It's that whoa WTF kinda boost...

Dark_Knight_335 · 12-19-2015, 03:22 PM

Had a WTF moment today- somehow my PIII gauge read some shitted up negative numbers for a short time for boost.

As it happens, turning the car off and on seems to have fixed that - although it is still -1.1 or so as it always is for some reason....and yes, my charge pipe is fine, and I was barely moving when it happened...

Ideas? Only thing I remember is coming around and breaking my rear end loose a bit because of some asshole holiday shopper that was in a daze, blocking my ability to safely get into the intersection.

timothy2001 · 12-19-2015, 07:55 PM

Having my own WTF moment right now.......what is that gauge?

snaimpally · 12-19-2015, 09:47 PM

I think it was reading the state of the flux capacitor ...

theweebabySeamus · 12-19-2015, 10:49 PM

Quote:

Originally Posted by timothy2001

Having my own WTF moment right now.......what is that gauge?

P3

Dark_Knight_335 · 12-19-2015, 11:11 PM

I thought for sure my charge pipe bit it. Time to call the kind folks at P3!

timothy2001 · 12-20-2015, 06:36 AM

Quote:

Originally Posted by Dark_Knight_335

I thought for sure my charge pipe bit it. Time to call the kind folks at P3!

At least your top is not leaking.

Welcome to NBA Jam · 12-20-2015, 07:24 AM

Your turbo is spinning backwards, making negative boost. Be careful, the resulting vortex could cause your car to suck itself into a singularity, trapping you in a dimension where only reruns of the Seinfeld Soup Nazi episode are on every channel, and green is actually blue.

jwzimm · 12-20-2015, 02:38 PM

Lol! It is funny how new tech can make folks forget the old. Before the days of valvetronic the manifold pressure would be negative during low throttle and idle situations. The N55 still has a throttle plate but when things are working normally it is wide open allowing the valvetronic system to handle the load metering. It looks like you might be having either throttle closures due to over boost or something is amiss with your valvetronic system

CantCatchMe · 12-20-2015, 09:48 PM

Quote:

Originally Posted by timothy2001

At least your top is not leaking.

Haha exactly what I thought, could be worse

Sidewinderpb · 12-21-2015, 09:28 AM

Quote:

Originally Posted by Welcome to NBA Jam

Your turbo is spinning backwards, making negative boost. Be careful, the resulting vortex could cause your car to suck itself into a singularity, trapping you in a dimension where only reruns of the Seinfeld Soup Nazi episode are on every channel, and green is actually blue.

Rotary Rasp · 12-21-2015, 09:37 AM

Isn't normal to have vacuum when you're off the throttle?

Dark_Knight_335 · 12-21-2015, 10:56 AM

Quote:

Originally Posted by Rotary Rasp

Isn't normal to have vacuum when you're off the throttle?

Nope, not that I know of...hence my concern. It's going to the dealer next Monday, who also just so happens to be a DINAN and a P3 dealer

grizz311 · 12-21-2015, 02:54 PM

I thought it was normal. My boosted 350z gauge always read negative psi when off throttle for the vacuum. I don't remember the numbers though.

mike@x-ph.com · 12-21-2015, 03:18 PM

Quote:

Originally Posted by Rotary Rasp

Isn't normal to have vacuum when you're off the throttle?

Yes it it is normal to have negative boost when you're off the throttle

weehe126 · 12-21-2015, 04:06 PM

No it is not normal. Boost is taken from the TMAP sensor in the charge pipe. The cp never sees vac.

trixdout · 12-22-2015, 08:56 PM

Quote:

Originally Posted by weehe126

No it is not normal. Boost is taken from the TMAP sensor in the charge pipe. The cp never sees vac.

IF the engine is generating vacuum, how does the cp not see this as well?

weehe126 · 12-22-2015, 09:54 PM

The N55 does not generate vacuum in the charge pipes. Look up a technical article on it. If it did have vacuum it would only be in the intake manifold, after the throttle body. Just think about it, where would a normal vac source be for a boost gauge? On the intake mani, not the charge pipe. The P3 gauge gets the info from the TMAP sensor on the CP from the CAN connection. Can you find a pneumatic boost guage for the N55 to source pressure from the intake mani?

