E90Post
 


TNT Racewerks
 
BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > How to Diagnose Boost Leak on Stock Parts?



Reply
 
Thread Tools Search this Thread
      02-24-2015, 10:48 AM   #1
NoTempoLimitN54
Second Lieutenant
NoTempoLimitN54's Avatar
United_States
3
Rep
256
Posts

Drives: E92 335i
Join Date: Sep 2012
Location: Los Angeles, CA

iTrader: (1)

Garage List
How to Diagnose Boost Leak on Stock Parts?

My '09 N54 335i is stock. Getting ready to start the tuning process in the next few months.

I did WOT on the freeway on-ramp and some short pulls on the freeway last night at 50F ambient. My P3Cars gage showed that the boost didn't even get up to 7 psi. Max was about 6.8/6.9.

This is with a gallon of E85 added to about 3/4 tank 91 AKI. Based on my calculations, the blend is E10-E12 and this should result in 92-93 AKI. For those that don't know, CA 91 AKI is E 5.7

I've had the gage on the car for over a year. I normally get 8 psi when running E10. My car is just short of 6 years and 72k miles.

Could I be leaking boost from either the stock DV's or the stock charge pipe? Is there a way to confirm that?

Thanks!
__________________

2009 335i 6MT (E92/N54), Black Sapphire / Shadowline (Individual 760) / Black Dakota Leather, ZSP, ZCW, 6FL, PDC, no Nav/iDrive, 19 x 8.5 / 19 x 9.5 VMR VB3 in Hyper Black, Pilot Super Sport 235/35 fr 265/30 rr, M3 control arms + tension links (fr)
Appreciate 0
      02-24-2015, 12:38 PM   #2
gtaccord
Major
United_States
18
Rep
1,230
Posts

Drives: 2009 BMW 335xi
Join Date: Feb 2012
Location: Maryland

iTrader: (7)

Garage List
A boost leak that large would register a code. Did you have traction control fully on?
Appreciate 0
      02-24-2015, 12:57 PM   #3
wgknestrick
New Member
6
Rep
19
Posts

Drives: 2011 335 xdrive
Join Date: Dec 2014
Location: Lancaster PA

iTrader: (0)



Make a boost leak test fitting. Need a hose coupler, clamps, plug, pressure gauge, and schrader valve. Use air compressor to boost it up to 20psi, and then spray soapy water over every joint. Bubbles are leaks. Just note that some air will likely leak through piston rings/valves, so it won't hold pressure forever. You'd be surprised how leaky the silcone couplers are if you don't test them.

Biggest source of leaks has always been textured powder coating on IC piping IMO. It's better to have smooth (non-powder coated) surfaces under hose couplers. Make sure you are using T-bolt clamps everywhere, (And not those crappy worm gear clamps shown in the picture). I just found that pic on the internets.
Appreciate 0
      02-24-2015, 01:19 PM   #4
gtaccord
Major
United_States
18
Rep
1,230
Posts

Drives: 2009 BMW 335xi
Join Date: Feb 2012
Location: Maryland

iTrader: (7)

Garage List
Quote:
Originally Posted by wgknestrick View Post


Make a boost leak test fitting. Need a hose coupler, clamps, plug, pressure gauge, and schrader valve. Use air compressor to boost it up to 20psi, and then spray soapy water over every joint. Bubbles are leaks. Just note that some air will likely leak through piston rings/valves, so it won't hold pressure forever. You'd be surprised how leaky the silcone couplers are if you don't test them.

Biggest source of leaks has always been textured powder coating on IC piping IMO. It's better to have smooth (non-powder coated) surfaces under hose couplers. Make sure you are using T-bolt clamps everywhere, (And not those crappy worm gear clamps shown in the picture). I just found that pic on the internets.
His car is stock. Most of what you mention does not apply.
Appreciate 0
      02-24-2015, 03:21 PM   #5
Dmacc
Colonel
63
Rep
2,709
Posts

Drives: 2010 135i
Join Date: Mar 2010
Location: Nor Cal

iTrader: (1)

Quote:
Originally Posted by gtaccord
Quote:
Originally Posted by wgknestrick View Post


Make a boost leak test fitting. Need a hose coupler, clamps, plug, pressure gauge, and schrader valve. Use air compressor to boost it up to 20psi, and then spray soapy water over every joint. Bubbles are leaks. Just note that some air will likely leak through piston rings/valves, so it won't hold pressure forever. You'd be surprised how leaky the silcone couplers are if you don't test them.

