BMW 335i running rough low boost.
 

Hi guys! I just registered on here. I'm at my wit's end with this car��



I have a 2008 BMW 335i E90

The only mods is an aftermarket charge pipe. I have had all vacuum lines replaced. New throttle body assembly unit. New water pump. New boost solenoids from Germany however I think my car runs slightly better with my old solenoids!? Intermittently my boost would come back and exhaust note would go back to being how it's supposed to sound for maybe 5 minutes before going back to being rough and no boost.

Ive had the car for 6 months and maybe two of those days I've enjoyed the car.

Funnily enough my problems stated after running 98 octane. My car has never been the same.

List of symptoms

- Car is starting to skip and vibrate when idling. Idling slightly rough. Popping from the exhaust. Almost like a misfire.

- Absolutely awful fuel economy

- exhaust note sounds raspy and God awful. Almost like a Civic with a fart can .

- Engine sounds like a bus. I can't really explain it but it sounds like it's not running on all cylinders.

- Almost zero boost. Lost all torque and incredibly slow to spool.

- Blowing white smoke randomly

- lots of black soot on my exhaust.

- Bad wastage rattle

Ive taken it to numerous mechanics. They all tell me the car isn't boosting and running rough because I need to install an X pipe on the exhaust so the turbo's flow better ��

Another mechanic acknowledged I'm severely down on power and wastegate could be stuck open.

Do you guys suggest I invest in a MHD app to check logs?

Any help would be appreciated.

???

Between slow spool, no boost, black soot, rattle, and white smoke it sounds like your turbos are done. Hard to say for sure without seeing/hearing the car in person or more data, though.

How do the turbos sound? Can you hear them? Might not be as easy to tell without intakes and ***.

Anyways, I went through a few sets of OEM turbos and can't say I ever noticed any of the idle, exhaust sound, or other symptoms you're mentioning. That's my only hesiation to turbos and wondering if there's another issue or a combination of things.

Thanks for the reply mate!

The only time I can slightly hear the turbo's is when the car is cold. After 5 minutes of driving the car sounds like it's Naturally Aspirated.

Absolutely. To answer your other questions. Yes, data-logs would be helpful here. However, any stored DTC's would be great.

If you want MHD tunes in the future then it can't hurt to get the cables and logging capability. However, a cheap $30 code scanner may be of use too. Would be great to see any fault codes, but even better to see any fault codes + logs.

I'd still lean towards turbos, unfortunately. Low boost and slow spool could be a boost leak. Add in soot & white smoke and that means you're likely burning some oil. Then the rattle. All of that added together tells me there's a shot turbo.

Poor fuel economy and rough idle are common symptoms of leaking injectors. Could be as simple as spark plugs and/or ignition coils. Otherwise, the odd exhaust sounds seems like an exhaust leak somewhere. Loose ********* or fittings elsewhere.

All of these things popping up at the same time seems unlikely, but I'm struggling to think of any 1 single issue that would lead to all of your stated symptoms.

Really appreciate your reply mate. I'm going to purchase MHD app and upload some logs on here. I have no idea how to read logs so I might need a hand lol.

The car is running super rough!! Zero power!