JETmn · 12-23-2015, 09:46 AM

Quote:

Originally Posted by weehe126

The N55 does not generate vacuum in the charge pipes. Look up a technical article on it. If it did have vacuum it would only be in the intake manifold, after the throttle body. Just think about it, where would a normal vac source be for a boost gauge? On the intake mani, not the charge pipe. The P3 gauge gets the info from the TMAP sensor on the CP from the CAN connection. Can you find a pneumatic boost guage for the N55 to source pressure from the intake mani?

If you have any references to this, I would love to see it. I was not able to find anything and I know it does not work this way on other platforms, but they don't have valvetronic. I don't understand how the ending could be creating boost at idle. The engine should be in vacuum at that point or any time you have turbo lag.

You say the intake manifold can be at vacuum, but the CP can't? How can that be when they are connected? I thought the point of valvetronic was to not use a throttle body under normal operation to create a choke point?

trixdout · 12-23-2015, 01:57 PM

Quote:

Originally Posted by JETmn

If you have any references to this, I would love to see it. I was not able to find anything and I know it does not work this way on other platforms, but they don't have valvetronic. I don't understand how the ending could be creating boost at idle. The engine should be in vacuum at that point or any time you have turbo lag.

You say the intake manifold can be at vacuum, but the CP can't? How can that be when they are connected? I thought the point of valvetronic was to not use a throttle body under normal operation to create a choke point?

This. Unless the diverter valve is the source of air to the intake manifold, I cannot see that the chargepipe would be completely blocked off from the intake manifold during deceleration.

I ordered an electric boost gauge. Got the passenger-side vent sitting at home (for a dirt cheap price, thanks ecs) and waiting on that boost gauge. I will plumb it to the meth bung on the cp and log it myself.

Dark_Knight_335 · 12-24-2015, 10:20 PM

Quote:

Originally Posted by mike@x-ph.com

Quote:

Originally Posted by Rotary Rasp

Isn't normal to have vacuum when you're off the throttle?

Yes it it is normal to have negative boost when you're off the throttle

Yes, -1.0 or so, not -19 Mike

Gotta be something wrong in boost land...going to the dealer Monday, we'll see.

JETmn · 12-28-2015, 09:20 AM

Quote:

Originally Posted by Dark_Knight_335

Yes, -1.0 or so, not -19 Mike

Gotta be something wrong in boost land...going to the dealer Monday, we'll see.

Vacuum is not normally measured in PSI. It may be switching to inches of mercury.

Dark_Knight_335 · 12-28-2015, 01:15 PM

Quote:

Originally Posted by JETmn

Quote:

Originally Posted by Dark_Knight_335

Yes, -1.0 or so, not -19 Mike

Gotta be something wrong in boost land...going to the dealer Monday, we'll see.

Vacuum is not normally measured in PSI. It may be switching to inches of mercury.

You mean it's not Plutonium Seconds per Inch?

Oh wait, this is a real thing!

https://en.m.wikipedia.org/wiki/Inch_of_mercury

12-19-2015, 03:22 PM	#1
Dark_Knight_335 Came to the N55 Darkside 1112 Rep 12,740 Posts Drives: 2011 335 E93 M-Sport Join Date: May 2010 Location: NY/NJ iTrader: (28)	It's that whoa WTF kinda boost... Had a WTF moment today- somehow my PIII gauge read some shitted up negative numbers for a short time for boost. As it happens, turning the car off and on seems to have fixed that - although it is still -1.1 or so as it always is for some reason....and yes, my charge pipe is fine, and I was barely moving when it happened... Ideas? Only thing I remember is coming around and breaking my rear end loose a bit because of some asshole holiday shopper that was in a daze, blocking my ability to safely get into the intersection. Attached Images
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12-19-2015, 07:55 PM	#2
timothy2001 Major 850 Rep 1,181 Posts Drives: 2011 E92 M3 6MT ZCP Join Date: Oct 2014 Location: NE Florida iTrader: (0) Garage List 2011 M3 E92 [0.00]	Having my own WTF moment right now.......what is that gauge?
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12-19-2015, 09:47 PM	#3
snaimpally Major 136 Rep 1,192 Posts Drives: 2011 335i MT Join Date: Mar 2014 Location: Austin, TX iTrader: (9) Garage List 2011 BMW 335i [0.00]	I think it was reading the state of the flux capacitor ... __________________ PTF Map, Pure Turbo Stage 1, GFB DV+, Mfactory LSD, AA FMIC, B12 Pro Kit, M3 FCA, AR DP and Dynavin N6, Mosconi AS100.4, AS100.4, AS200.2, Micro Precision tweeters & woofers, Esotar2 1200
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12-19-2015, 11:11 PM	#5
Dark_Knight_335 Came to the N55 Darkside 1112 Rep 12,740 Posts Drives: 2011 335 E93 M-Sport Join Date: May 2010 Location: NY/NJ iTrader: (28)	I thought for sure my charge pipe bit it. Time to call the kind folks at P3!
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12-20-2015, 07:24 AM	#7
Welcome to NBA Jam Is it the shoes!? 3884 Rep 5,112 Posts Drives: (Sold) 2011 E92 335i ZMP 6MT Join Date: Mar 2014 Location: USA iTrader: (1)	Your turbo is spinning backwards, making negative boost. Be careful, the resulting vortex could cause your car to suck itself into a singularity, trapping you in a dimension where only reruns of the Seinfeld Soup Nazi episode are on every channel, and green is actually blue. Last edited by Welcome to NBA Jam; 12-20-2015 at 04:45 PM..
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12-20-2015, 02:38 PM	#8
jwzimm Colonel 687 Rep 2,770 Posts Drives: '16 M3 Join Date: Jun 2011 Location: Renton, WA iTrader: (17)	Lol! It is funny how new tech can make folks forget the old. Before the days of valvetronic the manifold pressure would be negative during low throttle and idle situations. The N55 still has a throttle plate but when things are working normally it is wide open allowing the valvetronic system to handle the load metering. It looks like you might be having either throttle closures due to over boost or something is amiss with your valvetronic system __________________ 2008 Honda S2000 - Current 2016 F80 M3 - SOLD!! 2011 e92 X-Drive Coupe - SOLD!!
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12-21-2015, 09:37 AM	#11
Rotary Rasp Lieutenant Colonel 241 Rep 1,857 Posts Drives: 2009 E92 335i 6MT Join Date: Aug 2008 Location: SoCal - Torrance iTrader: (6)	Isn't normal to have vacuum when you're off the throttle? __________________
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12-21-2015, 02:54 PM	#13
grizz311 Captain Rus 46 Rep 348 Posts Drives: 2012 335i coupe Join Date: Sep 2013 Location: Atlanta iTrader: (2)	I thought it was normal. My boosted 350z gauge always read negative psi when off throttle for the vacuum. I don't remember the numbers though. __________________ JB4 Stage2 / BBS / ST / Alpina B3 / BMS / AA / ER / VRSF / Remus
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12-21-2015, 04:06 PM	#15
weehe126 Brigadier General 1161 Rep 3,189 Posts Drives: 2017 340i Join Date: Apr 2014 Location: San Antonio iTrader: (2)	No it is not normal. Boost is taken from the TMAP sensor in the charge pipe. The cp never sees vac.
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12-22-2015, 09:54 PM	#17
weehe126 Brigadier General 1161 Rep 3,189 Posts Drives: 2017 340i Join Date: Apr 2014 Location: San Antonio iTrader: (2)	The N55 does not generate vacuum in the charge pipes. Look up a technical article on it. If it did have vacuum it would only be in the intake manifold, after the throttle body. Just think about it, where would a normal vac source be for a boost gauge? On the intake mani, not the charge pipe. The P3 gauge gets the info from the TMAP sensor on the CP from the CAN connection. Can you find a pneumatic boost guage for the N55 to source pressure from the intake mani?
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