[gsr]

Gents,
Need some help as to what the issue is with my 2007 335D.
Couple of months ago, I would be going along and had no boost at low revs. Higher revs above 3-3.5K was OK. Garage said the intercooler needed replacing and a few turbo pipes. Had the work done ~£1k.
Seemed to be OK until last night when the same thing happened. However this morning, all is OK again.
Can't be the low rev turbo or split pipes anywhere as it would be the same this morning. Could it be a valve that's intermittently sticking when hot or software issue?
Any advice would be greatly appreciated.
Thanks
Gordon

[e90Noobie]

Check/replace vacuum lines? They should be replaced anyways.

[_N54]

I went through this issue. Replaced all the lines and sensors just to be on the safe side and it didn't fix the problem. Ended up getting Tim's Stage 1 turbos and all my power is back if anything a bit more. My M57 was also deleted during the time of having no power. The small turbo was shot and it was also passing oil through the exhaust turbine. The car had absolutely no power or boost in first or second gear with a shit ton of black smoke and in third gear it would finally start to spool, but wouldn't move out as quickly as it does now.

[fearitself165]

I'm feeling as if mine is low on boost as well. I've only owned her about 5 months and if its something that seems to occur slowly over time then I often don't notice. I wonder if that's common with others?

I just remember the feeling when I got the high pressure small turbo boosting again how "quick" the car felt. Lately its been feeling just like a naturally aspirated car almost. Recently I replaced all the vacuum lines except the piece that goes right under the low pressure turbo area, and the piece that goes up to connect to the driver's side engine mount. I do plan on replacing these eventually though.

I have no codes so I'm wondering if this is still related to vacuum. Will a vacuum problem be noticeable even if its some other issue causing the low boost? Because if so then I feel like mityvac is the best option for me and possibly the OP.

[turbotel]

Replace MAF.

[lnxguy]

Originally Posted by turbotel

Replace MAF.

He'd have no power on the top end if the MAF was bad.

OP needs to check a few things.

1) Vac lines
2) Pressure convertors and EV valve
3) Actuator for turbine switchover
4) Actuator for compressor bypass
5) Actuator for wastegate.

[gr8whte]

+1 on MAF sensor
Had same issue. Underpowered with lots of black smoke. Intermittently though. After I had already replaced all the vacuum lines and actuators. No codes. It was MAF. The difference was night and day.

[Staynspool]

Hey Guys. I am in the same boat here and cant seem to make any headway. I have barely any power until the LP turbo kicks in and it still seems to not have full power. I have no codes showing. Car is a 2010 335d deleted and tuned, DP & straight pipe exhaust, upgraded FMIC, stage 2+ tune from BPC, ATM intake, trans tune and upgraded red boost pipe (forge) as I did it awhile back. Car has 133K miles and it has been tuned and deleted since 38K miles. I started down the vacuum leak road and replaced everything including new vacuum reservoir, pressure convertors, turbo actuation switch under the reservoir, both motor mounts, and all vacuum lines. I t-d a mighty vac gauge into the vacuum lines while running and the car holds 25-26 Hg. I manually checked vacuum on all new components including the wastegate and bypass valve in addition to verifying all the vacuum line routing with no avail, all is good. Am i missing something or is the small turbo shot? I also replaced the MAF sensor and the absolute pressure sensor. I am getting good readings with all sensors through my schwaben scan tool when i monitor the live data but the car will just not make power down low and throws a ton of fuel out the back to the point that people think im rolling coal on them on purpose. I will say that the throttle response and power did increase slightly after all the vacuum shenanigans so I must have been loosing some through old lines and one of my motor mounts did look partially collapsed when I changed it out.

[cr1do]

Best of plug it in and see if it throws any codes then take some logs while at it

[lnxguy]

Originally Posted by cr1do

Best of plug it in and see if it throws any codes then take some logs while at it

It won't throw any codes if it's BPC tuned, lol.