F30POST
F30POST
2012-2015 BMW 3-Series and 4-Series Forum
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
BMW 3-Series and 4-Series Forum (F30 / F32) | F30POST > Technical Forums > N55 Turbo Engine / Drivetrain / Exhaust Modifications > Boost Taper
proTUNING Freaks
Post Reply
 
Thread Tools Search this Thread
      02-13-2020, 10:47 PM   #1
Davidschu
Enlisted Member
United_States
3
Rep
43
Posts

Drives: Bmw 335i x-drive
Join Date: Aug 2019
Location: RI

iTrader: (0)

Hi all. I'm having some issues with my boost tapering off really bad after about 4400 rpm. This is an issue I first noticed a while ago when I flashed bm3 stage 1. Car felt like it had tons more power vs the stock tune down low but not much up top. Getting on the highway the car feels so much stronger pulling from low rpm in 4th gear vs starting mid rpm in 3rd.

I looked at my logs then and noticed my boost was tapering off really bad. Thought I might have a leak. Upgraded my intercooler, double checked that the ic/cp connection was good. Still had the same taper issue.

I know that pwg cars do have an issue with not holding boost well in high rpm. However the tune made by bm3 is specifically for pwg cars and targets around 16 psi in the upper rpms so I assume a stock pwg car should be capable of hitting that. However, my actual boost psi is tapering down to around 10 psi by the time I hit 6k

So I thought maybe a catless downpipe would help my turbo flow better. So I went that route and flashed stage 2 91 yet I am still seeing the same issue in my logs.

As I mentioned before getting on the highway in 3rd feels weak compared to 4th. I looked at my logs and the boost target in 3rd drops down to around 10 psi, yet in 4th and 2nd it's around 15-16psi. Not sure why this is happening.

I think it's possible I have a leak however it's weird that the car can hold 15psi up until 4k rpm which makes me think there's not a leak. However, I have ordered new bigger o-rings for the ic/cp connection and also plan on creating a boost leak tester based on one of the threads I read on here. I would also like to note that I have a stock diverted valve and have 65k miles.

So does anyone have any insight on why my 3rd gear boost targets are so low? And does anyone with a pwg car with stock turbo have logs to compare to? Thanks in advance

Here are my logs: First two are 4th gear pulls, last two are 1-4 pulls

http://www.bootmod3.net/log?id=5e43449ec090c6419c25d19c

http://www.bootmod3.net/log?id=5e43440dc090c6419c25d19a

http://www.bootmod3.net/log?id=5e43441ad10b432feef138ec

http://www.bootmod3.net/log?id=5e43440ed10b432feef138ea
Appreciate 1
oma3710110.00

      02-13-2020, 11:13 PM   #2
Phantom10R
First Lieutenant
144
Rep
386
Posts

Drives: 2015 335i, 2015 X3 x35i
Join Date: Aug 2018
Location: Chelsea, MI

iTrader: (0)

Do you have the trans flash?
Appreciate 0
      02-14-2020, 01:23 AM   #3
harkes
Lieutenant Colonel
harkes's Avatar
China
728
Rep
1,734
Posts

Drives: M135i, NSX and AE86
Join Date: Apr 2014
Location: Xiamen, China

iTrader: (0)

Problem is bad tuning. F-series is notoriously difficult to tune. I own a 2012 PWG myself and I have been trying to get it running perfectly with Pure Stage 2 for +3 years (first JB4, then ESS flash, then JB4 with BM3 backend flash, then BM3 flash alone, now MHD). I am now on revision 47 (!!!) with Twisted Tuning and the car does the same as yours. Inconsistent boost in the different gears.
I have now found hope in Pureboost (Fabian Baum) which seems to know what he is doing. He is also the man behind the PWG PS2 OTS map for MHD.

