Boost oscillation and not reaching target. Wgdc.

elchicodeleste · 12-12-2022, 03:24 AM

Hi guys, the boost of my car is bouncing from 12 to 15 psi under WOT whereas target is 18.2psi. It never reaches this point. The logs shows that wastegates % oscillate too, both of them at the same very moment. I will add info about my car and also the logs (datazap link + image).
My assumptions is either solenoid in bad state/failing or turbos in bad condition, I have so much rattle, but a lot. I hope you can guide me. Thank you in advance.

My car:

135i n54 6MT with MHD Stage 2+ on 93
Dual Cone Intake
FMIC
Catless Downpipe
Chargepipe + BOV
Silicone Inlets 2"
LPFP Walbro 450

Also replaced almost everything can be maintained, brand new with less than 1000 kilometers like:

Every single gasket on the engine.
RB pcv
O2 sensors
LPFP sensor
Sparks
Coils
Turbo seals
Waterpump and thermostat
Alternator
Battery

All said, here I attach the link of the log.

https://datazap.me/u/elchicodeleste/...=1&data=4-5-23

Here you can see BOOST target and BOOST psi

Here you can see WGDC % and BOOST psi

iminhell1 · 12-14-2022, 12:19 PM

WGDC is clipping.
Either you're fighting a leak and the tune was done with the leak. Or the tune is just off. Should be able to make 18psi on mid 70% WGDC.

elchicodeleste · 12-14-2022, 03:54 PM

Quote:

Originally Posted by iminhell1

WGDC is clipping.
Either you're fighting a leak and the tune was done with the leak. Or the tune is just off. Should be able to make 18psi on mid 70% WGDC.

Thanks for the answer.

Yeah I see and feel the WGDC jumping. You can feel it under WOT.
The tune is via MHD.

So you think it is a leak and not bad solenoids?
And last question, WGDC means the vacuum applied to the actuators or the actual position of the physical actuator?

Cause if the second, I bet turbos/actuators/wastegates are blown.

About other leaks... I dont know. I replaced my vacuum lines, yesterday I tried removing CP with BOV and installing the OEM with diverter valves.. Only thing to be replaced to fight the "leak" are the IC o-rings. I will try the OEM too, just in case the IC itself has a pore.

iminhell1 · 12-15-2022, 02:46 AM

WGDC is how hard the solenoids are working. It can't tell if they are working equally though.
For instance, if one diaphragm is leaking it can't tell you that.

It sounds like the rear Wastegate Diaphragm is the one that tends to go bad first. It's a simple test, pull vacuum on it and see if it holds. If it can't, it's bad. Replace it.

12-12-2022, 03:24 AM	#1
elchicodeleste Registered 0 Rep 3 Posts Drives: 135i Join Date: Apr 2019 Location: Spain iTrader: (0)	Boost oscillation and not reaching target. Wgdc. Hi guys, the boost of my car is bouncing from 12 to 15 psi under WOT whereas target is 18.2psi. It never reaches this point. The logs shows that wastegates % oscillate too, both of them at the same very moment. I will add info about my car and also the logs (datazap link + image). My assumptions is either solenoid in bad state/failing or turbos in bad condition, I have so much rattle, but a lot. I hope you can guide me. Thank you in advance. My car: 135i n54 6MT with MHD Stage 2+ on 93 Dual Cone Intake FMIC Catless Downpipe Chargepipe + BOV Silicone Inlets 2" LPFP Walbro 450 Also replaced almost everything can be maintained, brand new with less than 1000 kilometers like: Every single gasket on the engine. RB pcv O2 sensors LPFP sensor Sparks Coils Turbo seals Waterpump and thermostat Alternator Battery All said, here I attach the link of the log. https://datazap.me/u/elchicodeleste/...=1&data=4-5-23 Here you can see BOOST target and BOOST psi Here you can see WGDC % and BOOST psi
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12-14-2022, 12:19 PM	#2
iminhell1 C2H5OH 3915 Rep 2,144 Posts Drives: 2010 SG 135i auto Join Date: May 2015 Location: Darwin, MN iTrader: (1)	WGDC is clipping. Either you're fighting a leak and the tune was done with the leak. Or the tune is just off. Should be able to make 18psi on mid 70% WGDC.
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12-15-2022, 02:46 AM	#4
iminhell1 C2H5OH 3915 Rep 2,144 Posts Drives: 2010 SG 135i auto Join Date: May 2015 Location: Darwin, MN iTrader: (1)	WGDC is how hard the solenoids are working. It can't tell if they are working equally though. For instance, if one diaphragm is leaking it can't tell you that. It sounds like the rear Wastegate Diaphragm is the one that tends to go bad first. It's a simple test, pull vacuum on it and see if it holds. If it can't, it's bad. Replace it.
	Appreciate 0 Quote