Hello all,

My 2009 R55s has the above issue going on. Was driving last weekend and let off throttle (to hear turbo whooshes) and heard more of a pop than whoosh. Immediately the reduced engine power notification came on the tach (yellow not red thank goodness) and no boost being generated nor heard or felt. Luckily was a mile from home and got it right in my garage.

So...what could it be? No CEL to pull a code, but still reduced power after letting it sit off the battery for a few days. My OBD iOS app shows no boost being made. I've checked plugs and vacuum lines on the pressure converter and diverter valve. I started the engine briefly without the inlet pipe on, and the turbine spins, so nothing seized up mechanically.

If anyone has any additional troublehooting, I'm up for it.

 

Sounds like it might be the BOV/Diverter valve or the waste gate. There's a little diaphragm in the stock Diverter that could have broken. As it sounds like the turbo works, so I'd think that there's something with intake side, and that would be the diverter, You might have also blown the seals in the cassette and it could be spilling out that way. Though I'd start with pulling the diverter and checking to see if the assembly in in tact. Bimmerdude on youtube has a video on it if memory serves.

 

Following for info

do you have any strange fuel trim readings?

Does your exhaust smell rich or lean?

Ive got a similar issue on my 09 r56 but after a while I got a cel for too rich at idle and too lean off idle.