135i Turbos not building boost

SNDWCH36 · 05-30-2022, 08:08 AM

Hello all,
I bought a BMW 135i convertible (N54, 2008, 150,000km US model) about a month ago. Unfortunately, it' s been giving me problems for a few days now and I hope someone has another idea, I' m running out of ideas.

About the problem:
I drove the car home last week in the evening about 40km, (very calm, not sporty), had no problems everything ran perfectly and parked the car in the garage at night. The next morning I got in, briefly let it warm up and wanted to drive to work.
At the first slight acceleration I noticed that the normal "turbo noise" is about 3-4 times louder than the night before. I then drove carefully until everything is at temperature, accelerated a little harder and the noise was again significantly louder the higher the engine turns. In addition, the car has significantly less power.

What I have already checked since then:
Checked all hoses and connections in the boost air circuit and vacuum circuit, everything looks good (No cracks, connectors all tight).

Replaced the boost control solenoid valves, no change.

Lifted the car on a lift and checked the wastegates, both move in one direction when starting the engine and back again when turning off, rods can be moved by hand with some force against the spring (not stuck)

With MHD software recorded the boost set point and actual value, set point when accelerating around 16psi, actual value reaches maximum 1.5 psi and does not increase further, while you hear the turbos extremely loud however.

Fault log code "30ff boost pressure too low".

made a smoke test with a "fog machine", a lot of smoke came out at the "twisting ports" of the 2 boost bypass valves on the chargepipe.... sealed as good as I could with many layers of tape, hardly any smoke comes out, still no improvement boost pressure does not rise above 1.5 psi. (Nevertheless, I have ordered an aluminum chargepipe as a precaution, which should generally withstand the higher boost pressure better and the OEM valves are then attached with hose and hose clamps so 100% sealed).

Mods are a larger intercooler, downpipe, exhaust system and software Stage 2 from the previous owner, turbos were completely replaced about 2 years ago with new OEM parts.

joeo · 06-01-2022, 08:14 AM

May want to build a boost leak detector so that you can pressurize the intake and check for leaks.
I had this happen recently and it was a blown up turbo (rear), but in my case, it would make 0 psi. In your case, to me, it really seems like a leak.
If you log waste gate duty cycle, you can at least check to see if the computer is trying to make boost.

-Joe

Afam28 · 06-18-2022, 09:29 PM

Sounds a charge pipe related boost leak…
Are your boost solenoids genuine BMW?

05-30-2022, 08:08 AM	#1
SNDWCH36 Registered 0 Rep 1 Posts Drives: BMW 135i E88 Join Date: May 2022 Location: Germany iTrader: (0)	Hello all, I bought a BMW 135i convertible (N54, 2008, 150,000km US model) about a month ago. Unfortunately, it' s been giving me problems for a few days now and I hope someone has another idea, I' m running out of ideas. About the problem: I drove the car home last week in the evening about 40km, (very calm, not sporty), had no problems everything ran perfectly and parked the car in the garage at night. The next morning I got in, briefly let it warm up and wanted to drive to work. At the first slight acceleration I noticed that the normal "turbo noise" is about 3-4 times louder than the night before. I then drove carefully until everything is at temperature, accelerated a little harder and the noise was again significantly louder the higher the engine turns. In addition, the car has significantly less power. What I have already checked since then: Checked all hoses and connections in the boost air circuit and vacuum circuit, everything looks good (No cracks, connectors all tight). Replaced the boost control solenoid valves, no change. Lifted the car on a lift and checked the wastegates, both move in one direction when starting the engine and back again when turning off, rods can be moved by hand with some force against the spring (not stuck) With MHD software recorded the boost set point and actual value, set point when accelerating around 16psi, actual value reaches maximum 1.5 psi and does not increase further, while you hear the turbos extremely loud however. Fault log code "30ff boost pressure too low". made a smoke test with a "fog machine", a lot of smoke came out at the "twisting ports" of the 2 boost bypass valves on the chargepipe.... sealed as good as I could with many layers of tape, hardly any smoke comes out, still no improvement boost pressure does not rise above 1.5 psi. (Nevertheless, I have ordered an aluminum chargepipe as a precaution, which should generally withstand the higher boost pressure better and the OEM valves are then attached with hose and hose clamps so 100% sealed). Mods are a larger intercooler, downpipe, exhaust system and software Stage 2 from the previous owner, turbos were completely replaced about 2 years ago with new OEM parts. Attached Images
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06-01-2022, 08:14 AM	#2
joeo Lieutenant 120 Rep 475 Posts Drives: 2009 Crimson Red 135i Join Date: Mar 2008 Location: Sterling, Va iTrader: (0) Garage List 2009 BMM 135i [9.50]	May want to build a boost leak detector so that you can pressurize the intake and check for leaks. I had this happen recently and it was a blown up turbo (rear), but in my case, it would make 0 psi. In your case, to me, it really seems like a leak. If you log waste gate duty cycle, you can at least check to see if the computer is trying to make boost. -Joe
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06-18-2022, 09:29 PM	#3
Afam28 User 298 Rep 775 Posts Drives: 2008 BMW 135i M-sport Join Date: Apr 2018 Location: MD. iTrader: (1)	Sounds a charge pipe related boost leak… Are your boost solenoids genuine BMW?
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