[jakeadake]

I've been chasing this 30ff underboost code since I've taken ownership of an '07 335xi at bone stock form. Car drives fine until you start building boost and hit 4000 rpm's, then you get the *ding* engine malfunction reduced power warming that corresponds to a 30ff turbo pressure too low code. I have added a MHD stage 1 + fmic tune with CP, DV's, FMIC, and DCI's and still get the dreaded 30ff. I had my Indy do a smoke test and he claimed that he adjusted both WG actuators, but to no avail. Car has WG chatter at cold startup for about 30 seconds, then goes away. It pulls like a freight train until I hit 4,000 rpm, then goes into limp mode. Any ideas? I'm at my wits end here...

What I've done:
All new silicon vacuum lines (WG actuators-boost solenoids-canisters-oil filter housing...)
Both WG actuators tested to fully close at 5.9hg and hold vacuum
Tested vacuum canisters and replaced one with split nipple
Replaced stock CP with a BMS charge pipe and Forge DV valves (yellow springs)
New Pierburg boost solenoids
Helix FMIC
BMS DCI
Boost leak tested and heard air at lower FMIC connection, fixed the clamp, still 30ff....

[jin]

Check inlets?

[jakeadake]

Originally Posted by jin

Check inlets?

Thanks for the tip, I actually haven't checked the inlets. When I did the boost leak test at 12psi I could hear air escaping from the rear (inlet?). Without a lift is there any trick to checking both inlets?

[jin]

The rear one can come loose. Easy way is to try lever it back on from the top of engine with something.

The rear cone moving around is what causes the rear inlet to come loose so recommend you tether it to the manifold.

[TrAcK TRaP]

Most of the times Helix FMIC (driver side) connection comes loose ask me how I know

[jakeadake]

Thanks guys, I just removed all of the undertrays and still could not figure out how to access the rear turbo inlet to check if it was seated...but checked my hot and cold side intercooler connections and found no indications of leaking. I pressurized the inlets and confirmed no leaks at the intercooler. However, I found a substantial leak at the oil filler cap?! Any harm in pressurizing my crankcase (12-15psi) like this? I didn't feel like taking the cowl off to block the PCV heater hose. Could this be my 30ff boost leak lol?

[mojobmw_e90]

Look where the downpipes are, right above the downpipes you should be able to see the rear turbo. If not than u might have to remove the downpipe to properly access the connection. There is a gasket that sits on the turbo inlet and the plastic tube covers it. Over time this slides off.

[jakeadake]

Ok, I followed your instructions and located the rear inlet. It is completely on the turbo, which I verified by leveraging a long screwdriver on it hoping to slide it on further. I then removed the PCV hose that attached to the rear inlet and capped it off and tried another boost leak test. Nothing audible...? I also used my Mityvac again to test all of the vacuum lines running to the canisters across the manifold and they hold vacuum fine. Tested both wastegate actuators and found the rear rod is fully closed by 200 bar of vacuum and the front actuator is fully closed by 225-250 bar. Both actuators move freely without binding and hold vacuum. Can't be the solenoids because they were just replaced. Man, I'm stumped at this point! Sooo close to just dropping the subframe and pulling the turbos...

[feuer]

Any other codes? I have seen 30ff coming during limp mode cause by other issues, like vanos, fuel or ignition.

[jakeadake]

Originally Posted by feuer

Any other codes? I have seen 30ff coming during limp mode cause by other issues, like vanos, fuel or ignition.

Hmmm well running ECU codes from my MHD flasher module on an android tablet is only returning the 30ff "turbocharger pressure too low". I've put only around 300 miles on the car since I've owned it over the past 4 months, but originally when it was completely stock I scanned it after the first limp mode using a BavarianTechnic cable and it returned the 30ff, P0171 and P0174 (bank 1 and bank 2 lean), and a code for leaving the car running when I filled up with gas.. As of now, I'm only getting the 30ff turbo pressure code when I clear codes and trigger the limp mode going into boost.

I just rebuilt a set of cores with the TurboLab guy's rebuild kit and wastegate flapper fix and I'm so close to just biting the bullet to install these. I'd hate to go to that much effort only to find out it was something simple haha...

[feuer]

Originally Posted by jakeadake

Hmmm well running ECU codes from my MHD flasher module on an android tablet is only returning the 30ff "turbocharger pressure too low". I've put only around 300 miles on the car since I've owned it over the past 4 months, but originally when it was completely stock I scanned it after the first limp mode using a BavarianTechnic cable and it returned the 30ff, P0171 and P0174 (bank 1 and bank 2 lean), and a code for leaving the car running when I filled up with gas.. As of now, I'm only getting the 30ff turbo pressure code when I clear codes and trigger the limp mode going into boost.

I just rebuilt a set of cores with the TurboLab guy's rebuild kit and wastegate flapper fix and I'm so close to just biting the bullet to install these. I'd hate to go to that much effort only to find out it was something simple haha...

Like I said 30ff can accompany other code that are the actual reason for the limp mode.
I have seen in with codes for misfires, codes for fuel pressure and vanos solenoids and when those issues were resolved the 30ff didn't reappeared.
I'm not sure how if works but is somehow link with engine going into limp mode.
I would say address P0171 and P0174 first especially if the info on when they occur, like time and rpms is identical or before the 30ff
Also, if you can post a log.

[jin]

Originally Posted by jakeadake

Thanks guys, I just removed all of the undertrays and still could not figure out how to access the rear turbo inlet to check if it was seated...but checked my hot and cold side intercooler connections and found no indications of leaking. I pressurized the inlets and confirmed no leaks at the intercooler. However, I found a substantial leak at the oil filler cap?! Any harm in pressurizing my crankcase (12-15psi) like this? I didn't feel like taking the cowl off to block the PCV heater hose. Could this be my 30ff boost leak lol?

How do you know there is a vacuum leak at the oil cap? Might be a bad pcv valve

[jakeadake]

Originally Posted by jin

How do you know there is a vacuum leak at the oil cap? Might be a bad pcv valve

I heard air escaping from the oil cap when I pressurized the inlets without blocking off the PCV. I have a RB PCV in there right now so that should be solid. From what I understand I was unintentionally pressuring the crankcase during my boost leak test making the cap leak?

Also to clarify the previous post, the P0171 and P0174 seemed to go away after I cleaned the TMAP sensor. It was a bit dirty. After resetting ECU/adaptations I'm continuously only throwing the 30ff code. Will see if I can get a log through the MHD when I'm back in town with the car.

[DennisPacMo]

Very similar circumstances to my 335xi. I smoke tested it and found no leaks whatsoever. I decided to manually adjust my rear turbo wastegate closed a little more and voila, problem fixed. The actuator is worn and old and after tightening the clevis on the rear turbo, problem gone. Couldn't get the front one adjusted, even when removing downpipes so I said F it. Either way, problem gone.

[jakeadake]

Originally Posted by DennisPacMo

Very similar circumstances to my 335xi. I smoke tested it and found no leaks whatsoever. I decided to manually adjust my rear turbo wastegate closed a little more and voila, problem fixed. The actuator is worn and old and after tightening the clevis on the rear turbo, problem gone. Couldn't get the front one adjusted, even when removing downpipes so I said F it. Either way, problem gone.

That's refreshing to hear, I may give the rear actuator rod another tweak. At this point I think it warrants pulling the DP's to feel the adjustment and wear. When you dropped your XI down pipes did you have to completely drop the subframe, steering rack, or passenger CV axle?

I asked my Indy what the trick was to adjust the front actuator and he said "a pick and a magnet". Doesn't sound right to me since it takes a stubby 10mm for the locknut and a tiny 4mm to turn the rod...I'm actually doubting he smoked it and adjusted the rear at this point, so I'm going to go through those again...

[musa]

Hey Jakeadake, any update? Did you resolve your issue?

[feuer]

Originally Posted by jakeadake

I asked my Indy what the trick was to adjust the front actuator and he said "a pick and a magnet". Doesn't sound right to me since it takes a stubby 10mm for the locknut and a tiny 4mm to turn the rod...I'm actually doubting he smoked it and adjusted the rear at this point, so I'm going to go through those again...

Sorry, that's why he is a mechanic and you are not. He will loosen up the two bolts holding the actuator onto the turbo. With a pick he will space out the actuator from the turbo housing. With a magnet he will insert washers and refasten the bolts. The easier way is to cut the two washers, like a horse shoe.

I'm affiliated with a shop in Smithsville, NC. LEt me know. I can refer you there.

[DennisPacMo]

Originally Posted by jakeadake

That's refreshing to hear, I may give the rear actuator rod another tweak. At this point I think it warrants pulling the DP's to feel the adjustment and wear. When you dropped your XI down pipes did you have to completely drop the subframe, steering rack, or passenger CV axle?

I asked my Indy what the trick was to adjust the front actuator and he said "a pick and a magnet". Doesn't sound right to me since it takes a stubby 10mm for the locknut and a tiny 4mm to turn the rod...I'm actually doubting he smoked it and adjusted the rear at this point, so I'm going to go through those again...

Hang the subframe from the steering shaft and leave the tie rods connected.

the front turbo needs a pick for sure. I pulled the clevis and spun it til it stopped. worked fine. the front I couldn't do but if I did, the pick method is the trick.

[jakeadake]

Originally Posted by feuer

Sorry, that's why he is a mechanic and you are not. He will loosen up the two bolts holding the actuator onto the turbo. With a pick he will space out the actuator from the turbo housing. With a magnet he will insert washers and refasten the bolts. The easier way is to cut the two washers, like a horse shoe.

I'm affiliated with a shop in Smithsville, NC. LEt me know. I can refer you there.

Feuer- I appreciate that. I very well may take you up on the referral if this last effort stumps me. Smithville, as in Brunswick Co. on the coast? I'm in the Piedmont about 4 hrs from there. Hoping you meant Smithfield

Thanks for the insight, that's a creative approach. When I asked about removing the thermostat, waterpump, fan, intercooler to get to the front he claimed they did none of that so that seemed like a hell of a feat. Right now I'm away from the car until the weekend, but I have it on jackstands ready to start pulling the stock DP's. As an incentive I bought some VRSF catless DP's to take their place as well as new actuators.

My plan of action for the weekend is to install new actuators and readjust/ check the play on the WG arms. If nothing is binding I'm hoping this will cure my 30ff. If they're shot, well I'll bow to the turbo gods and pray upon my rebuilt cores...but that'll take me a couple weekends. I'll keep the thread updated as I make progress! This is my first BMW, direct injection/twin turbo inline 6 for that matter. I traded a built Cummins turbo diesel for the car, so some familiarity with a turbo 6 cyl. platform.

[feuer]

Originally Posted by jakeadake

Feuer- I appreciate that. I very well may take you up on the referral if this last effort stumps me. Smithville, as in Brunswick Co. on the coast? I'm in the Piedmont about 4 hrs from there. Hoping you meant Smithfield

Thanks for the insight, that's a creative approach. When I asked about removing the thermostat, waterpump, fan, intercooler to get to the front he claimed they did none of that so that seemed like a hell of a feat. Right now I'm away from the car until the weekend, but I have it on jackstands ready to start pulling the stock DP's. As an incentive I bought some VRSF catless DP's to take their place as well as new actuators.

My plan of action for the weekend is to install new actuators and readjust/ check the play on the WG arms. If nothing is binding I'm hoping this will cure my 30ff. If they're shot, well in with a the rebuilt cores...but that'll take me a couple weekends. I'll keep the thread updated as I make progress!

I have been dealing with n54 for 3-4y now and yet to see failed actuator/s. so will advise you against it.
Why don't you try another tune? Might be your tune.
H
ere is the shop info:
Import Car Service 36 E Edgerton St, Unit C, Smithfield, NC 27577 (919) 205-1133

I was there two weeks ago. Probably Justin will answer but ask for Alec, the owner.

[TrAcK TRaP]

Originally Posted by feuer

Any other codes? I have seen 30ff coming during limp mode cause by other issues, like vanos, fuel or ignition.

What you are saying is even injectors spark plugs or coils can throw 30FF boost leak code instead of misfire?

[TrollToll]

Tl;dr

But every 30FF has a solution. If you've replaced and verified the vacuum side and you've verified no boost leaks are present then you're down to either bad wastegate solenoids, worn actuators, or failing turbos. My money would be on worn wastegates.

Sometimes the wastegates wear so that they will be okay most of the time, but tend to bind when closing and fail to fully seat. There is a video on YouTube demonstrating this.