First picture is Twisted Rev 47
Second picture is Pureboost Rev 1
Attached Images
  
__________________
M135i PWG, MHD, Pure Stage2, Torqbyte CM5-LT, xHP
(A Dane in China)
Appreciate 0
      02-14-2020, 01:33 AM   #4
Techno 9000
First Lieutenant
129
Rep
307
Posts

Drives: 435D Estoril Blue
Join Date: Jan 2018
Location: East Sussex

iTrader: (0)

”So does anyone have any insight on why my 3rd gear boost targets are so low? ...... Thanks in advance”

From what I have read, 3rd gear is torque limited by the transmission, is it not?

Anyone else agree?
Appreciate 0
      02-14-2020, 01:42 AM   #5
harkes
Lieutenant Colonel
harkes's Avatar
China
728
Rep
1,734
Posts

Drives: M135i, NSX and AE86
Join Date: Apr 2014
Location: Xiamen, China

iTrader: (0)

Quote:
Originally Posted by Techno 9000 View Post
”So does anyone have any insight on why my 3rd gear boost targets are so low? ...... Thanks in advance”

From what I have read, 3rd gear is torque limited by the transmission, is it not?

Anyone else agree?
10-11psi will not get you anywhere near the torque limiter
__________________
M135i PWG, MHD, Pure Stage2, Torqbyte CM5-LT, xHP
(A Dane in China)
Appreciate 0
      02-14-2020, 07:27 AM   #6
Davidschu
Enlisted Member
United_States
3
Rep
43
Posts

Drives: Bmw 335i x-drive
Join Date: Aug 2019
Location: RI

iTrader: (0)

No trans flash. The previous owner did have the m-performance power kit installed but I don't think that does anything to the trans. And to clarify my car is an 8 speed a/t.
Harkes looking at your log in both pictures it looks like your targets are 18-20 in 3rd gear. Sure your not reaching them in the first picture but that's target. My target in 3rd is only 10-11. If it's caused by bad tuning is everyone that's running ots bm3 maps seeing this ?
Appreciate 0
      02-14-2020, 08:39 AM   #7
oma3710
Major
oma3710's Avatar
110
Rep
1,036
Posts

Drives: 435i vert
Join Date: Apr 2012
Location: Simpsonville, SC

iTrader: (1)

I am having same issue with my custom tune on ewg. Target is 22psi and after 5k rpm I am hitting around 17psi.
__________________
__________________
Jordan E30 Tune~ BM3 trans tune~ XDI-35~ 3.5 T-map sensor~ VRSF HD FMIC~ VRSF Chargepipe~ VRSF Catless Downpipe~ CTS Intake~ FTP boost pipe~ FTP intake inlet~ Turbosmart dual bov~
Appreciate 0
      02-14-2020, 08:45 AM   #8
oma3710
Major
oma3710's Avatar
110
Rep
1,036
Posts

Drives: 435i vert
Join Date: Apr 2012
Location: Simpsonville, SC

iTrader: (1)

Quote:
Originally Posted by Phantom10R View Post
Do you have the trans flash?
Does the trans flash cause this?
__________________
__________________
Jordan E30 Tune~ BM3 trans tune~ XDI-35~ 3.5 T-map sensor~ VRSF HD FMIC~ VRSF Chargepipe~ VRSF Catless Downpipe~ CTS Intake~ FTP boost pipe~ FTP intake inlet~ Turbosmart dual bov~
Appreciate 0
      02-14-2020, 09:17 AM   #9
harkes
Lieutenant Colonel
harkes's Avatar
China
728
Rep
1,734
Posts

Drives: M135i, NSX and AE86
Join Date: Apr 2014
Location: Xiamen, China

iTrader: (0)

Quote:
Originally Posted by oma3710 View Post
I am having same issue with my custom tune on ewg. Target is 22psi and after 5k rpm I am hitting around 17psi.
17psi is the physical limit of the stock turbo. Nothing can be done to make it hit 20psi.
__________________
M135i PWG, MHD, Pure Stage2, Torqbyte CM5-LT, xHP
(A Dane in China)
Appreciate 0
      02-14-2020, 09:19 AM   #10
oma3710
Major
oma3710's Avatar
110
Rep
1,036
Posts

