[nicktyler]

So I have this pretty serious problem:

Got a limp mode when WOT which cut all boost. Took it to the garage and when restarted the exhaust was seriously loud, like rude boy Civic loud. the code was for low boost so thought it must be a boost leak as there was also a faint hiss from under the bonnet.

There is no boost leak and everything is connected properly. The car sounds like it has no exhaust and cuts boost to 0psi and throws low boost code at the first sign of any boost.

I am at a complete loss as to what the problem is and the garage is confused as well. It shows all the symptoms of being a boost leak but apparently it is not.

Any ideas?

Cheers

Nick

[Icekube]

not trying to be funny, but have you looked to see if the exhaust is attached correctly?

[nicktyler]

Yes. There is no boost leak and everything is connected properly.

The car sounds fine off throttle and idle is smooth.

[Icekube]

boost leaks would be inlet side, nothing to do with the exhaust

the exhaust being louder means that something from the hot side of the turbos to the back of the car is broken, be it a downpipe gasket, flexi pipe or something else

[nicktyler]

Doesn't explain the lack of boost and limp mode though.

The downpipe gaskets have been replaced less than a week ago. And replaced and checked again when this happened.

I think it could be this:

http://www.bmwland.co.uk/forums/view...9253&p=1152364

[Icekube]

it could be the wastegate (thats on the turbo hot side), and i would be a bit suspect if they failed so soon after having downpipe gaskets replaced...

has your car had the wastegates replaced by BMW previously? (http://www.e90post.com/forums/showthread.php?t=729833)

[nicktyler]

How do you mean suspect about them failing? I had them rebuilt by Essex Turbos less than a year ago. Then a couple of weeks ago had the car put back to standard to sell it, DP's and intercooler. Since then there has been no end of problems. Noisy turbos (siren). Post cat O2 sensor and now this.

It's a Fu**king nightmare and all I want to do is be rid of it.

[CustomColours]

Omg! Is eveeyone serious. A vacuum/boost leak can obviously cause a loud exhaust/open wastegate issue.

If you have a vacuum pipe split etc it can lead to the same issue. It loses the vacuum to control the boost of the car.

Check all vac lines, check charge pipe and lastly it could be your vac tanks or even boost solenoids. If all else fails you mite have a broken actuator or stuck wastegate.

[nicktyler]

All else has failed so far. Maybe I should get a second opinion. I was convinced it was a boost leak as it shows all the symptoms of that and the way it failed.

It's been in the garage 3 days so far and they can't find any leaks.

[idnan]

Originally Posted by CustomColours

Omg! Is eveeyone serious. A vacuum/boost leak can obviously cause a loud exhaust/open wastegate issue.

If you have a vacuum pipe split etc it can lead to the same issue. It loses the vacuum to control the boost of the car.

Check all vac lines, check charge pipe and lastly it could be your vac tanks or even boost solenoids. If all else fails you mite have a broken actuator or stuck wastegate.

Listen to this guy! Loud exhaust=open wastegate and that can be caused by vac issues etc

One question though, has it constantly got the limp mode light one whilst the exhaust sounds loud?

One potential unmentioned problem could be the downpipe to turbo clamps. If they replaced the turbo to downpipe gasket and didn't orientate the clamp in the right position, it is possible for it to interfere with the wastegate.

[nicktyler]

Originally Posted by idnan

Listen to this guy! Loud exhaust=open wastegate and that can be caused by vac issues etc

One question though, has it constantly got the limp mode light one whilst the exhaust sounds loud?

One potential unmentioned problem could be the downpipe to turbo clamps. If they replaced the turbo to downpipe gasket and didn't orientate the clamp in the right position, it is possible for it to interfere with the wastegate.

The limp mode is not there when you restart the car but the loud exhaust is allways there. So there is loud exhaust but no limp mode yes. It could be the clamp alignment but it worked fine for a good 60-70 miles and then suddenly went to limp mode.

[nicktyler]

Yeah so the wastegate arm is just dangling about on the front turbo not attached to the actuator anymore.

Great! That will be the 3rd rebuild within a year.

[///Mposter]

Glad you found out what it was. That waste gate arm uses a clip to hold it together. It should be an easy fix , besides the location of it. Best of luck.

[nicktyler]

Originally Posted by ///Mposter

Glad you found out what it was. That waste gate arm uses a clip to hold it together. It should be an easy fix , besides the location of it. Best of luck.

Thanks for that info. I hope you are right!