[CoffeeBean]

This may be a dumb question but I can't find the answer anywhere. I just came from the N54 world which of course uses vacuum canisters etc for wastegate control. How does this different from the pneumatic/vacuum wastegate N55, or does it? I haven't seen a canister on the N55, and the N54 doesn't have control issues that some have with the PWG N55, so something has to be different. Anyone know? Thanks.

[enemigo13]

N55 vacuum canister is in the valve cover. canisters are not for boost control, they are just vacuum accumulators. What control issues does N55 have which does not have N54?

Originally Posted by CoffeeBean

This may be a dumb question but I can't find the answer anywhere. I just came from the N54 world which of course uses vacuum canisters etc for wastegate control. How does this different from the pneumatic/vacuum wastegate N55, or does it? I haven't seen a canister on the N55, and the N54 doesn't have control issues that some have with the PWG N55, so something has to be different. Anyone know? Thanks.

[CoffeeBean]

Originally Posted by enemigo13

N55 vacuum canister is in the valve cover. canisters are not for boost control, they are just vacuum accumulators. What control issues does N55 have which does not have N54?

Interesting, no wonder I couldn't find it. I understand they're not directly responsible for control but they are part of the system. Some people with tuned PWG N55s have issues with holding boost target and fluctuating boost. N54 has no such issues, so I was wondering what the difference is.

[enemigo13]

Originally Posted by CoffeeBean

Interesting, no wonder I couldn't find it. I understand they're not directly responsible for control but they are part of the system. Some people with tuned PWG N55s have issues with holding boost target and fluctuating boost. N54 has no such issues, so I was wondering what the difference is.

EWG is always better and faster control of the turbo than PWG. no matter pwg is n54, n55 or s63n

[zinner]

Electronic waste gate is just a motor opening and closing the waste gate. It's just faster and more adjustable than using vacuum based control strategies.

[CoffeeBean]

Right, I understand the EWG. I'm just trying to figure out why the PWG N55 has control issues but the N54 doesn't, if it's the same set up.

[bradsm87]

Originally Posted by CoffeeBean

Right, I understand the EWG. I'm just trying to figure out why the PWG N55 has control issues but the N54 doesn't, if it's the same set up.

Who said PWG N55 has control issues?

If you're talking about the inability to make much boost at high RPM, that's simply because the turbo is tiny. The EWG turbo has a bigger compressor wheel which helps it make a little more boost at high RPM.

[enemigo13]

Originally Posted by bradsm87

Who said PWG N55 has control issues?

If you're talking about the inability to make much boost at high RPM, that's simply because the turbo is tiny. The EWG turbo has a bigger compressor wheel which helps it make a little more boost at high RPM.

thats right, just its not “a little more” its about 300mbar or ~15% more. about overboosts - people forget one thing, ecu controls boost not with wg only but with throttle also. throttle is way faster method to kill unwanted boost than wg.one more thing - in ewg case you can see wgdc% up to 100% and up to 90% at high rpm. in pwg you will see max ~80% in spool up (while its 100.0% in pwg case) and ~70% max at high rpms. check mhd ewg/pwg stage2/2+ logs and you’ll see. not sure why is it so, believe ecu control strategy is different ewg vs pwg.

[cookiesowns]

Originally Posted by enemigo13

thats right, just its not “a little more” its about 300mbar or ~15% more. about overboosts - people forget one thing, ecu controls boost not with wg only but with throttle also. throttle is way faster method to kill unwanted boost than wg.one more thing - in ewg case you can see wgdc% up to 100% and up to 90% at high rpm. in pwg you will see max ~80% in spool up (while its 100.0% in pwg case) and ~70% max at high rpms. check mhd ewg/pwg stage2/2+ logs and you’ll see. not sure why is it so, believe ecu control strategy is different ewg vs pwg.

Yes. Because that's the true wgdc of the tiny PWG turbo. Because of backpressures the WG can open due to not enough vacuum or spring pressure at high airflow high boost scenarios.

The WG Pos table documents this quite accurately. I've experimented with tricking this table a teeny bit to try and have dme target more duty cycle on the pressure converter, and it worked.. kind of. Got more boost, but I didn't want to have trickery showing on logs so avoided doing this on stock turbo...

Stock turbo becomes a heat pump quite quick anyways so what's the point.

Originally Posted by CoffeeBean

Right, I understand the EWG. I'm just trying to figure out why the PWG N55 has control issues but the N54 doesn't, if it's the same set up.

Huh? Who has said there are control issues?? PWG control on the MEVD N55 is actually quite good if the tuner understands the tables properly. It took me a bit to accurately figure it out and build a proper model for various turbos. But once done I can target boost very accurately if enough time is spent.

Most N54 guys don't tune on PID purely but rather wg commanded... which is not bad as you still have some PD control. Unfortunately it's a short cut... and F series N55 don't have this luxury.

Originally Posted by CoffeeBean

Interesting, no wonder I couldn't find it. I understand they're not directly responsible for control but they are part of the system. Some people with tuned PWG N55s have issues with holding boost target and fluctuating boost. N54 has no such issues, so I was wondering what the difference is.

It's all in the tune. Just because you don't have a good tune for your car doesn't mean it's a mechanical issue. Yes PWG has some flaws compared to EWG..... but it doesn't mean the system is bad. It is also definitely to tune a PWG N55 without any of those issues.

[enemigo13]

Originally Posted by cookiesowns

Yes. Because that's the true wgdc of the tiny PWG turbo. Because of backpressures the WG can open due to not enough vacuum or spring pressure at high airflow high boost scenarios.

