[ExpensiveTaste]

Just yesterday, my 335xi was running beautifully on JB4 Map 5. It had power, spooled up quickly, and was a fun car to drive. My boost gauge tied into the DV vacuum hose was showing 13.5psi peak and I had no issues other than wastegate rattle on start up and changing from on throttle to off throttle as well as the opposite.

This morning I drove the car and it was building boost VERY slowly. I thought, maybe it just hasn't warmed up yet. Once it got past the 160 mark on the oil temp gauge, I gave it some WOT and it took about 5 seconds to get to 3psi and stayed there.

Background: JB4 Map 5 usually running 13.5psi, CX Racing Intercooler installed about a month ago, BMS DCI which might be a little dirty, and a wastegate rattle that still rattles after adjusting but is better. No Check Engine Light is Visible.

Where should I look first? At no point did I hear a hose pop off. How can I make sure that my wastegates are fully sealing?

[Jeff@TopGearSolutions]

Log WGDC

[themyst]

Originally Posted by Jeff@topgearsolutions

Log WGDC

On the JB4 it's PWM

[mycoupe]

Check the intercooler to charge pipe connection and the charge pipe to throttle body connection. Those seem to be the biggest culprits.

[C4sF80M3]

Originally Posted by ExpensiveTaste

Just yesterday, my 335xi was running beautifully on JB4 Map 5. It had power, spooled up quickly, and was a fun car to drive. My boost gauge tied into the DV vacuum hose was showing 13.5psi peak and I had no issues other than wastegate rattle on start up and changing from on throttle to off throttle as well as the opposite.

This morning I drove the car and it was building boost VERY slowly. I thought, maybe it just hasn't warmed up yet. Once it got past the 160 mark on the oil temp gauge, I gave it some WOT and it took about 5 seconds to get to 3psi and stayed there.

Background: JB4 Map 5 usually running 13.5psi, CX Racing Intercooler installed about a month ago, BMS DCI which might be a little dirty, and a wastegate rattle that still rattles after adjusting but is better. No Check Engine Light is Visible.

Where should I look first? At no point did I hear a hose pop off. How can I make sure that my wastegates are fully sealing?

Sounds like the wastegate is sticking. Try putting some Anti-seize compound on the rear wastegate arm. That helped me tremendously, especially on track.

[mattsfeir]

Check vacuum lines also.

[s2k_335i]

My was leaked at the intercooler and the cp. Like other suggested check all your lines

[Jeff@TopGearSolutions]

Originally Posted by themyst

On the JB4 it's PWM

Oh right I forgot.

[ExpensiveTaste]

Alright so I checked the following places:

-Metal Y-pipe to intercooler piping
-Intercooler inlet/outlet
-Both sides of the charge pipe
-Throttle body

All were tight and wouldn't spin. After tightening all of these another notch, I took the car out for a quick test drive and same problem. However, I did get 2 codes saying something like boost pressure is under target and something about the fuel injector ignition something or other.

I'm baffled how I could have such a drastic change in boost so quickly.

I did check the wastegate arm and it moves in and out freely. I know the wastegate is working because when I give it gas, the rattle goes away. What's the next step?

[themyst]

Assuming everything else is fine, I'd investigate the wastegate solenoids.

[ExpensiveTaste]

Originally Posted by themyst

Assuming everything else is fine, I'd investigate the wastegate solenoids.

Both at the same time? I would assume the boost drop wouldn't be that much if one failed and only one turbo was working?

[Jeff@TopGearSolutions]

How about resetting adaptations. Was that done yet?

[themyst]

Originally Posted by ExpensiveTaste

Both at the same time? I would assume the boost drop wouldn't be that much if one failed and only one turbo was working?

If you're leaking at the solenoids, your car would build boost very slowly, and eventually when they fail, you can't build boost at all.

[themyst]

Originally Posted by Jeff@topgearsolutions

How about resetting adaptations. Was that done yet?

The JB4 can handle resetting of o2 and octane adaptations, but nothing else really.

[ExpensiveTaste]

Does anyone have a vacuum diagram for the car to make sure the solenoid vacuum lines aren't kinked or something?

[Jeff@TopGearSolutions]

Originally Posted by themyst

The JB4 can handle resetting of o2 and octane adaptations, but nothing else really.

I guess my work here is done....

[themyst]

they are on the left hand side of the motor with the cover off when facing the engine bay.

They cost about $100 a pop to replace. I think cn555ic has one for sale

[Joshboody]

check the vacuum lines... i don't OP understands this. Follow wastegate to solenoid, to vacuum canisters (big oval thingys on the passenger side front), to the top of the engine under the engine cover to the main vacuum line from the pump around the oil filter housing.

[EastBayE90]

If its not the solenoid vacuum lines it is these lines. My car ran tits and just one day it would not make over 3 psi. We found both of these vacuum lines to be leaking and after replacing them the car was fine. Check these lines I have included a link to the post explaining what lines to check. Hope your find the leak!

http://www.e90post.com/forums/showthread.php?t=546560

[ExpensiveTaste]

So I messed with a bunch of stuff including taking off both DV's and putting them back on. I told my wife to start the car and I watched the back Wastegate arm move back and forth in a very notchy way when she revved the motor. I greased it up with some hi-temp grease and the car is back to normal!!!! I'm going to try and replace most of the vacuum lines anyway as a precautionary step.

Thanks Everyone!!!

[JamesM3M5]

Same problem on a customer 135i today! 30FF - Boost pressure too low. I'll have to call him to have him come by for a quick lube job. I mean, wait, that didn't come out right...

His rear WG actuator will NOT close the WG. Tried manually putting vacuum on it, it just moves slightly and hangs. I even manually pushed it with a prybar, gently of course. Still sticky as hell. Hopefully we can save him some grief since he just bought this thing and has only put 500 miles on it.

[JamesM3M5]

Update: FAIL.

The actuator is fine, moves normally. The pivot that the rod clips to is fine - a little loose even. The wastegate pivot shaft that enters the turbo housing binds up. I tried some lube, but there is too much axial and radial play. Something in there is worn out, and the poor dude needs a new turbo.

Does Rob Beck fix this problem? I thought I read something about that...