Biggest source of leaks has always been textured powder coating on IC piping IMO. It's better to have smooth (non-powder coated) surfaces under hose couplers. Make sure you are using T-bolt clamps everywhere, (And not those crappy worm gear clamps shown in the picture). I just found that pic on the internets.
His car is stock. Most of what you mention does not apply.
Regardless it's still really good info. I've been dealing with boost leaks left and right on my fbo set up. I have anodized intercooler piping and can agree with everything mentioned.
__________________

thanks to MGallop
Appreciate 0
      02-24-2015, 05:05 PM   #6
Jeff@TopGearSolutions
BimmerPost Supporting Vendor
Jeff@TopGearSolutions's Avatar
United_States
285
Rep
19,342
Posts


Drives: C6 Z06, GSXR-750, 09 335i
Join Date: Dec 2008
Location: TopGearSolutions.com

iTrader: (32)

Send a message via AIM to Jeff@TopGearSolutions
There are only a few ways to confirm a boost leak.

Either by visual inspection: Obvious signs of cracks in vac lines, pipes or couplers or parts being physically detached or not squared up and tightened down fully.

or

Boost leak test: Applying air pressure to the cold side of the intercooler or cold side of intakes and raising the internal pressure of the system to about 15-20 PSI. A leak would expose itself after that. Generally you can hear it but on a small leak it may require a little bit of soapy water to find bubbles.

Boost Leak Test DIY

With a car like the OP's the first question I'd ask is if you ever replaced the vacuum lines? If not, you can start there as that is just good preventative maintenance regardless and can be done for under $20. Buy about 20 Foot of vacuum line at any auto parts store and replace each line one by one. They go from the turbo's under the engine cover and around to the intake manifold and DV area.

The above link also goes into how you can test the factory DV for a leak.

The boost leak test does require a large set up time so for most its overwhelming but it's the best way to find a leak all said and done. Otherwise if nothing is obvious you unfortunately need to start replacing parts.

A smoke test is no good because it doesn't pressurize the system. A smoke test would only find an obviously large leak. You need the extra pressure that boost pressure test creates as things expand under pressure. Certain rubbers, plastic and seals under pressure expand and only leak then whereas they may not appear to leak or be leaking under lower pressure or at normal atmospheric pressure.
Appreciate 0
      02-25-2015, 12:13 AM   #7
NoTempoLimitN54
Second Lieutenant
NoTempoLimitN54's Avatar
United_States
3
Rep
256
Posts

Drives: E92 335i
Join Date: Sep 2012
Location: Los Angeles, CA

iTrader: (1)

Garage List
Great info, thanks guys!

No codes. But I recently got the water pump, thermostat and 6 fuel injectors replaced under CPO. Afterwards I felt like there was more turbo lag. I read up on that software update that increases the lag. I contacted my SA and she said that my software was not updated.

Normally, on our crap ACN91 gas here, I normally only get 7 psi, but adding some 100 AKI, E85, or a combination of both (best result), I'll see 8 psi.

It's possible that the P3Cars gage sensor is not super accurate, but it would be accurate to ITSELF and I thought it was strange that I could only see 7 psi even though I was running 1 gal E85 in about 12 gals of 91 AKI.

wgknestrick, where are you attaching the device in your photo?

Thanks, Jeff, for the suggestion about replacing vacuum hoses. Anybody know where to get vacuum hoses that match the factory stuff (ID/OD, material quality, etc.)?
__________________

2009 335i 6MT (E92/N54), Black Sapphire / Shadowline (Individual 760) / Black Dakota Leather, ZSP, ZCW, 6FL, PDC, no Nav/iDrive, 19 x 8.5 / 19 x 9.5 VMR VB3 in Hyper Black, Pilot Super Sport 235/35 fr 265/30 rr, M3 control arms + tension links (fr)
Appreciate 0
      02-25-2015, 09:46 AM   #8
wgknestrick
New Member
6
Rep
19
Posts

Drives: 2011 335 xdrive
Join Date: Dec 2014
Location: Lancaster PA

iTrader: (0)

Unfortunately, I haven't done a boost leak test on my 335 yet.... as I haven't started heavily modding (N55 and have only owned it for 2 months). I'm just talking from 10 years of experience with Subarus across 3 different turbo, IC, and manifold setups that I fabricated. It still applies though.

