I have a 2007 r56s and please forgive me this is my first turbo car and i'm not that versed in how it all works. I just had my timing chain tensioner replaced ( I had the first signs of rattle ). I was a few miles down the road when the boost cut out mid acceleration and the service light came on. When i opened the hood the large air hose behind where the tensioner is had come out because they put the metal retaining clip back on incorrectly. When this happened it destroyed the rubber o ring that seals where the two sections join (I retrieved the seal it did not drop down the intake). Would the lack of this seal be enough of a leak to cause complete lost of boost and mimic a failed MAF sensor?

 

I have a similar problem. I've Just had the relevant tensioner bits replaced. 3 weeks after i now i have what feels like no boost at high acceleration accompanied by a wierd hissing noise (sounds like my heating is turned up on full, it stops as soon as i lift off the power) i have definite power loss, but no CEL lights. I'm going to check all my hoses tomorrow to see if anything is loose. Did reconnecting the hose fix your problem?

 

yes..i ended up finding an o-ring that fit on there and I also found several other loose hoses. Correcting them fixed the issue with the power loss. It didn't correct my idle issues though. Turned out carbon build up had cause one valve to bend and another to crack.

 

The carbon build up is an absolute nightmare on these DI engines. I did a water decoke today to see if it helps with the carbon problem... I think i need to double check all my hoses for the powerloss

 

they tried a chmical decoke on mine. The build up was too much for it to have any effect. When the head came off to replace the valves they manually cleaned all the carbon and used a solvent to clean the cylinders and top of the pistons. The new valve cover has greatly reduced the amount of oil feeding through the rear pcv hose so hopefully it will help prevent a future issue.