The WG Pos table documents this quite accurately. I've experimented with tricking this table a teeny bit to try and have dme target more duty cycle on the pressure converter, and it worked.. kind of. Got more boost, but I didn't want to have trickery showing on logs so avoided doing this on stock turbo...

Stock turbo becomes a heat pump quite quick anyways so what's the point.

the table you’re talking about is probably compressor power map (z values are in kw, one axis airflow kg/h, another compression ratio) and it’s used to generate final wgdc %. and yes this table is the same in e.g. n55 pwg 306hp and n55 ewg 306hp, I saw it different in F15 35i ewg only, if talking about 306hp versions. yes, you can tweak this table to get more wgdc or you can copy-paste it from x4 m40i or m2 (m2 has it even more aggressive). but it’s not the point. what i’m trying to say that even if this table is the same you can see 100.0% in ewg version on spool up, while you’ll never see it in pwg ecu version, max is 70-80%. the same story is at high rpms where ewg ecu can show up to 90% wgdc while pwg ecu even with m2 compressor power table used you will see max ~70% wgdc. and its not the matter of turbo size, pwg can be stage1 turbo (same compressor size as ewg) or ps2 (much bigger compressor/turbine).

[cookiesowns]

Originally Posted by enemigo13

the table you’re talking about is probably compressor power map (z values are in kw, one axis airflow kg/h, another compression ratio) and it’s used to generate final wgdc %. and yes this table is the same in e.g. n55 pwg 306hp and n55 ewg 306hp, I saw it different in F15 35i ewg only, if talking about 306hp versions. yes, you can tweak this table to get more wgdc or you can copy-paste it from x4 m40i or m2 (m2 has it even more aggressive). but it’s not the point. what i’m trying to say that even if this table is the same you can see 100.0% in ewg version on spool up, while you’ll never see it in pwg ecu version, max is 70-80%. the same story is at high rpms where ewg ecu can show up to 90% wgdc while pwg ecu even with m2 compressor power table used you will see max ~70% wgdc. and its not the matter of turbo size, pwg can be stage1 turbo (same compressor size as ewg) or ps2 (much bigger compressor/turbine).

WGPOS table is the WG position table, this is the lookup table for wastegate position ( simplifying it ). I'm not saying this is to solve spool, but the wgdc taper at max airflow of stock turbo. ( based on calibration )

no, not talking about compressor power map. There are many tables that allows you to control spool WGDC, even based on eco/dyn/sport maps I'm spooling at PS2 at 17psi by 3300rpm using about 83-85% WGDC.

There's about 2-5 tables that you need access to in order to do this. I unfortunately don't know the labels on N55 DAMOS.. since I mostly do custom tuning for friends on BM3.

[enemigo13]

Originally Posted by cookiesowns

WGPOS table is the WG position table, this is the lookup table for wastegate position ( simplifying it ). I'm not saying this is to solve spool, but the wgdc taper at max airflow of stock turbo. ( based on calibration )

no, not talking about compressor power map. There are many tables that allows you to control spool WGDC, even based on eco/dyn/sport maps I'm spooling at PS2 at 17psi by 3300rpm using about 83-85% WGDC.

There's about 2-5 tables that you need access to in order to do this. I unfortunately don't know the labels on N55 DAMOS.. since I mostly do custom tuning for friends on BM3.

my spoolup is usually 70-80% wgdc (while it’s always 100.0% in ewg case-still nobody answered why it’s not 100% in pwg cars) and I get ~70% wgdc until redline, WGPPOS table not touched. as I understand you have pwg ps2, what wgdc you have in the 5500-7000rpm interval?

[Chris S.]

Bringing this back from the dead. Anyone have an answer? I'm seeing 84% wgdc on spool up for a PS2 PWG N55. Long ago I figured out how to get 95%, but can't remember how. I'm hoping someone will share.

I expect there is a table not defined that provides a spool WGDC max value. I think I can trick it by adjusting the WG Pos - fur Vorsteuerung table to be 100% for everything over 80, but am worried that would cause unexpected issues somewhere else.

[harkes]

Originally Posted by Chris S.

Bringing this back from the dead. Anyone have an answer? I'm seeing 84% wgdc on spool up for a PS2 PWG N55. Long ago I figured out how to get 95%, but can't remember how. I'm hoping someone will share.

I expect there is a table not defined that provides a spool WGDC max value. I think I can trick it by adjusting the WG Pos - fur Vorsteuerung table to be 100% for everything over 80, but am worried that would cause unexpected issues somewhere else.

95% will not change anything when 80% is enough to keep the WG fully shut. PWG PS2 F-series here..

[Chris S.]

Originally Posted by harkes

95% will not change anything when 80% is enough to keep the WG fully shut. PWG PS2 F-series here..

Is 80% really holding wg closed? I've been doing some tweaks and it ramps down from 100% on tip in to around 87% before dropping hard to slow boost as it hits target. Trying a few more things to see if I can get it higher. I definitely hit 95% on the top end at 26 psi, but I think it's time for a heavier WG actuator. So now that I say that, maybe 80% is enough at low boost, when spoiling?

E-n55 PS2

[harkes]

Originally Posted by Chris S.

Is 80% really holding wg closed? I've been doing some tweaks and it ramps down from 100% on tip in to around 87% before dropping hard to slow boost as it hits target. Trying a few more things to see if I can get it higher. I definitely hit 95% on the top end at 26 psi, but I think it's time for a heavier WG actuator. So now that I say that, maybe 80% is enough at low boost, when spoiling?

E-n55 PS2

80% is just a number. Dont know how much is actually needed - might depend on load/gear/rpm. Just saying that 100% is not needed to keep WG fully closed during spool.

OTS PS2 is running ~70% during spool
https://datazap.me/u/harkes/ots-ps2-...0&data=3-17-23