JB4 flucuation

BoosTonian · 03-19-2015, 09:10 AM

Hello everyone,

So I recently installed a JB4 G5 in my car with the BMS pump flash, running map 5. Lagfix set at 60.

I know the autotune needs a couple pulls to tune itself, so I did them. One thing I noticed though is it seems like the car cant find a constant boost pressure to hold until 4000+ rpm. Especially on the highway.

When I gWOT it, the boost fluctuates from 17 down to 14 up to 16 down and so on. Then it holds a constant boost right around 15 when it's at 4000+ rpm. Living in New England I knew oil temp and outside temp plays into it, so I got the car nice and warm (around 200+F). Outside air temp was 24.

Not sure if others have seen this and if its normal. Sparks just changed (I know I will probably get that question)

torrque · 03-19-2015, 09:15 AM

I have noticed the same thing on mine , but had no hesitations at the time or driveability issues, so I ignored it. How are you measuring boost, just by the gas indicator hack in jb4 ?

I don't think that is very accurate ...

BoosTonian · 03-19-2015, 09:22 AM

Quote:

Originally Posted by torrque

I have noticed the same thing on mine , but had no hesitations at the time or driveability issues, so I ignored it. How are you measuring boost, just by the gas indicator hack in jb4 ?

I don't think that is very accurate ...

ya, im going by whats on the gas gauge. But I can feel it when I'm WOTing it. I can feel the boost fluctuating and going up/down.

torrque · 03-19-2015, 09:36 AM

I would log boost data in that case provided you have the usb cable, and reach out to the guys at JB4 ?

cotmfk · 03-19-2015, 09:42 AM

Definitely log.

Dumb question - traction control was off? Traction control cutting the power could cause this. Especially since you said it was only 24.. traction would be a huge issue.

BoosTonian · 03-19-2015, 09:49 AM

Quote:

Originally Posted by cotmfk

Definitely log.

Dumb question - traction control was off? Traction control cutting the power could cause this. Especially since you said it was only 24.. traction would be a huge issue.

i have been running with dsc off fully, i know it can cause issues with both cutting power and the tune picking it up as knock.

zack335i · 03-19-2015, 10:03 AM

24 is still cold as shit! cement could be slighty frozen in the grooves, tires arent as warm. deff Log

Jeff@TopGearSolutions · 03-19-2015, 11:39 AM

Without a log I'd start looking at your FMIC and Charge Pipe connections and making sure they are squared up and maybe tighten them a bit more. It's possible that you are leaking boost but it's not enough to trigger the light. The under-boost code takes 3-4 seconds of sustained under-boost.

mike@x-ph.com · 03-19-2015, 02:41 PM

+1 for logs

BoosTonian · 03-19-2015, 03:09 PM

Quote:

Originally Posted by mike@x-ph.com

+1 for logs

Alright, seems like the consensus is to run logs (which is what I was going to do). Im gonna run them tonight and post them

BoosTonian · 03-19-2015, 10:42 PM

here are two logs i did with map 2 selected. i also did a log of map 5 (after i did a few pulls). I did a pull on map 5 and a spirited driving log as well. logs are in this order
1. Map 2 pull 2
2. Map 2 pull 1
3. Map 5 pull 1
4. Map 5 spirited driving

335NJ · 03-19-2015, 11:36 PM

You should upload the logs to Datazap.me for easier reading.

BoosTonian · 03-20-2015, 12:30 PM

Quote:

Originally Posted by Jeff@TopGearSolutions

Without a log I'd start looking at your FMIC and Charge Pipe connections and making sure they are squared up and maybe tighten them a bit more. It's possible that you are leaking boost but it's not enough to trigger the light. The under-boost code takes 3-4 seconds of sustained under-boost.

http://www.datazap.me/u/three35drive...log=2&data=1-4

http://www.datazap.me/u/three35drive...log=1&data=1-4

http://www.datazap.me/u/three35drive...log=0&data=1-4

BoosTonian · 03-20-2015, 12:32 PM

Quote:

Originally Posted by 335NJ

You should upload the logs to Datazap.me for easier reading.

