Scan Gauge and Boost ?

AUGSX

Veteran Member
Joined
May 7, 2007
Location
Miami, Fl.
TDI
2001 Jetta GL TDI 5spd
So my Scan Gauge II shows a MAP of 14.7 or there abouts at Idle, my question is when it reads 19.7 how much boost is the engine actually seeing?
5psi?

Sorry for the newb post from a veteran but I have always had my doubts about this and I figure I would just ask.
 

Digital Corpus

Top Post Dawg
Joined
Mar 14, 2008
Location
Ontario, California
TDI
'97 B4 w/ 236K mi body, 46K mi soul
That is correct. The sensor is referred to as a MAP, or Manifold Absolute Pressure, sensor. Subtracting the pressure at idle is exactly how you see what the turbo is producing.
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2005 BEW Wagon
Normal atmospheric pressure at sealevel is 14.7 psi but what you will read will depend a little bit on your altitude and local weather. As the barameter goes up and down so with the absolute pressure shown by the Scan Gauge.

Many people with a Scangauge code a custom readout (search for X-gauge) for boost... subtracting the average barometric pressure automatically.

Standard analog boost gauges show relative pressure rather than absolute, so automatically take local barometric pressure into account.
 

Airstream

Veteran Member
Joined
Aug 17, 2011
Location
Nashville, TN
TDI
2000 Jetta; 2010 JSW
Do some of the newer ones automatically figure all of this out? Mine had boost built in and seems to read it correctly. It at times reads (-.1) at idle but otherwise it seems correct, but it came like this. How accurate is it? I am stock and seek boost peaks up to 17.9...

If only it would update much faster.
 

AUGSX

Veteran Member
Joined
May 7, 2007
Location
Miami, Fl.
TDI
2001 Jetta GL TDI 5spd
Thanks for the replies guys, finally have the car back to 100% and this seems to be about right.
 

LMJ

Veteran Member
Joined
Feb 22, 2010
Location
Virginia
TDI
2000 VW Golf
How/where can i get it upgraded? The SG site only has updates for pre2011 versions
Get the form off of scangauge's webpage, send it back to scan gauge with a a check for $25. got mine back in just a few days.
 

Diesl

Veteran Member
Joined
Dec 3, 2012
Location
Chicago
TDI
'78 Golf Diesel (long gone); 2012 Jetta Sportwagen TDI w/ DSG
How/where can i get it upgraded? The SG site only has updates for pre2011 versions
If yours is newer and already has the latest firmware version, then you could define an XGauge (using the instructions on the scangauge website) and subtract atmospheric pressure yourself. I think abacus' instructions (with the TXD starting with 68) are for older non-canbus VWs. I'm not sure which year is the transition to canbus. Canbus XGauge definitions for 2009+ TDIs can be found in the 'scanners/gauge monitors for 2012 TDI' thread.
 

KZL_05TDI

Member
Joined
Jul 4, 2012
Location
Fort Collins, CO
TDI
2005 Golf GLS TDI Manual
so this actually really helps; I have a ScanGaugeII on my TDI too... I was wondering if I even have the setup correct on it for our cars? do we have to do anything special with it?
 

hotpocketdeath

Veteran Member
Joined
Mar 18, 2010
Location
Suwanee, GA
TDI
2010 Golf TDI
Ugh, no offense, but I would hate to have to do it that way.

This is why I enjoy using "Torque". I have a custom gauge that reads the MAP and subtracts the real time barometric pressure from my Android phone. The developer showed me how to add in variables from other sensors into the equations.

This way it auto adjusts whether or not I am in the mountains or driving along the ocean coast.
 

LMJ

Veteran Member
Joined
Feb 22, 2010
Location
Virginia
TDI
2000 VW Golf
so this actually really helps; I have a ScanGaugeII on my TDI too... I was wondering if I even have the setup correct on it for our cars? do we have to do anything special with it?
all you have to do is send it back to scangauge for an upgrade, then it will display Boost. see their web page or give them a call/email.
 
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