Ideally, the best place is the turbo inlet because you test the "most". On these cars, that isn't an easy thing to get to....what is, right? Testing at the turbo compressor inlet(s) tests the compressor backplate seal(s), all couplers, IC, etc....the entire positive pressure system. I fixed leaks at just about every connection on my Subaru when I'd test.

You just need to decide what you are willing to do, to perform a test. My motto is anything worth doing is worth doing right. You wouldn't bungie jump and only test the line, but not test your harness, would you? So you take the easy road and test at the IC. Say, The test comes out fine. Is your system without leaks? You don't know that. Was it worth the time to get questionable results? Generally, if you (or someone else) touched it after the initial factory install, you should be testing it....if you think you have a leak, or just want piece of mind.

I can tell you from experience, that a car performs much better with much less lag without leaks. The turbo has to work much less to reach target boost on a system that isn't leaking. You will have a more responsive car that makes more HP.

The O-ring connections that BMW uses on a lot of the fittings work really well though, so I don't want to start paranoia here. However, all O-rings can become compression set over time and cause leaks. Just check to make sure they are still round in cross section and haven't developed flat spots (called "compression set" failure). If you have a car around 80K+ miles, It would be a good idea to replace all of them (Buna N rings are fine) when you have things apart. Orings are cheap from Mcmaster.

Don't get paranoid about this. If you have the traditional silicone couplers and clamps, those have a much higher potential to leak....If you have an aftermarket turbo and had everything off you car, etc. If you are still stock, just check the old faithful suspects visually. I will also say that most systems easily hold 10psi, but few hold 30psi without leaks. If you run high boost on your car, this is something to think about. I'd test to 30psi on my STI because I ran 24psi on 93oct.

As for the IC piping. If you have the textured powdercoating (usually black) on it (note it's powder coat, not anodized) you can remove it via a brass brush grinding wheel. Anodizing is smooth and completely different, not to mention rarely done on IC piping). You just need to remove the coating around the perimeter of the piping where you use the clamps on the couplers to get a better seal. You can leave an overlap so that the bare aluminum is not visible under the couplers.

I have about 3 different sizes of test fittings in my garage, but don't know what DIA the BMW turbos are, besides "tiny". We need to share/post this kind of information once you solve a problem. That way the next person can quickly solve their problem by reading the forum.

The Subaru network was/is so much more advanced than the BMW network....the reason is that people shared information, helped each other, and weren't total assholes 100% of the time. I swear it's 5-10 posts until a BMW thread turns into E-peen comparisons.
Appreciate 0
      02-25-2015, 10:02 AM   #9
NoTempoLimitN54
Second Lieutenant
NoTempoLimitN54's Avatar
United_States
3
Rep
256
Posts

Drives: E92 335i
Join Date: Sep 2012
Location: Los Angeles, CA

iTrader: (1)

Garage List
Great info, wgknestrick! Unfortunately getting to the turbine inlets on these cars would not be easy. Plus there are two, so you'd need to pressurize both at the same time.
__________________

2009 335i 6MT (E92/N54), Black Sapphire / Shadowline (Individual 760) / Black Dakota Leather, ZSP, ZCW, 6FL, PDC, no Nav/iDrive, 19 x 8.5 / 19 x 9.5 VMR VB3 in Hyper Black, Pilot Super Sport 235/35 fr 265/30 rr, M3 control arms + tension links (fr)
Appreciate 0
      02-25-2015, 10:36 AM   #10
wgknestrick
New Member
6
Rep
19
Posts

Drives: 2011 335 xdrive
Join Date: Dec 2014
Location: Lancaster PA

iTrader: (0)

Quote:
Originally Posted by NoTempoLimitN54 View Post
Great info, wgknestrick! Unfortunately getting to the turbine inlets on these cars would not be easy. Plus there are two, so you'd need to pressurize both at the same time.
I know access sucks....Like the worse setup of any turbo car. You would only need to pressurize one and plug the other though. They are connected. I speak from my perspective, N55, and sometimes forget yours, N54. I see how tight my car is and can't even fathom fitting yet another turbo and plumbing in the same space.

