BMW N54 30FF Underboost Code – Boost Leak Testing – DIY

We decided to share this great DIY on boost leak testing that was contributed to the N54 community a long while back and is still very useful for those running into issues with underboost codes, limp mode due to a boost leak in their charge piping.


Spent a lot of time the past week trying to diagnose a 30FF. (Boost Log is NOT matching Target)
Since 30FF can be from a leak in the pressurized section of the intake track and/or the turbo just isn’t putting out enough, I broke this up into 2 areas:

1. Turbo compressor (COOL side) to intake manifold/head interface.

a. Test entire intake system.

b. Test Diverter Valves

2. Turbo compressor operation(HOT side) –

a. Vacuum system & line integrity

b. Wastegate actuator & line integrity

c. Solenoid functionality

The sequence of the tests is not so important. You can start with the tests you already have the tools or time for and stop if you are lucky enough to detect & fix the problem. Just remember that there can be more than 1 source for the 30FF. You’re not done till the 30FF’s stop popping up.

OK, I had already made several fittings to tap into, plug and pressurize sections of the OEM intake system.
After removing sections of the intake system and checking them independently, it was obvious they could leak when they were put back together.
So after playing with all the new gadgets I wanted to test the system w/o removing any parts that are exposed to boost pressure.

Step 1a Tools & Equipment
• Compressor w/ regulator, GOOD pressure gauge, hose
• Very quiet garage to listen for leaks – beware of neighbors watering the lawn
• Squirt bottle w/ Dish soap & water
• (2) – 1-1/2” PVC pipe cap ($0.77 each @ Menards)
• (1) – ¼” NPT male hose fitting ($0.25 @ Harbor Freight)

Prep work:
Remove any bumps (injection molding gates) on the OD of each cap w/ a file (if necessary, depending on mfg.). Make it smoothed.
Drill & tap 1 cap to install air fitting. (7/16” drill, ¼” NPT tap)

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Get front wheels off the ground – ramps, jack stands or lift
Car off and cool
Remove the 14 screws & engine splash pan
Remove the DCI’s (or air filter box) to access the 2-1/4” accordion intake tubes.
Install plain PVC cap in the F tube and the other cap w/ air fitting into the R tube and tighten hose clamps.
**If running OEM crankcase venting system you must Plug the rear air intake tube at the PCV return tube heater element**-edit on 8/25/11
Set the air pressure regulator to ZERO and connect air hose to cap fitting.

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You are now “in Theory” ready to pressurize the whole intake & exhaust system from the air inlet to exhaust tips. Not sure why but didn’t need to use exhaust tip plugs I made cause air was not exiting the exhaust. Only thing that comes to mind is no overlap between intake & exhaust valves. Ideas welcome…

SLOWLY increase regulator air pressure to 10 psi (it’s high enough to find a pretty small leak).
Filling up the whole system takes some time and can sound like a leak when filling. Give it time & let pressure stabilize.
The air intake tubes are not designed to hold pressure but they do hold some. Mine held to 12 psi B4 rear turbo inlet started hissing. This is NOT a boost leak but the weakest joint in this test method.
Don’t go leak hunting if a turbo inlet is leaking @ 10 psi. You may need a buddy to hold intake tube onto turbo @ 10 psi if leaking there or get creative and wedge it in place.

Reference Picture from Hotrod’s post, I did NOT remove my engine!
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Listen & look, squirt soapy water anywhere/everywhere you suspect & look for bubbles to confirm leak. Get under the car & check both turbo connections, piping, connectors, FMIC, elbow, DV or BOV & recirculation tubes, vacuum/boost lines to DV’s, Charge pipe, Throttle body, intake manifold to engine head. Fix any leaks & retest. If air tight @ 10psi you are done with this step.

Here’s what I found!

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Step 1b.Test DV’s

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I also rigged up a way to pressurize the DV’s , CP & elbow as an assembly. Used syringe w/ Tee to both DV’s.

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Step 2a. Vacuum system & line integrity – Tools & Equipment
• Vacuum gauge
• Pick or small pry tool to remove vacuum hose

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Vacuum to Wastegate solenoids
Follow hose from the top a canister to a solenoid. Remove hose at the solenoid and connect vacuum gage. Start car, gauge should read about 26” Hg at idle. Don’t know acceptable limits but if it’s much lower than 26” trace ALL hoses all the way back to vacuum pump (behind oil filter). Replace leaking or pinched hose.
Reconnect the hose and repeat the vacuum test on remaining solenoid.

Step 2b. Wastegate actuator & line integrity – Tools & Equipment
• 100cc or larger syringe
• 5/35” Tee
• Towel Clamp or long nose vice grip

Test can be done w/o a Tee by connecting syringe directly to braided hose going to wastegate actuator. (Easier said than done)
Since a Tee is needed for Step 2C you can save time & aggravation if you:
Cut the 5” long hose that’s between the 2 OEM tees (see below)
Use clamp to Pinch the short hose that runs down from the Rear Tee to the Rear Solenoid
Connect syringe to the Hose you just cut
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Apply vacuum by pulling syringe plunger and check for smooth movement of actuator rod and a metal to metal sound when the wastegate closes.
Once wastegate is closed it must remain closed and the force needed to hold the plunger steady must remain constant. If it gets easier to hold the plunger in place it means the hose and or actuator is leaking.
Repeat for front actuator connecting syringe to remaining 1” of OEM tube & pinching front line between Tee to Solenoid. The front actuator that is NOT visible from above engine. If you don’t have access to a borescope to watch the rod movement, listen closely to the sound and compare to the front. If you can’t see the actuation rod you will have to make the call (by listening) if it’s operating like the rear actuator.
Connect Tee and go to next step or plug the open end of the Tee if you are done.

Step 2c. Solenoid Functionality – Tools & Equipment
• Vacuum gauge
• 6’ of 5/32” vacuum hose
• 5/32” Tee ( if you didn’t take my advice in 2b)

Install 5/32” Tee into vacuum hose you cut in 2b.
Connect 6’ hose to Tee & gauge
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Route gauge thru drivers window & into car
Getter warmed up, cruse at about 60 mph in 3rd,
Go WOT, w/ a Tune the gauge should spike then hold at about 20” while under boost.

If the 30FF is not gone then there’s only 2 more options:
1. Wastegate rod adjustment back to OEM spec
2. New Turbos

Customer Review – Kline Decatted Exhaust Review 997.2 TURBO S

We wanted to share a recent customer review of a KLINE decatted exhaust on their Porsche 997.2 Turbo S and their comparison with a Europipe exhaust.

URL to a forum review:

Continue reading

534WHP 532WTQ – One-off set of custom turbos from Vargas – Race Gas + Meth – New N54 Stock Frame Turbos/Stock Motor Record? We think so..

Went back to the dyno this past Saturday. It was a lot hotter out than last time when the car did 523whp on pump+meth. With the same conditions as on the pump/meth runs it could’ve maybe done a touch better, maybe 540 even, maybe not. It shows just how close meth/pump numbers can be to a more expensive race gas+meth alternative when you’re already maxed on the turbo side of things. However, with race gas some additional timing managed to be had without knock through the top end helping power not drop off as quickly in the 6-7k rpm range.

These are the one-off set of stock frame upgraded turbos from Vargas. These will never see production and are not Stage 2 Batch 2 turbos. These have a one off housing that was used in the name of “science” to see the effects of a lot more machining work on the turbine housing when it comes to hp while preserving the OEM exhaust manifold in place.

This seems to be the new stock frame turbo stock N54 motor record, with a tune that was done in the most appropriate of ways possible (i.e. not testing hardware limits with bottom end boost or torque), even though its a hybrid of VTT/ASR hardware. The rpm/mph chart below the power/torque graphs is to show the RPM pickup cutting out Click here to enlarge dyno shop will need to sort that one out hopefully soon

GREEN line is pump/meth
RED/BLUE lines are race gas/meth

Both tunes run the same boost and wg duty cycles. Only thing remaining is to try maybe using an E85 blend with meth, possibly.

523WHP 520WTQ – BETA VTT Turbos – Pump gas and Methanol Injection

Had some fun with a set of BETA VTT Stage 2 turbos on Wednesday night and here are the numbers. The tune is running 21psi peak down low, 20psi at 6k rpm, 19psi at 6200rpm, 18psi at 6500rpm, 16.6psi at redline. Timing is in the range of 10.5 to 11.5deg peak without any hint of timing corrections all the way through.

This was on  pump 94 octane from Petro Canada (formerly Sunoco) running the Aquamist HFS-4 setup with two 1mm nozzles and 100% meth. According to short term trims the DME is pulling out 25% through trims with two 1mm nozzles so we could probably dial it in a bit better by dropping one of the two 1mm nozzles to a 0.9 or a .8mm instead.

Numbers look really nice and the most this car has ever made on pump and meth so far with this much timing and boost. Boost wise there isn’t any more to be had up top but we expect there’s possibly another 2-3 degrees left in there on race gas.

Design wise these turbos should be close to what the next Stage 2 Batch 2 setups end up looking like from Vargas Turbo Technologies. The actual Stage 2 Batch 2 dyno numbers will be published with our tuning once they’re ready and installed for testing on the the new VTT shop test car.

Custom single turbo – 18-18.5psi – external wastegate control, OEM solenoids, COBB flash only – shakedown runs

Wanted to share what I think is another key milestone in N54 tuning. Yesterday we managed to use Cobb to control an external Tial wastegate entirely, without piggyback involvement and make some good numbers. Boost control had to be redone from the typical way its done for internally wastegated vacuum operated turbos such as OEMs and any stock frame hybrids.

We stopped at these numbers as the HPFP pressure literally nosedived near redline to 600psi from 2000+psi targeted so we’ll be looking at the usual fuel capacity boosters and a couple things that I haven’t heard of being tried yet.

This was at 18-18.5psi peak. Timing is around 8-10.5deg, our Petro Canada (Sunoco) pump 94 octane. No idea at the moment how much more power is left on our pump gas but I bet quite a bit more as this was literally just getting started LOL

Exhaust manifold is very similar to FFTEC’s with the runners going up and merging down the middle to a T4 flange. GTX35R 1.06AR turbine housing, Tial wastegate with a 10lb spring. Exhaust is a single 3.5″ all the way back with the wastegate plumbed into the exhaust. This kit was a one off for a local car that has seen tons of 1/4 mile racing in the past and had one of the first RBs ever made. He drove the car on the street after, no issues, raced what looked like a 600 bike I think, stayed door to door…

The size of the exhaust housing is obviously making this a top end beast vs. a DD street car but stepping down to a smaller exhaust housing is never rocket science or brain surgery Click here to enlarge

We’re SUPER happy having completed this with boost control that is so spot on. 10psi (to overcome the wg spring before any duty cycle is needed on top of it to reach higher boost) is reached at 4200rpm in 4th gear on a non-load bearing Dynojet.

Car is a 2008 BMW 335i E90. More to follow, stay tuned! :)

PTF Sponsored Track Car – Custom BMW 135i N54

We recently received a call from an east coast shop owner who does some of the cleanest work I have ever seen. He runs a full race shop and has a 2008 135i with only 5000 miles on it. All 5000 miles are track miles as the car has never been registered as a car to run on the street. He is running RB turbos and full supporting bolt ons and tracks the car on 93 octane. We have decided to join him and support his tuning needs for the upcoming track seasons. After hitting the dyno today we have dialed the car in a bit more and focused on a tune for long / high heat and intense track sessions. 3+ hours on a road course tends to take its toll on a car and without the proper tuning and cooling it could cause problems. Between the tune we put together and the custom built parts on the car – this is going to be a very fun partnership.

Without the specific components, additional cooling modifications, and custom built race parts that he fabricated in his shop – this car would not run as well as it does. The car put out impressive numbers on the dyno today. It made about 443whp and 432wtq and never touched over 18.09 psi (set to hit and hold about 17.5psi but flirted with 18.09 for about 150rpms lol). We have a few more revisions to get everything dialed in perfectly. This was a third gear pull on the dyno as we ran out of time to start doing some 4th gear tuning. We will probably keep the car well under 18psi even at high load.

On to the impressive pictures!

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World Record: N54 DCT with Upgraded Clutch Packs from SSP Performance – 2012 BMW 335IS – 450WHP 490WTQ

Super excited about our recent tuning outcome with one of our local tuning customers. Joe’s 2012 BMW 335is with the DCT (Double Clutch) transmission is simply put, a stock turbo beast. The transmission is built with upgraded clutch packs from SSP Performance. We did our best to fully customize the Pro Tune on this N54 to take full advantage of the provided octane and methanol/water injection.

Here’s the review from the customer. Thanks Joe, enjoy the beast, see you at the track buddy ;)


Hey guys,

Just wanted to share my story about my DCT build and my WR Dyno. This is not intended to start a tuning war or to make anyone look stupid *cough*cough* 135 pages of garbage.

For starters I drive a 2012 335is with a DCT transmission, I began the build like every other enthusiast out there would, with a tune (JB4 to be exact). It later became FBO + meth + Protune with an upgraded clutch pack.

As I mentioned the car originally ran the JB4 G5 iso + BMS flash. I will never put down the BMS name as I believe that they deliver a sound product and top notch customer service, but it just wasn’t what I needed. The trans started encountering clutch slippage late last year while using any meth additive over 45 or being on map 7. The car gets beaten regularly and hits the strip at least once a month during the summer. It started off with some slippage during WOT shifts and later into not even being able to hold any power in the RPM range and sending the trans into a limp mode.

Since I’m located up in Canada and don’t drive much during the winter months, I called up Kris@ssp to discuss a possible clutch disc replacement. I was skeptical at first since theres a huge thread on how it doesn’t work, but I took the leap of faith anyways and pulled the trigger on the new SSP 16 plate clutch pack.Boy i’m I happy now for not listening to sticky. Kris hooked me up with a local DCT master technician who fly’s all over the world to upgrade GTR and Lambo clutches steve@SJL. In other words I was in great hands and I cannot thank Kris and Steve enough for the countless hours spent making my baby run how it should.

There was a short trial and error period but as of Saturday May 4th, my car was finally done. The technician advised me to go the flash route as the BMW TCU gets all its values directly from the ECU and tricking it with a piggy was affecting various systems/sensors (mostly load related) within the TCU. Earlier this month I got a hold of PTF, who are local to me and told them what I was trying to do. I then purchased the pro tune + the HFS4 and WOW what a difference it is to drive.

The car just goes, its hands down exactly what I wanted from this project when I started. PTF are amazing! I did both a road tune and a dyno tune and I can honestly say if your looking to bring your car to the next level I believe PTF is the way to go. It feels incredibly smooth and when needed it pulls like a freight train. The car currently runs 3 maps; one is a DD that is customized for 94+meth with conservative boost and timing. The next map is more aggressive running 94 + 100% meth and last but not least a map made strictly for race gas + meth.

Going back towards the DCT build, I would consider myself to be a complete noobie regarding the DCT trans. I know about line pressure and the discs itself but after that its like solving a rubix cube. So for more information on regarding the upgrade, I ask you to please email Kris@SSP.

I believe anyone trying to push big power with a DCT should give SSP a call and order these clutches. I’ve put on 1600 hard miles on them and not a single blip yet, the shifts are a tad firmer but still very comfortable for DD. I’m planning on getting a turbo upgrade by mid summer and well defiantly keep all of you posted. I intend to push the trans has hard as possible!!

The numbers below speak for themselves, consistent power pull after pull. We tried to hit 500tq but we didn’t want to put to much stress on the turbos. Since I cannot dig up my baseline, I wanted to let you guys know that a FBO g5iso + bms flash on 75 additive went on after me and put down 425/485 nemo .

I’ll be hitting the track later this month with PTF , watch out buraQ. Just waiting for my AD08s to come in, I truly believe this car can go deep into the 11s with its setup now.

Video’s…time slips and 60-120 runs will be posted later this month, just incase some of you don’t believe it works.

Do yourself a favour and contact PTF to get a fully customized map, I promise you wont regret it.

Much thanks PTF, SSP, SJL, columbusautomotive and all the boys part of JBC!!!

Mod List

AR Downpipes
Vibrant Resonators
NGK 9552