MAF Scaling - Open/Closed Loop Fueling info

[srscion]

I just noticed something my rom end with F00C, I cross-referenced roms that are AOOC+ and there is the option to disable p0068 in romraider, but not in mine. Its possible my map sensor may be a defect. But first I will try altering the CEL limits again to see what happens.

[zc06_kisstherain]

before bitching at me not knowing anything first. i am a total noob and never edit any tune before.

i usually let someone do maf scaling or fixing my tune but i want to learn!!
I downloaded this maf scaling tool v.24.1 and what do i do?
i ran program and how to import log info. i was like WTF!!! lol

I am mechanic savy but not software like this lol

[Spuds]

Originally Posted by zc06_kisstherain

I downloaded this maf scaling tool v.24.1 and what do i do?

For each horizontal tab (sections of the application) at the top of the tool, there are vertical tabs down the side. One of the vertical tabs in each section has instructions for that section.

[zc06_kisstherain]

Originally Posted by Spuds

For each horizontal tab (sections of the application) at the top of the tool, there are vertical tabs down the side. One of the vertical tabs in each section has instructions for that section.

i know but difficult to understand what to do...
i am quite computer savy..
how load up logs to adjust anything?

[Spuds]

Originally Posted by zc06_kisstherain

i know but difficult to understand what to do...
i am quite computer savy..
how load up logs to adjust anything?

If you are asking how to get logs on to your computer, then you aren't quite ready for maf scaling yet. Look up "subaru data logging" "Subaru rom editor" "flashing an ECU" "romraider" "ecuflash" "tactrix" "openflash tablet". That should give you the basics.

Also, there is this sticky http://www.ft86club.com/forums/showthread.php?t=29340

[zc06_kisstherain]

Originally Posted by Spuds

If you are asking how to get logs on to your computer, then you aren't quite ready for maf scaling yet. Look up "subaru data logging" "Subaru rom editor" "flashing an ECU" "romraider" "ecuflash" "tactrix" "openflash tablet". That should give you the basics.

Also, there is this sticky http://www.ft86club.com/forums/showthread.php?t=29340

I already read these and asking someone to guide me lol
but guiding and educating is different story.
we all shouldnt go to school if textbook is what we all need.
i am not really super duper total noob...have little basic knowledge on looking at datalogging..

anyway, thanks.

maybe i am stupid lol

[Kodename47]

I just wanted to add this info as it seems to be a massively overlooked effect of MAF scaling as many look to MAF scaling as a 1 step fix.

Below we'll use an exaggerated example situation that the engine is being held at 0.9 load and 2600 RPM.

Here's the fuel and ignition maps on the original MAF scale.


We can see that the fueling target is 14.0:1 and the base timing is 2.35 degrees advance. Now lets say that the fueling error works out to be around -15% (AFR too rich) and you adjust the MAF scale to that effect. Due to the MAF re-scale the engine load calculations will also end up having the same reduction, so now at the same situation your load is now around 0.75

MAF Scale Reduced 15%


This correlates to the same MAF voltage so the same actual airflow as above however you are now targeting 14.6:1 and base timing advance of 13.95 degrees. That means despite the same conditions in the cylinder you are now targeting a leaner AFR and nearly 11.5 degrees more advanced timing. Now lets swing the MAF up 15% the other way as if the fuel error was lean.

MAF Scale Increased 15%

Targets of 13.6:1 AFR and base timing advance of 0.23 degrees.

Now I know that my example is a little extreme and if you're not changing intake you wont get error like that, however I have just rescaled an intake where the original is around 15% out under WOT conditions. Even in my 1st example that a -5% change in MAF scale from the original would result in 4 degrees of extra advance. For those having a working tune that then starts to pull timing after a MAF re-scale then this could well be the cause.

All this needs to be taken into account when you play with your MAF and is one of the reasons that when you want to correct your OL MAF scale, if you've got all your load dependent settings (timing, cams, load limits, injection control etc) set then changing your MAF scale might not be the solution that you want to do.

[ELorinD86]

Steve99
I've read your advice over and over about how to not get the lump at 3v when doing open loop, but I must be mixing it up. When you talk about the columns to look at to set a good percentage do you mean the columns in the data log sheet or something else? I set what I was assuming is the throttle error % to 7.5 but I still get a big lump. Another reason I'm assuming I'm looking at the wrong thing to change this is default percent was 30% not 200%

[Kodename47]

Originally Posted by ELorinD86

Steve99
I've read your advice over and over about how to not get the lump at 3v when doing open loop, but I must be mixing it up. When you talk about the columns to look at to set a good percentage do you mean the columns in the data log sheet or something else? I set what I was assuming is the throttle error % to 7.5 but I still get a big lump. Another reason I'm assuming I'm looking at the wrong thing to change this is default percent was 30% not 200%

Have a look at this:
http://www.ft86club.com/forums/showthread.php?t=119535

[steve99]

Originally Posted by ELorinD86

Steve99
I've read your advice over and over about how to not get the lump at 3v when doing open loop, but I must be mixing it up. When you talk about the columns to look at to set a good percentage do you mean the columns in the data log sheet or something else? I set what I was assuming is the throttle error % to 7.5 but I still get a big lump. Another reason I'm assuming I'm looking at the wrong thing to change this is default percent was 30% not 200%

I wrote that a long time ago, the VGI program has has a lot of revisions and refinements since then, the defaults have likely changed.


have a look at wayno guide
http://www.ft86club.com/forums/showthread.php?t=94822


if your stock intake id grab his maf scale as starting point and then you may only need to tweak the open loop section above 3.2v

[steve99]

Originally Posted by Kodename47

I just wanted to add this info as it seems to be a massively overlooked effect of MAF scaling as many look to MAF scaling as a 1 step fix.

Below we'll use an exaggerated example situation that the engine is being held at 0.9 load and 2600 RPM.

Here's the fuel and ignition maps on the original MAF scale.


We can see that the fueling target is 14.0:1 and the base timing is 2.35 degrees advance. Now lets say that the fueling error works out to be around -15% (AFR too rich) and you adjust the MAF scale to that effect. Due to the MAF re-scale the engine load calculations will also end up having the same reduction, so now at the same situation your load is now around 0.75

MAF Scale Reduced 15%


This correlates to the same MAF voltage so the same actual airflow as above however you are now targeting 14.6:1 and base timing advance of 13.95 degrees. That means despite the same conditions in the cylinder you are now targeting a leaner AFR and nearly 11.5 degrees more advanced timing. Now lets swing the MAF up 15% the other way as if the fuel error was lean.

MAF Scale Increased 15%

Targets of 13.6:1 AFR and base timing advance of 0.23 degrees.

Now I know that my example is a little extreme and if you're not changing intake you wont get error like that, however I have just rescaled an intake where the original is around 15% out under WOT conditions. Even in my 1st example that a -5% change in MAF scale from the original would result in 4 degrees of extra advance. For those having a working tune that then starts to pull timing after a MAF re-scale then this could well be the cause.

All this needs to be taken into account when you play with your MAF and is one of the reasons that when you want to correct your OL MAF scale, if you've got all your load dependent settings (timing, cams, load limits, injection control etc) set then changing your MAF scale might not be the solution that you want to do.

Another demonstration of why almost all intakes on NA cars are way more trouble than their worth, especially stuff like the 3" maf tube ones that throw the maf scaling way off and require almost a total retune ( not just maf scale) to get working correctly for minimal gain

[Boomerang]

Does it matter if I do the logging when my IAM is dropping?

[Kodename47]

Originally Posted by Boomerang

Does it matter if I do the logging when my IAM is dropping?

No

[tomm.brz]

Originally Posted by Kodename47

No

But there is the "Fuel map - compensation" that enrich the afr based on IAM...