Drives: 435i vert
Join Date: Apr 2012
Location: Simpsonville, SC

iTrader: (1)

Quote:
Originally Posted by harkes View Post
17psi is the physical limit of the stock turbo. Nothing can be done to make it hit 20psi.
I know other people on this forum with same mods hitting 20psi all day with the same tuner.
__________________
__________________
Jordan E30 Tune~ BM3 trans tune~ XDI-35~ 3.5 T-map sensor~ VRSF HD FMIC~ VRSF Chargepipe~ VRSF Catless Downpipe~ CTS Intake~ FTP boost pipe~ FTP intake inlet~ Turbosmart dual bov~
Appreciate 0
      02-14-2020, 09:21 AM   #11
harkes
Lieutenant Colonel
harkes's Avatar
China
728
Rep
1,734
Posts

Drives: M135i, NSX and AE86
Join Date: Apr 2014
Location: Xiamen, China

iTrader: (0)

Quote:
Originally Posted by Davidschu View Post
No trans flash. The previous owner did have the m-performance power kit installed but I don't think that does anything to the trans. And to clarify my car is an 8 speed a/t.
Harkes looking at your log in both pictures it looks like your targets are 18-20 in 3rd gear. Sure your not reaching them in the first picture but that's target. My target in 3rd is only 10-11. If it's caused by bad tuning is everyone that's running ots bm3 maps seeing this ?
Ok, let's not say bad because it works. Let's call it sloppy. You will not see that in the factory map.
__________________
M135i PWG, MHD, Pure Stage2, Torqbyte CM5-LT, xHP
(A Dane in China)
Appreciate 0
      02-14-2020, 09:49 AM   #12
akgambino
Lieutenant
Canada
148
Rep
416
Posts

Drives: 2013 F30 335xi M-Sport (PWG)
Join Date: Mar 2017
Location: Saskatchewan

iTrader: (0)

Quote:
Originally Posted by harkes View Post
Problem is bad tuning. F-series is notoriously difficult to tune. I own a 2012 PWG myself and I have been trying to get it running perfectly with Pure Stage 2 for +3 years (first JB4, then ESS flash, then JB4 with BM3 backend flash, then BM3 flash alone, now MHD). I am now on revision 47 (!!!) with Twisted Tuning and the car does the same as yours. Inconsistent boost in the different gears.
I have now found hope in Pureboost (Fabian Baum) which seems to know what he is doing. He is also the man behind the PWG PS2 OTS map for MHD.

First picture is Twisted Rev 47
Second picture is Pureboost Rev 1
Ps2. Seems irrelevant to this discussion.
__________________
2013 F30 335i xDrive M-Sport 6MT (FBO/BM3 custom tune by HCP, 91 oct)
Appreciate 0
      02-14-2020, 09:58 AM   #13
akgambino
Lieutenant
Canada
148
Rep
416
Posts

Drives: 2013 F30 335xi M-Sport (PWG)
Join Date: Mar 2017
Location: Saskatchewan

iTrader: (0)

Quote:
Originally Posted by Davidschu View Post
Hi all. I'm having some issues with my boost tapering off really bad after about 4400 rpm. This is an issue I first noticed a while ago when I flashed bm3 stage 1. Car felt like it had tons more power vs the stock tune down low but not much up top. Getting on the highway the car feels so much stronger pulling from low rpm in 4th gear vs starting mid rpm in 3rd.

I looked at my logs then and noticed my boost was tapering off really bad. Thought I might have a leak. Upgraded my intercooler, double checked that the ic/cp connection was good. Still had the same taper issue.

