[Nigelo]

Hey guys, had this posted on the n54 section but not but help coming from there so shooting up here.

About three weeks ago I noticed my 335i had lost its hard hit of low down urge. Im running Cobb stage2+fmic so was used to a pretty big punch from low down.

The car now feels super laggy in anything above 2nd gear (ie any gear when boost really helps). I threw an underboost code a week ago for the 2nd turbo so I got all the hoses, vacuum tanks and solenoids replaced. Turns out the 2nd tank had split and I had a blockage in the pipe leading from it also.

Now with all that done the car is still lagging something shocking. I logged boost there yesterday and the boost stayed at 6psi then suddenly jumped to 17.9psi at 5k rpm.

My wastegate now doesn't rattle at idle or off-throttle declaration. Do i still have vacuum problems? I was worried it was the 2nd turbo actuator was dead/stuck but since I can still hit nearly 18psi that's not likely?


Helps!!! :-S

[phil200tdi]

Sounds like a vacuum issue.

Could be the boost solenoids if you didn't replace these...

[LDNMaster]

If you can get hold of a Mitivac or similar I would start by measuring the vacuum supply at both pressure converters (solenoids) and if this is ok the next thing is to ensure the waste gates are moving properly. Best way is to go somewhere where they can plug in and activate them so you can observe them underneath and make sure there are no issues. Also be sure there are no boost leaks!

[Sparky68]

I have a spare solenoid if you need to borrow one to rule that out.

[Nigelo]

Hey guys, thanks for the info so far. Hopefully it's not the solenoids as I just replaced both of them, but a faulty new one is not outside the realms of possibility.

Does anyone know roughly what max psi I should be hitting? You're right about testing the wastegate action though. I'll search the forum for the pressure their meant to close at and get them checked.

[phil200tdi]

Dunno but Cobb is aggressive - maybe 16-17psi

[Nigelo]

Cheers Phil, so it seems I'm hitting the correct boost but it's just taking too long. Definitely sounds like a vacuum leak still somewhere. Going out tomorrow to do some data logging and see if I can throw a p30ff code again to prove I'm not imagining it all!

[Nigelo]

Managed to end up with basically no time to do any proper testing, but the car was getting up to 18.5psi boost, but its getting there so slowly and with so much lag. The disappearance of the wastegate rattle I had has me worried that the downpipe is somehow causing the actuator to engage too slowly by leaning against it (and thus preventing the rattle). Can't think of much else that could be happening but still allow me such a high boost level.

[phil200tdi]

Sticky Wastegate?

Worth testing the Vacuum system with a mitivac as mentionned earlier. This is a good DIY:

http://www.youtube.com/watch?feature...&v=80TYILifxy4

Not sure the readings will be the same with Cobb though as the JB4 controls the vacuum to the wastegates more directly.

Otherwise, its time to get the DP's off to take a look at the wastegates directly.

[Josh1a1h]

Once sorted, please post your findings

GD LUCK!!

[surrey 335i]

Originally Posted by Nigelo

Hey guys, had this posted on the n54 section but not but help coming from there so shooting up here.



The car now feels super laggy in anything above 2nd gear (ie any gear when boost really helps). I threw an underboost code a week ago for the 2nd turbo so I got all the hoses, vacuum tanks and solenoids replaced. Turns out the 2nd tank had split and I had a blockage in the pipe leading from it also.
:-S

Good luck getting it sorted.
Do you still have the old solenoids ?
(I could do with a spare if you want to sell them?)
thanks

[Narcosis]

Have you logged the car, and if so can you post the logs?

[Nigelo]

I'll get a proper saved log by the end of the week, I'm going to head to a local DIY garage that rents lift time to have an hour or so poke around the wastegates. I think they have a vacuum pump too so I can test the wastegates for stickiness or general uselessness!

Think the solenoids got chucked, but I'll post up later if I find them - they might be in the boot!

[Alpina_B3_Lux]

Could be the DVs too. Prone to rupturing over time at high boost.

[Nigelo]

Good idea with the DVs - anyone got some sitting around? :-D That or a updated charge pipe and fancy valves?

[Sparky68]

Originally Posted by surrey 335i

Good luck getting it sorted.
Do you still have the old solenoids ?
(I could do with a spare if you want to sell them?)
thanks

I have 2 spares, 1 of which I will sell if you want it. PM me if interested.

May have my DV's laying about, will check Nigelo

[surrey 335i]

Originally Posted by Nigelo

Think the solenoids got chucked, but I'll post up later if I find them - they might be in the boot!

thanks let me know if they turn up. cheers.

[Josh1a1h]

Is 1 hour long enough to even gain access to the Wastegates? wont removal of the Downpipes be necessary?

[Nigelo]

Found the one working solenoid in the boot, the other had a cracked nipple (ooer missus) so must've got binned.

With regards to the wastegates, I have a cunning plan, as Baldrick might say. Just going to use a borescope and poke it about in there, see what the banter is. Tomorrow I'm going to create some custom maps for the Cobb that will have different wastegate positions at idle, and watch on camera what the actuators do. Hopefully that's not as stupid as a Baldrick plan!

[bmwscrap]

I too am having the same problems as yourself. The problem has been diagnosed as the waste gates not sealing due to wear. No boost until 3500 and then all of a sudden get a boost spike and lots of throttle closure. the car is no fun to drive anymore. hope you get sorted

[Nigelo]

It's a blinking pain-in-the-rear. I haven't had a chance to do anything with it either after a dodgy takeaway has left me on the porcelain telephone for the last 3 days. :-(

[bmwscrap]

just realized ur from N.I. you dont happen to be form Newtownards? If so i'v seen the car a few times. looks well. I have a blue one with dark wheels.