I've tried everything, still underboosting!

Rem_F30 · 08-20-2018, 05:29 AM

I'm seriously stumped. I'm on a E40 mix with Pure Stage 2s targeting 20psi. I'm only able to hit roughly 16-17ish psi.

Mods:
Riss Racing downpipes
Bms intakes
Vrsf charge pipe w tial bov
Vrsf inlets
Ps2
No name 5" fmic
Xhp stage 3

I've done the following:

Replaced charge pipe O ring
Replaced intake manifold gaskets
Replaced all vacuum lines
Replaced boost solenoids
Replaced valve cover gasket

I even pressurized the system to 20psi (tried to at least). It will go up to 16-17psi before hanging but if I hold it for a while it will go past it.

The catch is that I can hear somewhere still leaking but I've literally spent days trying to find it. It honestly sounds like its coming from inside the motor. You can hear a very small hiss near the valve cover and if you put

your ear on it it sounds like it's inside. (Note: when I pressurized the system I did cap off the pcv return).

Rear inlet is on good & front inlet as well...all t clamps are bolted down good (thanks to the pressure test there was 5 areas that I found were leaking)

Any other ideas?

tisdrew · 08-21-2018, 04:49 PM

Smoke test it?

srey · 08-21-2018, 05:17 PM

Try pressure testing it from the hot side of the intercooler leaks in the inlets dont matter as much. You'll be better able to pinpoint a leak, if any, that way. How are your intercooler coupler o rings?

Jeff@TopGearSolutions · 08-21-2018, 06:24 PM

Quote:

Originally Posted by srey

Try pressure testing it from the hot side of the intercooler leaks in the inlets dont matter as much. You'll be better able to pinpoint a leak, if any, that way. How are your intercooler coupler o rings?

I was going to say this also. The system should be pressurized from the hot side of the FMIC, OP?

mojobmw_e90 · 08-21-2018, 06:49 PM

Check o ring on maf sensor on charge pipe

feuer · 08-21-2018, 09:25 PM

Tried everything except:
-seals on IC
-seal on CP
-orings on sensors
-adjusting wastegates
Check these and let us know.
Also, if on original turbos form 07 that probably have over 100k expecting 20psi is little too optimistic

Aceway · 08-22-2018, 09:20 AM

Check the meth bung plugs on chargepipe. Both of my plugs fell out within a few months and I was underboosting 1-2 psi.

BourneJack · 08-22-2018, 09:26 AM

Quote:

Originally Posted by Aceway

Check the meth bung plugs on chargepipe. Both of my plugs fell out within a few months and I was underboosting 1-2 psi.

+1

08-20-2018, 05:29 AM	#1
Rem_F30 New Member 2 Rep 10 Posts Drives: White 2007 N54 E92 Join Date: Mar 2018 Location: Hesperia iTrader: (0)	I've tried everything, still underboosting! I'm seriously stumped. I'm on a E40 mix with Pure Stage 2s targeting 20psi. I'm only able to hit roughly 16-17ish psi. Mods: Riss Racing downpipes Bms intakes Vrsf charge pipe w tial bov Vrsf inlets Ps2 No name 5" fmic Xhp stage 3 I've done the following: Replaced charge pipe O ring Replaced intake manifold gaskets Replaced all vacuum lines Replaced boost solenoids Replaced valve cover gasket I even pressurized the system to 20psi (tried to at least). It will go up to 16-17psi before hanging but if I hold it for a while it will go past it. The catch is that I can hear somewhere still leaking but I've literally spent days trying to find it. It honestly sounds like its coming from inside the motor. You can hear a very small hiss near the valve cover and if you put your ear on it it sounds like it's inside. (Note: when I pressurized the system I did cap off the pcv return). Rear inlet is on good & front inlet as well...all t clamps are bolted down good (thanks to the pressure test there was 5 areas that I found were leaking) Any other ideas?
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08-21-2018, 04:49 PM	#2
tisdrew First Lieutenant 98 Rep 300 Posts Drives: 2009 335i Join Date: Dec 2015 Location: Melbourne, FL iTrader: (0)	Smoke test it? __________________ "Wheels and exhaust aren't a build"
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08-21-2018, 05:17 PM	#3
srey Lieutenant 224 Rep 418 Posts Drives: 2007 E90 335i 6mt Join Date: Jun 2017 Location: Idaho iTrader: (0)	Try pressure testing it from the hot side of the intercooler leaks in the inlets dont matter as much. You'll be better able to pinpoint a leak, if any, that way. How are your intercooler coupler o rings?
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08-21-2018, 06:49 PM	#5
mojobmw_e90 Major 382 Rep 1,497 Posts Drives: 2014 E63S Join Date: Oct 2014 Location: Chicago IL iTrader: (3)	Check o ring on maf sensor on charge pipe
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08-21-2018, 09:25 PM	#6
feuer Major General 4289 Rep 9,226 Posts Drives: wife crazy! Join Date: Apr 2015 Location: Chicago, IL iTrader: (5)	Tried everything except: -seals on IC -seal on CP -orings on sensors -adjusting wastegates Check these and let us know. Also, if on original turbos form 07 that probably have over 100k expecting 20psi is little too optimistic
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08-22-2018, 09:20 AM	#7
Aceway Captain 460 Rep 875 Posts Drives: E82 135i / F25 28i Join Date: Feb 2018 Location: SoCal iTrader: (2)	Check the meth bung plugs on chargepipe. Both of my plugs fell out within a few months and I was underboosting 1-2 psi.
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