HOWTO: One Man's Way of Scaling a MAF - Page 2

akira02rex · 01-24-2008, 12:10 PM

I'm lost LOL!

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akira02rex · 01-24-2008, 12:27 PM

Ok i figured it out, lot of work, but getting there!

williaty · 01-24-2008, 06:14 PM

OK, I was out driving today, and I just got back. Does anyone still need help at this point?

Rogan · 01-25-2008, 09:34 PM

will - what is the correlation of the A/F Learning #1 A-D? I mean, does "A" display the stored correction for a certain RPM vs TPS angle, like very light, <20% TPS angle, under 2500rpm? What about B, C, and D? Or am I wayyy off?

williaty · 01-25-2008, 10:20 PM

They're based off of MAF g/sec. A being the lowest (idle). You can look in your ROM to find out what the ranges are.

Rogan · 01-25-2008, 10:46 PM

ahhh... Duh me...

Code:

Min Range B/Max Range A    Min Range C/Max Range B    Min Range D/Max Range C
           5.60                     10.00                      50.00

so "A" is g/s idle to 5.6
"B" is 5.6 - 10.0
"C" is 10.0 - 50
"D" is => 50

?

Tea cups · 01-25-2008, 11:00 PM

Quote:

Originally Posted by bchslap

ahhh... Duh me...

You are using old definitions, BTW. The static labels are still correct in this example, though, but you should always use the latest.

D would be 50+

Rogan · 01-25-2008, 11:08 PM

hmm.. well, here's a question, then, Tea cups...

My def. file is for 400 g/s scaling.. How do I go about "updating" it? Or maybe I should put this Q in a different thread..

Tea cups · 01-25-2008, 11:37 PM

Send me a PM on the xpttuning site and I can send you an update.

williaty · 01-26-2008, 12:50 AM

Tea Cups, how could you tell his def file was outdated? My results look just like his and I've got the current defs.

Tea cups · 01-26-2008, 09:45 AM

Quote:

Originally Posted by williaty

Tea Cups, how could you tell his def file was outdated? My results look just like his and I've got the current defs.

I changed the labels to this in the newer defs. Same thing, but clearer:

Code:

 Max Range A / Min Range B   Max Range B / Min Range C   Max Range C / Min Range D

Bithell.Wagon06 · 01-26-2008, 01:05 PM

I have got a lot of reading to do!!!

williaty · 01-26-2008, 01:07 PM

let us know if you need help

p1prodrive · 01-26-2008, 06:21 PM

i better get reading

Wheeler Bement · 01-27-2008, 01:49 AM

williaty, since there is an IAT vs MAF compensated table...do you really need to do the temp. filtering? It would make sense to me that if the IAT temps rise, the compensatioin will "correct" something so the AFRC and AFRL will be the same. Otherwise, if I do this exercise at 50F, then I will have to do it again at 80F.

williaty · 01-27-2008, 01:04 PM

The IAT MAFv compensation table is at best a little off, and at worst complete and utter fiction. At least on my ROM, a 30F change in IAT will skew the total correction ~10-12%. As things warm up, I intend to fix it.

Bithell.Wagon06 · 01-27-2008, 09:02 PM

Quote:

Originally Posted by williaty

let us know if you need help

HELP!!!

Seriously i am trying to learn the tuning end of my car (hopefully to be able and tune my own ride) and every time I try to get to a starting point for learning, I realize I have not gone far back enough!

williaty · 01-27-2008, 09:09 PM

I can't stress enough how the best way to start is with a book like Engine Management: Advanced Tuning by Greg Banish. That book will get you to the point where you'll understand the basics and be ready to learn the Subaru-specific stuff.

Bithell.Wagon06 · 01-27-2008, 09:26 PM

Thank you!
I will see if I can get that from Borders online!
I think that is exactly my problem. I don`t really have the basic fundamentals of tuning down and I am cramming the subie specifics down my own throat and it`s not going so well. Thnak you!