I know that pwg cars do have an issue with not holding boost well in high rpm. However the tune made by bm3 is specifically for pwg cars and targets around 16 psi in the upper rpms so I assume a stock pwg car should be capable of hitting that. However, my actual boost psi is tapering down to around 10 psi by the time I hit 6k

So I thought maybe a catless downpipe would help my turbo flow better. So I went that route and flashed stage 2 91 yet I am still seeing the same issue in my logs.

As I mentioned before getting on the highway in 3rd feels weak compared to 4th. I looked at my logs and the boost target in 3rd drops down to around 10 psi, yet in 4th and 2nd it's around 15-16psi. Not sure why this is happening.

I think it's possible I have a leak however it's weird that the car can hold 15psi up until 4k rpm which makes me think there's not a leak. However, I have ordered new bigger o-rings for the ic/cp connection and also plan on creating a boost leak tester based on one of the threads I read on here. I would also like to note that I have a stock diverted valve and have 65k miles.

So does anyone have any insight on why my 3rd gear boost targets are so low? And does anyone with a pwg car with stock turbo have logs to compare to? Thanks in advance

Here are my logs: First two are 4th gear pulls, last two are 1-4 pulls

http://www.bootmod3.net/log?id=5e43449ec090c6419c25d19c

http://www.bootmod3.net/log?id=5e43440dc090c6419c25d19a

http://www.bootmod3.net/log?id=5e43441ad10b432feef138ec

http://www.bootmod3.net/log?id=5e43440ed10b432feef138ea
There is nothing wrong with your car or the tune. Anyone who says the stock pwg turbo can hold more boost between 5000rpm and redline is full of shit. Even if wgdc was maxed out it would make little to no difference and be running that tiny turbo so far out of its efficiency range that it wouldn't make any more power either.

It's just the curse of the pwg, ewg cars hold around 3psi of boost to redline more due to a larger diameter turbo impeller and more refined wg control that is handled by the dme instead of vacuum.

All you can do to fix this is upgrade to a PS1 turbo which will put the boost in line with what a stock ewg car would be and maybe a bit more or ultimately go PS2 or comparable stage 2 turbo.

The 3rd gear issue is torque limiter same thing in 6th on 8at cars. Get a trans flash from xhp to resolve.

You could try going the custom tune route but don't go into expecting more boost in the upper rev range, more focus on fueling and timing which when done properly and specific to your car, octane and ambient conditions will net better times/power/feel than a couple more psi of boost ever would.
__________________
2013 F30 335i xDrive M-Sport 6MT (FBO/BM3 custom tune by HCP, 91 oct)
Appreciate 1
      02-14-2020, 10:04 AM   #14
btetier
Enlisted Member
United_States
26
Rep
48
Posts

Drives: 2015 BMW 335i M-Sport
Join Date: Apr 2019
Location: Philadelphia, PA

iTrader: (0)

Quote:
Originally Posted by oma3710 View Post
I am having same issue with my custom tune on ewg. Target is 22psi and after 5k rpm I am hitting around 17psi.
Dude you are really pushing your stock turbo to the limit if you are targeting 22lbs of boost. The stock EWG turbo's efficiency range ends around 5400-5600rpms, so that is why your boost tapers off after that. Also, why not just upgrade your turbot to a ps2 and run a more moderate tune, get higher numbers, and it will be much safer on your car. Pushing 22lbs on a stock turbo is going to cause it to go bad so much faster.
Appreciate 0
      02-14-2020, 02:13 PM   #15
Davidschu
Enlisted Member
United_States
3
Rep
43
Posts

Drives: Bmw 335i x-drive
Join Date: Aug 2019
Location: RI

iTrader: (0)

Based on my first 4th gear logs I'm hitting 13.3psi while targeting 16.1psi at 5000rpm

In the 2nd 4th gear log I'm hitting 12.9psi while targeting 15.5 psi at 5000 rpm.


And at 6k rpm I'm getting 11 psi with 16.3 target in run 1.

In run two I'm getting 11 psi with 16.2 psi target at 6k.


And if you look at the logs the taper continues downward as the rpms raise.