I still don't know why they put the hot side of the engine so close to the strut tower. The engine should be tilted toward the cold side, not the hot side...even better, no tilt at all like all other turbo I6s. I digress though.
Appreciate 0
      02-26-2015, 10:36 AM   #11
NoTempoLimitN54
Second Lieutenant
NoTempoLimitN54's Avatar
United_States
3
Rep
256
Posts

Drives: E92 335i
Join Date: Sep 2012
Location: Los Angeles, CA

iTrader: (1)

Garage List
Quote:
Originally Posted by wgknestrick View Post
I know access sucks....Like the worse setup of any turbo car.
I was thinking something like the BMS dual-cone setup. Remove the air box, cap off and pressurize both turbo inlet tubes. Assuming the turbo inlet tubes are well sealed. I'll be in a position to do something in a few weeks.

They tilted the I6 (15 IIRC), I think to make room for the big complex intake systems on the NA cars. Also makes it a little easier to service the valves and change out spark plugs.
__________________

2009 335i 6MT (E92/N54), Black Sapphire / Shadowline (Individual 760) / Black Dakota Leather, ZSP, ZCW, 6FL, PDC, no Nav/iDrive, 19 x 8.5 / 19 x 9.5 VMR VB3 in Hyper Black, Pilot Super Sport 235/35 fr 265/30 rr, M3 control arms + tension links (fr)
Appreciate 0
      02-26-2015, 01:42 PM   #12
Tiago@VRSF
BimmerPost Supporting Vendor
Tiago@VRSF's Avatar
United_States
145
Rep
8,630
Posts


Drives: E92 335i, F30 328i, F82 M4
Join Date: Dec 2007
Location: Hudson, MA

iTrader: (95)

Garage List
Send a message via AIM to Tiago@VRSF
The intake tubes will probably blow off the turbos. I generally lower the passenger side of the intercooler, lower the inlet and run it from there off a 90 degree coupler.
Appreciate 0
      02-26-2015, 04:21 PM   #13
wgknestrick
New Member
6
Rep
19
Posts

Drives: 2011 335 xdrive
Join Date: Dec 2014
Location: Lancaster PA

iTrader: (0)

Quote:
Originally Posted by Tiago@VRSF View Post
The intake tubes will probably blow off the turbos. I generally lower the passenger side of the intercooler, lower the inlet and run it from there off a 90 degree coupler.
I agree. Intake tubes are not designed to take pressure. Let me warn all you, right now. 20 PSI is nothing to take lightly either. When things pop off at these pressures, they do so violently and dangerously. Be cautious and safe when testing.

Like I said, the best place to test is the compressor inlet on the turbo housing. It's not easiest on our cars. You cannot test through inlet pipes because they will blow off at about 5-10 psi. I know that is not the answer you wanted.
Appreciate 0
      02-26-2015, 04:53 PM   #14
Jeff@TopGearSolutions
BimmerPost Supporting Vendor
Jeff@TopGearSolutions's Avatar
United_States
285
Rep
19,342
Posts


Drives: C6 Z06, GSXR-750, 09 335i
Join Date: Dec 2008
Location: TopGearSolutions.com

iTrader: (32)

Send a message via AIM to Jeff@TopGearSolutions
Quote:
Originally Posted by Tiago@VRSF View Post
The intake tubes will probably blow off the turbos. I generally lower the passenger side of the intercooler, lower the inlet and run it from there off a 90 degree coupler.
Yea, the guy who did the boost leak test via the intake tubes even said after 10 PSI they won't hold pressure.

They are not made to be pressurized and it's also important to note the rear turbo inlet is typically prone to falling off and can be a pain to get back on. Especially with folks who have wrestled with that rear turbo inlet before while installing intakes.

Best method is as you said, lower the passenger side FMIC and do the boost leak from the cold side of the intercooler.

Getting access to the turbo inlets direct is too hard on this car.

Quote:
Originally Posted by wgknestrick View Post
I agree. Intake tubes are not designed to take pressure. Let me warn all you, right now. 20 PSI is nothing to take lightly either. When things pop off at these pressures, they do so violently and dangerously. Be cautious and safe when testing.

Like I said, the best place to test is the compressor inlet on the turbo housing. It's not easiest on our cars. You cannot test through inlet pipes because they will blow off at about 5-10 psi. I know that is not the answer you wanted.
This is true. Even at 5 PSI you might be able to find a boost leak elsewhere though. So it's really up to the person doing the work if they want to go through the trouble or not with that method. They will never get to 20 PSi for sure with the inlet method.
Appreciate 0
Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -5. The time now is 03:20 PM.




e90post
e90post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2015, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST