[ksalih]

Hey all. Just completed my first DE with the 335i, tons of fun. I began to limp towards the end... And after my last session I noticed my wastegates or gate wouldn't close (very audible exhaust note). At this same time I also noticed by boost solenoid or solenoids buzzing loudly. Are the two related? The limp modes were caused by underboosting due to wastegate stuck open.

[jimmer411]

Yes both are related. You could try bypassing the buzzing one but it is best to replace it and check for cracks in the vaccume lines.

[ksalih]

Originally Posted by jimmer411

Yes both are related. You could try bypassing the buzzing one but it is best to replace it and check for cracks in the vaccume lines.

From my understanding, both solenoids work in together, bypassing one would not allow them to work correctly? I'm sure both are due for replacement by now.

[C.Pop]

Are both buzzing or just one? If both, I'd be suspicious of something else... somewhat unlikely they'd both fail at the same time. That said, buzzing has been indicated in many cases of boost solenoid failure.

[boostaholic786]

You can bypass one of the boost solenoids and it should work fine but I personally would just get new ones depending on your miles. First, I would check all vacuum lines (especially the vacuum lines on the two canisters on the top and bottom) to see if it popped off. You can check vacuum by pulling off the top of the wastegate canister one by one and put your finger over the line and see if it holds your finger with pressure from vacuum. if one of them doesnt suck, you know you have a leak somewhere and just trace it down and find it. Shouldnt be hard. If that doesnt work, it might be mechanically stuck open from debris ect... try that and see what happens but most likely its a vacuum leak or boost solenoid.

[Scrippy]

Just replace both. They open and close together very rapidly. The oscillation between open and close is done to maintain precise vacuum for perfect boost control. Using just 1 would produce crappy results in boost and a lot of lag. The rail they booth are mounted on comes out with 4 bolts. This makes it easy to change them and all the tubing. They're like $130 each.

[ksalih]

Originally Posted by boostaholic786

You can bypass one of the boost solenoids and it should work fine but I personally would just get new ones depending on your miles. First, I would check all vacuum lines (especially the vacuum lines on the two canisters on the top and bottom) to see if it popped off. You can check vacuum by pulling off the top of the wastegate canister one by one and put your finger over the line and see if it holds your finger with pressure from vacuum. if one of them doesnt suck, you know you have a leak somewhere and just trace it down and find it. Shouldnt be hard. If that doesnt work, it might be mechanically stuck open from debris ect... try that and see what happens but most likely its a vacuum leak or boost solenoid.

I'll try this soon as I'm home to be sure it is indeed caused by a failing solenoid.

Originally Posted by C.Pop

Are both buzzing or just one? If both, I'd be suspicious of something else... somewhat unlikely they'd both fail at the same time. That said, buzzing has been indicated in many cases of boost solenoid failure.

They are too close together to tell the buzz noise apart. I think it's clear to conclude that at least one of the solenoids has failed. Whether that in fact is the reason one of my wastegates is stuck open, is unknown to me.

[C.Pop]

The solenoids control the wastegates. Put a long screwdriver on the wastegate and your ear up to the screwdriver handle, then repeat for other solenoid. Sort of like a stethoscope. It should be easy to tell which is the culprit. I ask because if they're both misbehaving your problem is more likely than not elsewhere.

[ksalih]

Replaced both solenoids, all visible vac lines and checked all connections from CP to throttle body. Took a log, pulled a p30FF. For some reason, my target boost is extremely low for a map 2 pull, should be targeting 14.5 psi. What the hell is going on? ..why is my target so low? I'll also mention my exhaust note is deep and loud, like a WG is stuck open. I've also tried map 0, same issue.

http://www.datazap.me/u/ksalih/map-2...g=0&data=1-3-4

[ksalih]

Removed JB4, issue still apparent.