Is this really all I can expect from the stock pwg turbo with a fbo setup? Why would ptf have the targets set that high for pwg cars if the boost falls off that early at only 5k rpm?

And that is great news to hear that the trans flash will fix my low boost targets in 3rd. I will definitely be purchasing shortly
Appreciate 1
oma3710110.00

      02-14-2020, 04:16 PM   #16
akgambino
Lieutenant
Canada
148
Rep
416
Posts

Drives: 2013 F30 335xi M-Sport (PWG)
Join Date: Mar 2017
Location: Saskatchewan

iTrader: (0)

Quote:
Originally Posted by Davidschu View Post
Based on my first 4th gear logs I'm hitting 13.3psi while targeting 16.1psi at 5000rpm

In the 2nd 4th gear log I'm hitting 12.9psi while targeting 15.5 psi at 5000 rpm.


And at 6k rpm I'm getting 11 psi with 16.3 target in run 1.

In run two I'm getting 11 psi with 16.2 psi target at 6k.


And if you look at the logs the taper continues downward as the rpms raise.

Is this really all I can expect from the stock pwg turbo with a fbo setup? Why would ptf have the targets set that high for pwg cars if the boost falls off that early at only 5k rpm?

And that is great news to hear that the trans flash will fix my low boost targets in 3rd. I will definitely be purchasing shortly
Yes, this is all completely normal for stock pwg turbo.
__________________
2013 F30 335i xDrive M-Sport 6MT (FBO/BM3 custom tune by HCP, 91 oct)
Appreciate 0
      02-14-2020, 04:38 PM   #17
harkes
Lieutenant Colonel
harkes's Avatar
China
728
Rep
1,734
Posts

Drives: M135i, NSX and AE86
Join Date: Apr 2014
Location: Xiamen, China

iTrader: (0)

Quote:
Originally Posted by oma3710 View Post
Quote:
Originally Posted by harkes View Post
17psi is the physical limit of the stock turbo. Nothing can be done to make it hit 20psi.
I know other people on this forum with same mods hitting 20psi all day with the same tuner.
At what rpm? Stock turbo can do 20 at 3000 but not at 6000
__________________
M135i PWG, MHD, Pure Stage2, Torqbyte CM5-LT, xHP
(A Dane in China)
Appreciate 0
      02-14-2020, 07:29 PM   #18
Davidschu
Enlisted Member
United_States
3
Rep
43
Posts

Drives: Bmw 335i x-drive
Join Date: Aug 2019
Location: RI

iTrader: (0)

That's disappointing to here, guess I'll have to start watching some ps1 installation videos. Was really hoping I'd be able to hit the boost targets in the current ots tunes. Anyways I still plan to do a boost test shortly to see if I can squeeze out a little more psi.

Just to verify the xhp trans flash will raise my 3rd gear boost targets to be similar to the other gears? Thanks
Appreciate 0
      02-16-2020, 09:15 PM   #19
harkes
Lieutenant Colonel
harkes's Avatar
China
728
Rep
1,734
Posts

Drives: M135i, NSX and AE86
Join Date: Apr 2014
Location: Xiamen, China

iTrader: (0)

Quote:
Originally Posted by Davidschu View Post
That's disappointing to here, guess I'll have to start watching some ps1 installation videos. Was really hoping I'd be able to hit the boost targets in the current ots tunes. Anyways I still plan to do a boost test shortly to see if I can squeeze out a little more psi.

Just to verify the xhp trans flash will raise my 3rd gear boost targets to be similar to the other gears? Thanks
No. xHP is only influencing how your transmission operate not the engine. Unless...you are exceeding the transmission torque limits, in which case the TCU will ask the DME to limit power, but that is not what is happening in your case. With xHP installed torque limits in all gears is 885ftlb.
__________________
M135i PWG, MHD, Pure Stage2, Torqbyte CM5-LT, xHP
(A Dane in China)
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 02:31 AM.




f30post
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2020, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST