge pipe connections etc

[335xiE90]

That sounds like a boost leak to me too. This type of stuff scares me away from doing downpipes.

[335xiE90]

Sorry one other thing....The inlet being loose and not pressed in all the way in the turbo might cause that too.

[R3dLeader]

Originally Posted by 335xiE90

That sounds like a boost leak to me too. This type of stuff scares me away from doing downpipes.

Not touching anything on the pressure side when installing downpipes. There is is zero risk of causing a boost leak on the intake side.

The biggest risk is installing the v-band clamps in the wrong orientation and blocking the wastegate actuator from closing.

OP, you need to double check your v-band clamp orientation.

I have installed catless downpipes twice on two different cars and BOTH of them have turbo whine afterwards, no underboost codes, and pull hard to redline. I consider the whining noise normal. You get more "turbo noises" with catless downpipes.

[Koray K]

Originally Posted by R3dLeader

Not touching anything on the pressure side when installing downpipes. There is is zero risk of causing a boost leak on the intake side.

The biggest risk is installing the v-band clamps in the wrong orientation and blocking the wastegate actuator from closing.

OP, you need to double check your v-band clamp orientation.

I have installed catless downpipes twice on two different cars and BOTH of them have turbo whine afterwards, no underboost codes, and pull hard to redline. I consider the whining noise normal. You get more "turbo noises" with catless downpipes.

I checked the v band clamps and made sure they are not in the way of the wastegate actuators, and they’re all good. I know a louder turbo noise is definitely normal for catless downpipes but I think this is beyond that. I got a vid of it drivinf earlier, it really sounds like blown turbos. Also it started smoking out of the exhaust earlier. https://youtube.com/shorts/JonfP0IMpQs?feature=share

[Koray K]

Today, upon pulling into my driveway after coming back from a mechanic that works on and builds many n54 engines who told me my turbos are toast, the sound just suddenly stopped. Now im thinking its one of two things, the bad turbo seized up and is just no longer spinning, or, maybe there was something stuck in the turbo and it finally made its way out. The car is still extremely slow and is in a constant limp mode, with the engine malfunction popping up every time i step on the gas. Any ideas? How can i check to see if I am making boost or not?

[Koray K]

Finally threw a 30ff code today, almost 100% positive that the bad turbo ended up locking up which caused the noise to go away.