openecu.org

Hi all.

I installed a perring big maf tube and wanted to rescale the Maf using the Air Flow Sensor Scaling Table.

I used XMLWRITE to create the XML file for my ecu, this works ok.

When I open the Table using Ecuedit (latest version) and insert the new values the values are stored in the table and the graph rises ok.

However when I save the ECU-File and reopen it all values in the table higher than 300 are not stored correctely, only the last two digits are stored, so I entered 307.95 and after save there is 7.95 in the table...
Does anyone know the problem since this messes up my mapping!
I will attach a picture of the graph after saving, the problem starts as soon as value 300 or higher needs to be inserted.

I hope someone has an idea!

PS my ECU type is A4RN1XXX

You can't rise MAF max value above 300g/sec.
The max ECU internal representation is 16-bit value FFFFh = 300g/sec

read this - http://forums.openecu.org/viewtopic.php?t=523&highlight=

if you cannot enter more than 300g/s then its a problem with the editing app.

calvin.

Ah, thanks Evoman!

Would you have any suggestions how to implement the big maf then?

Should I decreasing injectorsize in combination with rescaling the mass air to have it correct? (big maf air increase is not linear)

thanks

Barry

calvinc wrote:read this - http://forums.openecu.org/viewtopic.php?t=523&highlight=

if you cannot enter more than 300g/s then its a problem with the editing app.

calvin.

ignore my post.

calvin.

@ Calvin:

Nice to see the spreadsheet you made in Excel.
But how do I program the values exceeding 300g?

According to Evoman and my efforts the map does not accept numbers larger than 300?

Thanks, I apreciate!

Barry

PS It concerns an EU 2004 2.0 WRX STI

wrxsti wrote:
the map does not accept numbers larger than 300?
PS It concerns an EU 2004 2.0 WRX STI

Not only. This concern all Suba ECUs based on HC16 CPU.

There is a MAF measuring chain as follows:
MAF (0...5V) -> 10-bit CPU internal ADC -> Shift 6 bit left ADC result filling with nulls in low significant bits -> store new 16-bit value in RAM -> ECU calculations...
Now I'm parsing ECU disasm listing looking for some internal scale value.
If this ( or something similar) exist anywhere in program code, may be this will help to resolve a problem...

Nice to see the spreadsheet you made in Excel.
But how do I program the values exceeding 300g?

thanks but not possible unless an internal scaling value is found like evoman says...i havent done enough dissasembly to know yet.

calvin.

(NeverLies has done some great dissasembly and found the following )

it seems there is a scaling value for MAF, which is used in the engine load calculation. so therefore you're MAF g/s values would still appear the same but the 400g/s scaling value allows you to have a higher engine load computation which is then used in the fueling, ignition, vvt, etc. maps.

The following ROM revisions have a scaling value of 400g/s:
A4TJ111B (JDM MY05 STI (AJ810 8801)
A4TJ121B (JDM MY06 STI (AL300 2261)
A4TJ111C (JDM MY05 STI RAC (AJ820 8810)
A4TJ121C (JDM MY06 STI RAC (AL380 2270)
A4TJ120S (JDM STI S203)

calvin.

So nobody knows how to enter more than 300g/s?

Without a pretty hardcore hack of the way the ECU interprets the data, you can't. I just made a post one of the other forums, there is another active thread.

The messy, but working, hack is to put in a value that tells the ECU your injectors are smaller than they actually are, then keep your MAF scaling under the 292g/s limit. Say, even if your MAF scaling at 4.5v should be 340g/s, you keep it set to 280g/s (or whatever). What you'll have to keep in mind is that your airflow is going to always read lower than the actual physical airflow. You'll have to kinda fake it. In your timing map, 4.0 load might actually be 4.8 load and so forth. It's ugly, but it will work. Your logger will always report the lower, incorrect airflow and load numbers even if you hack up your XML.

You can still fine tune your injector scale and MAF table to make your fuel table to look reasonable and keep your fuel trims in check.