maps are up on datazap.com, see above post for them

03-19-2015, 09:10 AM	#1
BoosTonian Lieutenant Colonel 778 Rep 1,498 Posts Drives: 2017 MB C63 S AMG Coupe Join Date: Oct 2013 Location: Boston, MA iTrader: (2) Garage List 2017 INFINITI Q60 S ... [10.00]	JB4 flucuation Hello everyone, So I recently installed a JB4 G5 in my car with the BMS pump flash, running map 5. Lagfix set at 60. I know the autotune needs a couple pulls to tune itself, so I did them. One thing I noticed though is it seems like the car cant find a constant boost pressure to hold until 4000+ rpm. Especially on the highway. When I gWOT it, the boost fluctuates from 17 down to 14 up to 16 down and so on. Then it holds a constant boost right around 15 when it's at 4000+ rpm. Living in New England I knew oil temp and outside temp plays into it, so I got the car nice and warm (around 200+F). Outside air temp was 24. Not sure if others have seen this and if its normal. Sparks just changed (I know I will probably get that question) __________________ 2017 MB C63 S Coupe - DINAN \| MODAL WORKS retired: GranTurismo MC, Giulia Quadrifoglio, B8.5 RS5, Q60 RedSport, e82 135, F80, e92 M3, e90 M3, (2) e92 335, B8 S4, C209 CLK55 AMG, e46 330 Last edited by BoosTonian; 03-19-2015 at 09:22 AM..
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03-19-2015, 09:15 AM	#2
torrque Banned 304 Rep 650 Posts Drives: Ferrari F430, E92 M3, 335xi Join Date: Apr 2014 Location: Newton, MA iTrader: (0) Garage List 2005 Ferrari F430 [9.08] 2009 BMW M3 [10.00] 2008 BMW 335xi [0.00]	I have noticed the same thing on mine , but had no hesitations at the time or driveability issues, so I ignored it. How are you measuring boost, just by the gas indicator hack in jb4 ? I don't think that is very accurate ...
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03-19-2015, 09:36 AM	#4
torrque Banned 304 Rep 650 Posts Drives: Ferrari F430, E92 M3, 335xi Join Date: Apr 2014 Location: Newton, MA iTrader: (0) Garage List 2005 Ferrari F430 [9.08] 2009 BMW M3 [10.00] 2008 BMW 335xi [0.00]	I would log boost data in that case provided you have the usb cable, and reach out to the guys at JB4 ?
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03-19-2015, 09:42 AM	#5
cotmfk Major General 2151 Rep 6,177 Posts Drives: M3 Join Date: Mar 2009 Location: Somewhere between DC and FL iTrader: (12)	Definitely log. Dumb question - traction control was off? Traction control cutting the power could cause this. Especially since you said it was only 24.. traction would be a huge issue. __________________ When you say impact instead of affect/effect, you are communicating that you don't understand the difference between the two words, and are too lazy to learn.
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03-19-2015, 10:03 AM	#7
zack335i Private First Class 15 Rep 137 Posts Drives: 2010 e90 335i w Sports package Join Date: Feb 2015 Location: United States , NJ iTrader: (1)	24 is still cold as shit! cement could be slighty frozen in the grooves, tires arent as warm. deff Log
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03-19-2015, 11:39 AM	#8
Jeff@TopGearSolutions 3474 Rep 79,211 Posts Drives: C6 Z06, 09 335i, 10 335xi Join Date: Dec 2008 Location: www.TopGearSolutions.com iTrader: (37)	Without a log I'd start looking at your FMIC and Charge Pipe connections and making sure they are squared up and maybe tighten them a bit more. It's possible that you are leaking boost but it's not enough to trigger the light. The under-boost code takes 3-4 seconds of sustained under-boost.
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03-19-2015, 02:41 PM	#9
mike@x-ph.com BimmerPost Supporting Vendor 27337 Rep 196,669 Posts Drives: 07-335/12-328/18-M4/21-M4CP Join Date: Sep 2013 Location: Las Vegas iTrader: (23)	+1 for logs __________________ Check out our current sale by clicking on this link! https://x-ph.com/sale/ Phone number 702-494-9435
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03-19-2015, 10:42 PM	#11
BoosTonian Lieutenant Colonel 778 Rep 1,498 Posts Drives: 2017 MB C63 S AMG Coupe Join Date: Oct 2013 Location: Boston, MA iTrader: (2) Garage List 2017 INFINITI Q60 S ... [10.00]	here are two logs i did with map 2 selected. i also did a log of map 5 (after i did a few pulls). I did a pull on map 5 and a spirited driving log as well. logs are in this order 1. Map 2 pull 2 2. Map 2 pull 1 3. Map 5 pull 1 4. Map 5 spirited driving Attached Images __________________ 2017 MB C63 S Coupe - DINAN \| MODAL WORKS retired: GranTurismo MC, Giulia Quadrifoglio, B8.5 RS5, Q60 RedSport, e82 135, F80, e92 M3, e90 M3, (2) e92 335, B8 S4, C209 CLK55 AMG, e46 330
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03-19-2015, 11:36 PM	#12
335NJ Colonel 535 Rep 2,872 Posts Drives: 2008 335i 6MT E90 Join Date: Feb 2014 Location: NJ/Philadelphia Suburbs iTrader: (1)	You should upload the logs to Datazap.me for easier reading.
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