$16 and change @ Amazon!

williaty · 01-27-2008, 09:30 PM

I like that one a lot. There's also one with a Focus on the cover that many people seem to like, but I'm not that impressed with. There were also two books on forced induction that were very well regarded back on enginuity.org, but I have no idea what they were because they don't apply to me

You'll probably want to look them over though. I'm sure if you start a thread asking about tuning books, they'll come up.

Bithell.Wagon06 · 01-29-2008, 01:15 AM

I`ll do a search. If I don`t find enough or consolidated then I will start a thread.
Thanks!

Riles · 01-31-2008, 10:08 PM

Great write up. One question though. Once I tune my MAF will it throw off any of my other tuning such as the tune that I have done to my injectors?

williaty · 01-31-2008, 10:13 PM

Sort of. You can adjust injector scaling to correct for fueling errors where the entire range of MAFv's is off by the same correction (in other words, if your error is a straight horizontal line injector scaling will move it up and down). If your error is a straight line, but diagonal, injector latency will allow you to adjust the angle to make it a horizontal line. MAF scaling will allow you to fix both of the above PLUS make an error line that isn't straight (peaks, valleys, etc) into a straight line.

If you're sure your injector scaling is already correct, just use MAF scaling to smooth out the peaks and valleys in your error line to get everything to settle in to zero.

Riles · 01-31-2008, 10:25 PM

Great, thanks for the info. I'm going to get started on this ASAP because once I tuned my injectors, I thought my MAF was fine but I realize that I need to do some fine tuning. Thanks man!

williaty · 01-31-2008, 10:34 PM

This should make it clearer.

OK, that's a graph of 3 different general shapes for fueling error graphs. Unfortunately, in the real world, you'll usually be seeing 2 or more of them going on at the same time

Error Type 1 is a vertical offset or zero error. The graph has a general trend all in one direction and basically all the same amount. This can be caused by things like incorrect injector scaling, placing the MAF in a different-than-stock sized housing or a new bend before the MAF. This can be fixed with either MAF scaling or Injector scaling. You should alter whichever scaling you've physically changed. This means that if you've just changed injectors, change the injector scaling. Likewise, if you've just altered the intake somehow, change the MAF scaling.

Error Type 2 is a slope error. The graph may or may not all be above or below zero, and it won't all the the same amount. What it will be is a straight line with a constant slope. This is likely caused by injector latency, but with how ornery MAFs are, I bet you could cause this to happen by changing the intake too. This can be corrected with either Injector latency or MAF scaling. Again, fix the scaling for whatever hardware you just changed.

Error Type 3 is a random error. The graph isn't a straight line, has peaks and valleys, and is in general just a mess. 9 times out of 10, this is the MAF being pissy about resonance and turbulence in its new home. This can only be fixed by MAF scaling. Adjust MAF scaling until the error is a straight line, then evaluate it for Type 1 or 2 error lurking within the MAF scaling corrections you just made. Again, if everything was alright before, and you just changed the intake, and then you got a bunch of fueling error, MAF scaling is what you want to change, not anything else.

So as you can see, you can fix any error with MAF scaling. It might not be the right way to do it though.

01-25-2008, 10:46 PM	#31
Rogan Scooby Specialist Member#: 142133 Join Date: Feb 2007 Chapter/Region: MAIC Location: Virginia - hate it Vehicle: 3 Jeeps And a Saab	ahhh... Duh me... Code: Min Range B/Max Range A Min Range C/Max Range B Min Range D/Max Range C 5.60 10.00 50.00 so "A" is g/s idle to 5.6 "B" is 5.6 - 10.0 "C" is 10.0 - 50 "D" is => 50 ?

01-31-2008, 10:08 PM	#47
Riles Scooby Newbie Member#: 121154 Join Date: Jul 2006 Chapter/Region: South East Location: Knoxville, TN Vehicle: 2002 Impreza WRX PSM Stage 47, Romraided	Great write up. One question though. Once I tune my MAF will it throw off any of my other tuning such as the tune that I have done to my injectors? Last edited by Riles; 01-31-2008 at 10:09 PM. Reason: cant spell

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01-24-2008, 12:10 PM	#26
akira02rex Scooby Specialist Member#: 82612 Join Date: Mar 2005 Chapter/Region: MWSOC Vehicle: '02 WRX - Sold Now 2013 WRX	I'm lost LOL! * Registered users of the site do not see these ads.

01-24-2008, 12:27 PM	#27
akira02rex Scooby Specialist Member#: 82612 Join Date: Mar 2005 Chapter/Region: MWSOC Vehicle: '02 WRX - Sold Now 2013 WRX	Ok i figured it out, lot of work, but getting there!

01-24-2008, 06:14 PM	#28
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	OK, I was out driving today, and I just got back. Does anyone still need help at this point?

01-25-2008, 09:34 PM	#29
Rogan Scooby Specialist Member#: 142133 Join Date: Feb 2007 Chapter/Region: MAIC Location: Virginia - hate it Vehicle: 3 Jeeps And a Saab	will - what is the correlation of the A/F Learning #1 A-D? I mean, does "A" display the stored correction for a certain RPM vs TPS angle, like very light, <20% TPS angle, under 2500rpm? What about B, C, and D? Or am I wayyy off?

01-25-2008, 10:20 PM	#30
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	They're based off of MAF g/sec. A being the lowest (idle). You can look in your ROM to find out what the ranges are.

01-25-2008, 11:08 PM	#33
Rogan Scooby Specialist Member#: 142133 Join Date: Feb 2007 Chapter/Region: MAIC Location: Virginia - hate it Vehicle: 3 Jeeps And a Saab	hmm.. well, here's a question, then, Tea cups... My def. file is for 400 g/s scaling.. How do I go about "updating" it? Or maybe I should put this Q in a different thread..

01-25-2008, 11:37 PM	#34
Tea cups Scooby Specialist Member#: 103136 Join Date: Dec 2005	Send me a PM on the xpttuning site and I can send you an update.

01-26-2008, 12:50 AM	#35
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	Tea Cups, how could you tell his def file was outdated? My results look just like his and I've got the current defs.

01-26-2008, 01:05 PM	#37
Bithell.Wagon06 Scooby Newbie Member#: 129790 Join Date: Oct 2006 Chapter/Region: BAIC Location: norcal Vehicle: 2006 VF39 WRX Waygon XPT Boooosted!	I have got a lot of reading to do!!!

01-26-2008, 01:07 PM	#38
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	let us know if you need help

01-26-2008, 06:21 PM	#39
p1prodrive Scooby Newbie Member#: 149827 Join Date: May 2007 Location: united kingdom Vehicle: 2000 600 bhp p1 sonic blue	i better get reading

01-27-2008, 01:49 AM	#40
Wheeler Bement Scooby Specialist Member#: 15652 Join Date: Feb 2002 Chapter/Region: TXIC Location: sugar land, katy Vehicle: 2002 2.5L WRX Wag. 160K club	williaty, since there is an IAT vs MAF compensated table...do you really need to do the temp. filtering? It would make sense to me that if the IAT temps rise, the compensatioin will "correct" something so the AFRC and AFRL will be the same. Otherwise, if I do this exercise at 50F, then I will have to do it again at 80F.

01-27-2008, 01:04 PM	#41
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	The IAT MAFv compensation table is at best a little off, and at worst complete and utter fiction. At least on my ROM, a 30F change in IAT will skew the total correction ~10-12%. As things warm up, I intend to fix it.

01-27-2008, 09:09 PM	#43
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	I can't stress enough how the best way to start is with a book like Engine Management: Advanced Tuning by Greg Banish. That book will get you to the point where you'll understand the basics and be ready to learn the Subaru-specific stuff.

