Quick Cobb AP Boost Question

skinrock · 06-22-2012, 10:04 PM

I was about to do some runs at the drag strip, but noticed my AP reported 20.5 psi under Boost on the drive up (did some pulls). I'm wondering if this is a glitch or if it could be related to my Forge DV install. I used the yellow springs with two washers in each. I was told to use the stiffest setup possible since I was targeting 18.5.

Should I do a run and log it or reinstall them first?

Lulz_M3 · 06-22-2012, 10:12 PM

Post up a log.

skinrock · 06-22-2012, 10:21 PM

I'm pretty nervous about doing one run even.

Lulz_M3 · 06-22-2012, 10:34 PM

What rpm are you seeing the 20.5 psi at? Arent you Protuned? Can you pull up the map in ATR and view the load target table?

skinrock · 06-22-2012, 10:37 PM

I'm not sure of the rpm. I didn't log, just used the real time monitor and noticed the peak value while driving.

I think the protune is locked and therefore I can't read it.

rader1 · 06-22-2012, 10:41 PM

Honestly, need a log to say anything.

Lulz_M3 · 06-22-2012, 10:48 PM

eh, grab a buddy, your lap top, and your AP. Setup your dashboard and go for a spin, if you see something you don't like tell him to abort.

zeel · 06-22-2012, 11:07 PM

Could be a post shift boost spike?

new2the3 · 06-23-2012, 12:55 AM

Boost spike with the shift. When I record / live monitor my boost it shows the same thing around 20 psi, however without the spike I top out around 14... I wouldn't be worried about it

skinrock · 06-23-2012, 02:31 AM

Unfortunately, by the time I built the courage to do a run, they closed the ticket booth. I can't recall if I even shifted during some of the pulls where it hit 19-20. By the way, I have an auto if that matters.

I may just remove one set of washers and do some monitoring again. Even if these are spikes, that seems awfully high...but I understand it's meaningless without logs. I've just never seen it go that high so it scared me.

skinrock · 06-23-2012, 02:50 AM

Also I feel bad for not representing BMW while I was there. There was a perfect trifecta of muscle cars: a Camaro SS, Challenger 392 and Mustang 5.0. The Challenger was pretty slow, couldn't crack 13. The Camaro would have probably beaten me, I think it cut a 12.0 one time. My friend with an E92 went with JB4 + E85 and his best time was a 12.6 at 110 I think.

Lulz_M3 · 06-23-2012, 07:33 AM

Quote:

Originally Posted by skinrock

Unfortunately, by the time I built the courage to do a run, they closed the ticket booth. I can't recall if I even shifted during some of the pulls where it hit 19-20. By the way, I have an auto if that matters.

I may just remove one set of washers and do some monitoring again. Even if these are spikes, that seems awfully high...but I understand it's meaningless without logs. I've just never seen it go that high so it scared me.

The diverter valves aren't going to make you boost higher. The worst they could do is fail to open during a shift.

enrita · 06-23-2012, 08:27 AM

washers should not be used , just use the yellow springs. if they work for me they definetely would work for you.
probably a boost spike anyway. i see even 22 psi boost spike.

skinrock · 06-23-2012, 02:32 PM

Quote:

Originally Posted by Lulz_M3

The diverter valves aren't going to make you boost higher. The worst they could do is fail to open during a shift.

Quote:

Originally Posted by enrita

washers should not be used , just use the yellow springs. if they work for me they definetely would work for you.
probably a boost spike anyway. i see even 22 psi boost spike.

Thanks for the info. I'm going to remove the washers, hopefully this weekend.

E90SoFlo · 06-23-2012, 02:57 PM

Its just boost spikes, do a log.

Yodaime · 06-23-2012, 06:48 PM

spiking

benzy89 · 06-24-2012, 01:41 AM

+1 for Yellow Springs alone, that's what I'm using (stock turbos, Stage 2+FMIC Sport/Aggressive) and I'm holding boost fine, not dumping early, etc

boostaholic786 · 06-24-2012, 03:49 AM

I have stayed as well with the stock diverter valves just because they can actually handle alot of boost

max · 06-24-2012, 09:08 AM

Quote:

Originally Posted by benzy89

+1 for Yellow Springs alone, that's what I'm using (stock turbos, Stage 2+FMIC Sport/Aggressive) and I'm holding boost fine, not dumping early, etc

