Barometric Correction

Tuning concepts, methods, tips etc.

Moderators: jsmcortina, muythaibxr

Post Reply
R100RT
Super MS/Extra'er
Posts: 1039
Joined: Thu Jun 30, 2011 12:45 pm
Location: British Columbia

Barometric Correction

Post by R100RT »

Greetings, just back from an epic road trip into the US "Four Corners" area where we saw some uterly amazing territory and riding.(Arizona, Utah, New Mexico, & Colorado)
Being as how we stopped/ camped at various points along the trip the old airhead was treated to increasingly higher altitudes and hence lower ambiant map readings for start up "snap shot".
Here's the deal, this is an initial post just to describe some findings and will be followed up more in depth with my trip "msq" etc.
Equally, I haven't done much for proving the "barometric corrrection" settings that I had adopted - living and riding pretty much @ sea level most of the time. Those settings were based on extensive forum searches, manual review, and what I found to be heated debate on what worked, and what should work.
Some of the locations we covered or stayed at were up and over 10,000ft and I've tuned at sea level. Consequently, what started to manifest was increasingly leaner fueling (although my EGO enabled corrections alowed the problem to mask up to about 4000ft I believe). Tough to handle twisties and steep grades when you're slipping towards 17 or 18 to 1 :(
Eventually the coin dropped and I knew what was happening, just how to deal with when many thousand miles from home and no access to a lap top was the question.
Much to the perplexity of my riding mates however, each time I did a restart I pulled the map sensor hose and would blow into it while a helper keyed on ignition. Not quite sure what reading this would be developing but pretty much satisfied my MS that we were at sea level and there were no alterations to the fueling and proper operation.
I am hoping to properly tune this and will be following with some further material.
Other's experiences or observations will be welcomed.

Lorne.
1983 BMW R100RT Motorbike
Turbocharged - Water/Meth
Sequential Ignition & Fuel
"Perky Sleeper" that excites bike enthusiasts once discovered (or being passed)
Newest project - 1995 BMW K75 is V3 Microsquirt, "Turbocharger - Of Course"
rabid
Experienced MS/Extra'er
Posts: 303
Joined: Mon May 09, 2005 7:44 am

Re: Barometric Correction

Post by rabid »

I think if the map reading is out of range then it will go to the default baro.
R100RT
Super MS/Extra'er
Posts: 1039
Joined: Thu Jun 30, 2011 12:45 pm
Location: British Columbia

Re: Barometric Correction

Post by R100RT »

Perhaps this will make sense to some, I'm not understanding the influence towards corrections to fueling having taken place when the below settings used.
On the below table found under Extended - "Non Linear Baro Correction", zero's are choosen for all pressure readings:
photo 1.JPG
On the below menu found under Tools/ Sensor Calibration/ Baro Correction I have 100% @ total vacume, and 0.0% @ rate (not that I really understand that):
photo 2.JPG
And the msq:
2015-08-09_14.56.59.msq Baro Correction.msq
Any thoughts?

Some example numbers as I understand altitude are:
Sea Level = 101kPa / 2000ft = 94.2kPa / 4000ft = 87.5kPa / 6000ft = 81.2kPa / 8000ft = 75.3kPa / 10,000ft = 69.7kPa
Rabid, a restart while at 8000ft would be a value not on the tables (75.3kPa) - how is the "default baro" then able to influence the fuel equation? I was noting correction issues even while at 4000ft which the 87.5kPa number would reside on the chart range. Just adding detail.

Seeing as how I had normal operation when I "blew" the map sensor towards thinking sea level while actually being @ 8,000ft for example, I'm really not thinking I need a correction and would like to dial that in on the MS2 Extra menus rather than one of my "add on" devices. What's the best way to achieve that (figured it was already done as such).
Comments welcomed.
Lorne
1983 BMW R100RT Motorbike
Turbocharged - Water/Meth
Sequential Ignition & Fuel
"Perky Sleeper" that excites bike enthusiasts once discovered (or being passed)
Newest project - 1995 BMW K75 is V3 Microsquirt, "Turbocharger - Of Course"
jsmcortina
Site Admin
Posts: 39612
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK
Contact:

Re: Barometric Correction

Post by jsmcortina »

I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
R100RT
Super MS/Extra'er
Posts: 1039
Joined: Thu Jun 30, 2011 12:45 pm
Location: British Columbia

Re: Barometric Correction

Post by R100RT »

Hello James,

Thanks for the link on the recent discussions.
If I might clarify how my engine behaved utilizing the "initial Map Reading" and having SD strategy, restarts as altitude increased resulted in leaner afr's, in every case. Additionally, my "blow into the map sensor hose" field fix although entirely unscientific allowed completely normal operation as if I was running at sea level, even while encountering heights of 10,000ft. My engine is turbocharged and perhaps the exhaust flow behaviour defies the norm (where readings should go rich)
Regardless, is the new firmware the item you post marked below:

The beta14plus firmware can be found here:
http://www.msextra.com/downloads/dev/ms ... ta-14plus/

If so, would that be allowing one correction only and hence with 100's entered not perform any corrections? (that's my object as I believe through observation of my engine through all these altitude regions that I do not require any correction).
Regards,

Lorne
1983 BMW R100RT Motorbike
Turbocharged - Water/Meth
Sequential Ignition & Fuel
"Perky Sleeper" that excites bike enthusiasts once discovered (or being passed)
Newest project - 1995 BMW K75 is V3 Microsquirt, "Turbocharger - Of Course"
jsmcortina
Site Admin
Posts: 39612
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK
Contact:

Re: Barometric Correction

Post by jsmcortina »

No need to use beta software, update to the current release.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
R100RT
Super MS/Extra'er
Posts: 1039
Joined: Thu Jun 30, 2011 12:45 pm
Location: British Columbia

Re: Barometric Correction

Post by R100RT »

I will update next opportunity then. And are there any tricks to nullifying the corrective behaviour? (stick with 100's in entry's etc.)
1983 BMW R100RT Motorbike
Turbocharged - Water/Meth
Sequential Ignition & Fuel
"Perky Sleeper" that excites bike enthusiasts once discovered (or being passed)
Newest project - 1995 BMW K75 is V3 Microsquirt, "Turbocharger - Of Course"
rabid
Experienced MS/Extra'er
Posts: 303
Joined: Mon May 09, 2005 7:44 am

Re: Barometric Correction

Post by rabid »

Last year I went to a race at low elevation. My upper limit kpa was set to 100 and my default baro was 88.9. I saw that my baro was 88.9 at near sea level but my map was reading 101. So I increased the upper limit to 111 just to get it to read in 101. This is initial map reading and I think it was 1.3 firmware for ms3. I'm saying that if you blew into the hose it might just use the default setting.

So blowing into the hose would result in a baro of 100kpa in your case. I assume you blew over 105kpa. Also, according to the directions, you should set correction at total vacuum to 0.
jsmcortina
Site Admin
Posts: 39612
Joined: Mon May 03, 2004 1:34 am
Location: Birmingham, UK
Contact:

Re: Barometric Correction

Post by jsmcortina »

R100RT wrote:And are there any tricks to nullifying the corrective behaviour? (stick with 100's in entry's etc.)
See the tooltips and manual.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: http://www.msextra.com/forums/viewtopic ... 04&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
New users, please read the "Forum Help Page".
R100RT
Super MS/Extra'er
Posts: 1039
Joined: Thu Jun 30, 2011 12:45 pm
Location: British Columbia

Re: Barometric Correction

Post by R100RT »

Thanks for your comments Rabid.
jsmcortina wrote:
R100RT wrote:And are there any tricks to nullifying the corrective behaviour? (stick with 100's in entry's etc.)
See the tooltips and manual.

James
:RTFM: - Force of habit, my bad. Obviously been a while and a full review in order.
Some really nice work on those & thanks for all your time towards a professional set of documents.
Lorne
1983 BMW R100RT Motorbike
Turbocharged - Water/Meth
Sequential Ignition & Fuel
"Perky Sleeper" that excites bike enthusiasts once discovered (or being passed)
Newest project - 1995 BMW K75 is V3 Microsquirt, "Turbocharger - Of Course"
Post Reply