01-27-2008, 09:26 PM	#44
Bithell.Wagon06 Scooby Newbie Member#: 129790 Join Date: Oct 2006 Chapter/Region: BAIC Location: norcal Vehicle: 2006 VF39 WRX Waygon XPT Boooosted!	Thank you! I will see if I can get that from Borders online! I think that is exactly my problem. I don`t really have the basic fundamentals of tuning down and I am cramming the subie specifics down my own throat and it`s not going so well. Thnak you! $16 and change @ Amazon!

01-27-2008, 09:30 PM	#45
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	I like that one a lot. There's also one with a Focus on the cover that many people seem to like, but I'm not that impressed with. There were also two books on forced induction that were very well regarded back on enginuity.org, but I have no idea what they were because they don't apply to me You'll probably want to look them over though. I'm sure if you start a thread asking about tuning books, they'll come up.

01-29-2008, 01:15 AM	#46
Bithell.Wagon06 Scooby Newbie Member#: 129790 Join Date: Oct 2006 Chapter/Region: BAIC Location: norcal Vehicle: 2006 VF39 WRX Waygon XPT Boooosted!	I`ll do a search. If I don`t find enough or consolidated then I will start a thread. Thanks!

01-31-2008, 10:13 PM	#48
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	Sort of. You can adjust injector scaling to correct for fueling errors where the entire range of MAFv's is off by the same correction (in other words, if your error is a straight horizontal line injector scaling will move it up and down). If your error is a straight line, but diagonal, injector latency will allow you to adjust the angle to make it a horizontal line. MAF scaling will allow you to fix both of the above PLUS make an error line that isn't straight (peaks, valleys, etc) into a straight line. If you're sure your injector scaling is already correct, just use MAF scaling to smooth out the peaks and valleys in your error line to get everything to settle in to zero.

01-31-2008, 10:25 PM	#49
Riles Scooby Newbie Member#: 121154 Join Date: Jul 2006 Chapter/Region: South East Location: Knoxville, TN Vehicle: 2002 Impreza WRX PSM Stage 47, Romraided	Great, thanks for the info. I'm going to get started on this ASAP because once I tuned my injectors, I thought my MAF was fine but I realize that I need to do some fine tuning. Thanks man!

01-31-2008, 10:34 PM	#50
williaty Scooby Guru Member#: 71092 Join Date: Sep 2004 Chapter/Region: MWSOC Location: Delaware County, Ohio Vehicle: 2005 2.5RS Wagon Regal Blue Pearl	This should make it clearer. OK, that's a graph of 3 different general shapes for fueling error graphs. Unfortunately, in the real world, you'll usually be seeing 2 or more of them going on at the same time Error Type 1 is a vertical offset or zero error. The graph has a general trend all in one direction and basically all the same amount. This can be caused by things like incorrect injector scaling, placing the MAF in a different-than-stock sized housing or a new bend before the MAF. This can be fixed with either MAF scaling or Injector scaling. You should alter whichever scaling you've physically changed. This means that if you've just changed injectors, change the injector scaling. Likewise, if you've just altered the intake somehow, change the MAF scaling. Error Type 2 is a slope error. The graph may or may not all be above or below zero, and it won't all the the same amount. What it will be is a straight line with a constant slope. This is likely caused by injector latency, but with how ornery MAFs are, I bet you could cause this to happen by changing the intake too. This can be corrected with either Injector latency or MAF scaling. Again, fix the scaling for whatever hardware you just changed. Error Type 3 is a random error. The graph isn't a straight line, has peaks and valleys, and is in general just a mess. 9 times out of 10, this is the MAF being pissy about resonance and turbulence in its new home. This can only be fixed by MAF scaling. Adjust MAF scaling until the error is a straight line, then evaluate it for Type 1 or 2 error lurking within the MAF scaling corrections you just made. Again, if everything was alright before, and you just changed the intake, and then you got a bunch of fueling error, MAF scaling is what you want to change, not anything else. So as you can see, you can fix any error with MAF scaling. It might not be the right way to do it though.