Last summer before I attempted to sell my 335xi, I noticed an ever so slight change in the tenor of its whooshy turbo noises. I thought it might’ve been a boost leak and/or a slowly dying diverter valve. I had my mechanic check it out but they gave it the all clear. I chalked it up as one of those changes that only an OCD car owner would notice, and decided to wait until the problem became more noticeable.
In the past couple weeks, my diverter valve has become straight up busted. It makes this definitely broken-sounding noise if I request a halfway decent amount of boost with the loud pedal, and the motor feels down on power when this noise occurs. This morning it happened again and I got a mass air flow CEL code which I assume is related.
Since I paid off the car instead of selling it, I of course will fix it, which means it’s time to replace the shitty OE BMW diverter valve with a GFB DV+. Also, while I’m doing this, I’m going to replace my crappy plastic OE turbo outlet pipe with this metal one from VRSF.
All my other charge piping is aftermarket metal stuff with silicone couplings, but VRSF hadn’t yet started making this turbo outlet when I did my bolt-ons, so I reused the OE plastic turbo outlet.
I’m not going to do a new water pump, which is often done when doing the diverter valve as they’re in the same general area and you have to partially relocate but not disconnect the water pump to get at the diverter anyway. But my car got a remanufactured motor back in 2016 which included a fresh water pump.
After this, I will have a fully reliable BMW, because everything that could’ve broken will have been replaced. At least until the next thing breaks.