First I've heard about "Yellow Springs".
Is this an upgrade for our stock diverter valves? Where do you get them?
TIA

rader1 · 06-24-2012, 09:11 AM

Quote:

Originally Posted by max

First I've heard about "Yellow Springs".
Is this an upgrade for our stock diverter valves? Where do you get them?
TIA

No they're for the Forge DVs.

benzy89 · 06-24-2012, 11:29 AM

Quote:

Originally Posted by max

First I've heard about "Yellow Springs".
Is this an upgrade for our stock diverter valves? Where do you get them?
TIA

The Forge DVs (solid aluminum) are an upgrade over the OEM DVs (plastic) and have 4 different spring "options":

Green 5-15 PSI
Yellow 15-23 PSI
Blue 20-23 PSI
Red 30+ PSI

So most people running just a tune and intake would use the Green springs, anyone running an FBO car (stock turbos) would run the Yellow Springs, and anyone running aftermarket turbos might want to consider Blue if the DVs aren't holding pressure or are dumping early.

I was able to buy mine used, but you can but them off the Forge Motorsport website or from Jeff at Top Gear Solutions.

Joshboody · 06-24-2012, 12:17 PM

Stock DVs start relieving pressure at around 3-6psi differential pre/post throttle plate and when manifold is under vacuum. With afermarket dv/bov some of these mechanisms are altered or eliminated and could potentially add to drivability issues, especially when retaining DME boost control. I like the stock DVs personally.

06-22-2012, 10:04 PM	#1
skinrock Agent Smith 270 Rep 3,344 Posts Drives: 2016 i8 Join Date: Jan 2011 Location: The Matrix iTrader: (9) Garage List 2016 BMW i8 [10.00]	Quick Cobb AP Boost Question I was about to do some runs at the drag strip, but noticed my AP reported 20.5 psi under Boost on the drive up (did some pulls). I'm wondering if this is a glitch or if it could be related to my Forge DV install. I used the yellow springs with two washers in each. I was told to use the stiffest setup possible since I was targeting 18.5. Should I do a run and log it or reinstall them first? __________________ The i8 needs a V8 amirite?
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06-22-2012, 10:12 PM	#2
Lulz_M3 Banned 33 Rep 1,029 Posts Drives: AW 335i 6MT Join Date: Oct 2011 Location: Jax, Fl iTrader: (0)	Post up a log.
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06-22-2012, 10:21 PM	#3
skinrock Agent Smith 270 Rep 3,344 Posts Drives: 2016 i8 Join Date: Jan 2011 Location: The Matrix iTrader: (9) Garage List 2016 BMW i8 [10.00]	I'm pretty nervous about doing one run even. __________________ The i8 needs a V8 amirite?
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06-22-2012, 10:34 PM	#4
Lulz_M3 Banned 33 Rep 1,029 Posts Drives: AW 335i 6MT Join Date: Oct 2011 Location: Jax, Fl iTrader: (0)	What rpm are you seeing the 20.5 psi at? Arent you Protuned? Can you pull up the map in ATR and view the load target table?
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06-22-2012, 10:37 PM	#5
skinrock Agent Smith 270 Rep 3,344 Posts Drives: 2016 i8 Join Date: Jan 2011 Location: The Matrix iTrader: (9) Garage List 2016 BMW i8 [10.00]	I'm not sure of the rpm. I didn't log, just used the real time monitor and noticed the peak value while driving. I think the protune is locked and therefore I can't read it. __________________ The i8 needs a V8 amirite?
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06-22-2012, 10:41 PM	#6
rader1 Banned 70 Rep 2,197 Posts Drives: Cobb Stage 2+ 135i Join Date: Apr 2011 Location: Roanoke, VA iTrader: (0)	Honestly, need a log to say anything.
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06-22-2012, 10:48 PM	#7
Lulz_M3 Banned 33 Rep 1,029 Posts Drives: AW 335i 6MT Join Date: Oct 2011 Location: Jax, Fl iTrader: (0)	eh, grab a buddy, your lap top, and your AP. Setup your dashboard and go for a spin, if you see something you don't like tell him to abort.
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06-22-2012, 11:07 PM	#8
zeel Lieutenant 14 Rep 579 Posts Drives: 08 AW e92 335i Join Date: Nov 2010 Location: MD/NOVA/DC iTrader: (2) Garage List 2008 bmw e92 335i [7.34]	Could be a post shift boost spike?
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06-23-2012, 12:55 AM	#9
new2the3 Colonel 380 Rep 2,067 Posts Drives: 2020 X3M Competition Join Date: Jun 2006 Location: San Diego iTrader: (0)	Boost spike with the shift. When I record / live monitor my boost it shows the same thing around 20 psi, however without the spike I top out around 14... I wouldn't be worried about it __________________ 2020 X3MC 2009 135i: AW/CR Aluminum Trim, 6 speed, M-Sport, Premium, Heated Seats, Ipod, BMW Performance Pedals, BMW Performance SSK, BMW Performance Exhaust, BMW Performance Grills E93 M3 FSB
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06-23-2012, 02:31 AM	#10
skinrock Agent Smith 270 Rep 3,344 Posts Drives: 2016 i8 Join Date: Jan 2011 Location: The Matrix iTrader: (9) Garage List 2016 BMW i8 [10.00]	Unfortunately, by the time I built the courage to do a run, they closed the ticket booth. I can't recall if I even shifted during some of the pulls where it hit 19-20. By the way, I have an auto if that matters. I may just remove one set of washers and do some monitoring again. Even if these are spikes, that seems awfully high...but I understand it's meaningless without logs. I've just never seen it go that high so it scared me. __________________ The i8 needs a V8 amirite?
	Appreciate 0 Quote

06-23-2012, 02:50 AM	#11
skinrock Agent Smith 270 Rep 3,344 Posts Drives: 2016 i8 Join Date: Jan 2011 Location: The Matrix iTrader: (9) Garage List 2016 BMW i8 [10.00]	Also I feel bad for not representing BMW while I was there. There was a perfect trifecta of muscle cars: a Camaro SS, Challenger 392 and Mustang 5.0. The Challenger was pretty slow, couldn't crack 13. The Camaro would have probably beaten me, I think it cut a 12.0 one time. My friend with an E92 went with JB4 + E85 and his best time was a 12.6 at 110 I think. __________________ The i8 needs a V8 amirite?
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06-23-2012, 08:27 AM	#13
enrita Major General 161 Rep 7,377 Posts Drives: 335i - Big turbos Join Date: Sep 2008 Location: Italian in Sweden iTrader: (0)	washers should not be used , just use the yellow springs. if they work for me they definetely would work for you. probably a boost spike anyway. i see even 22 psi boost spike. __________________ 07 335i AT - MOTIV 750 - MHD E85 BMS flash - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Snow Stg. 3 - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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06-23-2012, 02:57 PM	#15
E90SoFlo Banned 196 Rep 2,669 Posts Drives: E90 335i Join Date: Jun 2011 Location: Naples, FL iTrader: (9)	Its just boost spikes, do a log.
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06-24-2012, 01:41 AM	#17
benzy89 Banned 79 Rep 2,396 Posts Drives: '08 E90 335i Join Date: Jan 2012 Location: Northern NJ iTrader: (3) Garage List 2008 BMW 335i [7.50]	+1 for Yellow Springs alone, that's what I'm using (stock turbos, Stage 2+FMIC Sport/Aggressive) and I'm holding boost fine, not dumping early, etc
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06-24-2012, 03:49 AM	#18
boostaholic786 Captain 40 Rep 623 Posts Drives: E92 N54 with MHD Custom flash Join Date: Dec 2011 Location: Plano TX iTrader: (0)	I have stayed as well with the stock diverter valves just because they can actually handle alot of boost __________________ [SIZE="2"]Crimson Red E92 335i M-sport 6-speed with MHD custom stage 2+ flash only , 40% E85/93 mix,+ HRE P40S wheels, KW Clubsport, M3 sways,+BMW performance CF Mirrors, BMW Performance CF deck lid spoiler,+ CF interior trim, p3 vent boost gauge,+ LUX angel eyes (11.73@124mph on street tires)
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06-24-2012, 12:17 PM	#22
Joshboody Lieutenant Colonel 65 Rep 1,708 Posts Drives: pickemuptruck Join Date: Jul 2009 Location: Phoenix, AZ iTrader: (7)	Stock DVs start relieving pressure at around 3-6psi differential pre/post throttle plate and when manifold is under vacuum. With afermarket dv/bov some of these mechanisms are altered or eliminated and could potentially add to drivability issues, especially when retaining DME boost control. I like the stock DVs personally.
	Appreciate 0 Quote