[lwgrenier]

Does anyone know if leaks between the turbo and downpipe are common on our cars? Ive been getting a lot of strange whirring noises on top of the additional turbo noise at all rpms lately. It seems like the n55 turbo is pretty robust so I’m hoping it’s not the actual turbo going. I’m also not hitting boost targets which could partly be a result of a leak in that area?

[JUMAS]

The clamp could be leaking, but it would be unlikely if it's never been tampered with. many have reported the bolt backing out, usually after a DP install

[lwgrenier]

Originally Posted by JUMAS

The clamp could be leaking, but it would be unlikely if it's never been tampered with. many have reported the bolt backing out, usually after a DP install

I have a stock DP. As far as I know it’s never been touched. I’m getting the car inspected on Friday and was going to have my mechanic take a look, however I’m not sure how much digging he’ll have to do given that I have an Xdrive.

[JUMAS]

Originally Posted by lwgrenier

I have a stock DP. As far as I know it’s never been touched. I’m getting the car inspected on Friday and was going to have my mechanic take a look, however I’m not sure how much digging he’ll have to do given that I have an Xdrive.

Wish i could answer, but I can tell you for a fact the DP clamp can be seen through the passenger wheel well with the wheel removed. So I can only assume it should be similar for the xdrive.

ps. Good job taking it somewhere, I'm trying to decide when I want to curse the world for two hours and put my stock DP back in. lol

[weehe126]

Very unlikely that you would have a leak there. The intake can cause a decent amount of sound over the turbo. Might want to just double check it all.

[cahme]

Originally Posted by lwgrenier

Does anyone know if leaks between the turbo and downpipe are common on our cars? Ive been getting a lot of strange whirring noises on top of the additional turbo noise at all rpms lately. It seems like the n55 turbo is pretty robust so I’m hoping it’s not the actual turbo going. I’m also not hitting boost targets which could partly be a result of a leak in that area?

Even if there is a leak between turbo & DP, it wouldn't contribute to a boost leak.

I'd closely inspect the piping from the turbo to the intake. If you really think it's coming from the turbo, you can check the diverter valve ... Mine was blown:

http://www.e90post.com/forums/showthread.php?t=1289466

[lwgrenier]

Originally Posted by cahme

Even if there is a leak between turbo & DP, it wouldn't contribute to a boost leak.

I'd closely inspect the piping from the turbo to the intake. If you really think it's coming from the turbo, you can check the diverter valve ... Mine was blown:

http://www.e90post.com/forums/showthread.php?t=1289466

I will do that. I know I hadn't been hitting targets even before this new sound popped up which is like a lower pitched turbo noise. I was thinking maybe it was from the hot side of the turbo. Also if I'm in a low gear it will feel like the car is in limp mode until about 2.5k rpm and then I'll hear the turbo and power will be back. So I was thinking maybe the exhaust was leaking and not powering the hot side of the turbo at the lower rpms. No clue though. Does that sound similar to your diverter valve issue at all?

[cahme]

It's very hard to describe sound in text over the internet ... Essentially, it sounded like a boost leak coming from the 0assenger side. Also the boost built up pretty slowly too. I'll try to dig up an old log from when I had the leak and post it here..

As far as the scenario where it feels like no boost until 2500 rpm, that sounds more as if the wastegates aren't closing and may be
pressure control valve (boost solenoid) related. This wouldn't sound like a boost leak though and should result in underboost codes (2c57?)

[lwgrenier]

Originally Posted by cahme

It's very hard to describe sound in text over the internet ... Essentially, it sounded like a boost leak coming from the 0assenger side. Also the boost built up pretty slowly too. I'll try to dig up an old log from when I had the leak and post it here..

As far as the scenario where it feels like no boost until 2500 rpm, that sounds more as if the wastegates aren't closing and may be
pressure control valve (boost solenoid) related. This wouldn't sound like a boost leak though and should result in underboost codes (2c57?)

Yeah I'll start with just making sure all the intake piping is secure. I'm just taking shots in the dark at this point. It's crazy how many things can affect boost on these cars.

[shadow191]

If it's leaking from the turbo to downpipe, you could probably smell it in the engine bay since that's pre-cat. I had an N54 but when I had a loose v-band, the fumes got pretty strong. It was obvious there was a leak.

[lwgrenier]

I took my car in for inspection and they said the "band clamp that holds the turbo to the exhaust manifold was loose." Does anyone know if the downpipe clamps are accessible without dropping the subframe for an XDrive?

[weehe126]

Originally Posted by lwgrenier

I took my car in for inspection and they said the "band clamp that holds the turbo to the exhaust manifold was loose." Does anyone know if the downpipe clamps are accessible without dropping the subframe for an XDrive?

Depends on how it is positioned. Jack the car up and take a look.

[lwgrenier]

Havent been able to check the turbo to downpipe connection cause my closest friend with a garage is an hour away. I have three new codes:

2cf4: Oxygen sensor before catalytic converter, dynamics: slow response.
387f: power management: standby current violation.
2d2f: oxygen sensor before catalytic converter: multiple fault. (Hidden)

I think the first and third code could be a result of a leaking connection but not sure. Either way confirms something is going on around the downpipe. Have no idea what the second code is from... maybe they’re all tied together?

[weehe126]

first and third code say bad O2 sensor.

[lwgrenier]

Originally Posted by weehe126

first and third code say bad O2 sensor.

Do you think it’s definitely that? Could it possibly be the o2 sensor is reading abnormal values because of a leak and therefore throwing a code? It’s not triggering a CEL which is odd.

[weehe126]

99.9% bad O2 sensor. The first code pretty much means bad sensor.