Coding for Ethanol based scalings
 

Coding for Ethanol based scalings (A01G ROM base)

The code below returns and stores a few values based on ethanol content; will describe how to modify ROM and do cranking comp to use these later on:

The clutch switch has been added to use as a failsafe in case the code added after is no good for testing purposes so fewer ECUs get bricked - the code only executes if clutch is depressed. Change the "branch if true" instruction at B97E6 to "00 09" (nop) to turn this switch off.

Initially the ethanol value in fr9 in passed to fr4 and this value is limited by the Check_Bounds routine at 011260 (max value in fr6 and min value in fr5)

The value returned in fr0 (Ethanol content) is stored to RAM_Ethanol and a Fuelling Multiplier is looked up from that table (E0=1.00, E85=1.40 in linear scale)

This value is used to multiply the PI Injector Flow Scaling BRZ value for Port injector operation and a GDI multiplier that works on GDI pressure multiplier tables A and B (I call this GDI multiplier C).

An interpolating value is then looked up in a table to scale between 2 Primary OL fuelling tables (E0=0.00, E85=1.00).

A further interpolating value is looked up for use between 2 base timing tables (E0=0.00, E85=1.00) which are then added to the Knock Correction advance table which remains un-modified. This interpolation value is multiplied by the AVCS active value (0.00 = AVCS not active (looks up Base Timing A), 1.00 = AVCS active (looks up Base Timing B) to use the E0 map as a AVCS inactive map also.

Theoretical table values input in image below. Please feel free to contribute data to discussion as to how best to scale these multipliers or interpolants to hit optimal fuelling and MBT with the 12.5:1 compression ratios with or without boost.

@ztan
Any reason you chose to use the DI fuel pressure signal instead of the injector PW to mass scaling like you plan to do for PFI?

Because it's probably the simplest way and is in effect doing the same thing. Have you looked at how to change direct injection PW yet?

The logic behind GDI quantity is not entirely teased out, but the value that I chose for GDI scaling is a single one that acts on both GDI pressure multiplier tables.

Previous open source E85 implementations have multiplied the result in the GDI pressure multiplier tables A and B (Axes are engine load and fuel pressure) to come up with a value that, I understand, approximates DI quantity. I did disassemble the ROM to find the derivation of the axes in another post: http://www.ft86club.com/forums/showthread.php?p=2387636

The value from the GDI pressure multipliers A and B then gets multiplied by a scaling factor (GDI pressure multiplier C which I am using to scale for E85). I believe that this is the scaling factor that changes the number from a fuel quantity to a pulsewidth value.

This raw DI pulsewidth value is then passed to the GDI flow rate table which is what is used to finalize the DI pulsewidth (compensations for quantity on one axis and fuel pressure on the other).

Awesome! Thanks for taking the time to explain it. So with this changed we do not have to rescale the MAF for E85 if I am not mistaken.
From experience the MBT spark timing does not shift so much for E85 to command any attention. It is just the actual spark timing that shifts. Some OEMs have MBT spark timing as a table in the ECU which makes it easy for tuners to tune for E85 because you just have to make the Base spark = MBT spark.

@ztan

So theoreticly on an A01G rom i could test this without a flex kit by making up a simple circuit to feed in 0 to 5 volts onto the evap input pin.

Or just a switchable voltage divider with say 0 ,2.5 and 5 v and effectivly map switch between E85 e40 and petrol.

assume you have added an extra Base TimingB and OL fuel map somewhere ?

ztan is a freakin' rock star :party0030:

Yes.
All to be revealed after more testing etc... but in short:

Base Timing A only gets used when AVCS off. FFF8ADB8 reads 0 when inactive (after ECU reset for a couple of minutes) and 1.0 when AVCS active. The value at FFF8ADB8 is use to interpolate between Base Timing A and Base Timing B. My plan is to hijack Base Timing A as E0 and Base Timing B as E85.

Primary OL Fueling map is added to by the OL Fueling additive map on the basis of IAM value (no additive applied when IAM = 1.0, full additive when IAM=0.0). I am going to assume, rightly or wrongly, that folks who are applying this have the nouse to be monitoring IAM and that IAM will not drop far enough below 1.0 to require extra fuel. Hence I would plan to use Primary OL Fueling map for E85 and OL Fueling additive map for E0 with above interpolant values.

It would be quite easy to add in completely new tables for the above, but this is the way I am thinking.

No MAF rescaling needed - we have reasonably good fuel control, although a little more complex due to having DI and PI systems to understand, and there are a lot of compensations applied to these values which are not clearly defined.

Unfortunately MBT spark is not visible in the ROM that I can find. I assume Shiv's E85 NA ROM will be pretty close on the money and hopefully we get some more data on where MBT lies higher in the load range on boosted engines in the future.

@ztan

For E85 cranking @Wayno s tables are very reliable even on united E85

E85 Cranking changes

0C/32F stock values multiplied x 1.5
10C/50F stock values multiplied x 2.0
20C/68F stock values multiplied x 2.0
30C/86F stock values multiplied x 1.3
40C/104F stock values multiplied x 1.2
50C/122F stock values multiplied x 1.1
60C/140F stock values multiplied x 1.05


http://www.ft86club.com/forums/attac...1&d=1442118398



For Dash fuel display multiply be 33% ie same ratio as GDI pressure multiplier offset or PI injector scaling offset.

http://www.ft86club.com/forums/attac...1&d=1442115733

Thanks, and thanks for the donation mate.

My idea is to hijack the IAT cranking compensation table (returns 1.0 across the board for all IAT values) part of the routine and use that as an ECT cranking compensation. This sits just below the accel cranking compensation in the code (the latter table returns 0.0 when the accelerator is fully down when cranking and no fuel is delivered).

I am thinking:
We want a cranking multiplier of 1.0 with E0 and ECT compensation to be applied with higher E%, based on the Flex scaling multiplier.

One way to do the maths is to return a multiplier of 1.0+((Flex scaling multiplier - 1.0)*ECT cranking multiplier). At E85 with a Flex scaling multiplier of 1.4, this would give us a cranking multiplier of 1.4 at 20C with the table that I posted in post #15. A table value of 2.5 would return 2.0 as a cranking multiplier.

This one is easy - get the normal table return and multiply it by the Flex scaling multiplier. The code would involve hooking the table lookup, scaling with multiplier and returning with all the values in the expected registers.

Their is also another Cranking compensation table relative to Intake Air Temp, in stock roms its all zero.

It might be easier to rescale and offset the IAT vs Cranking IPW table rarther than the cranking Vs Coolant tables.

have you seen kodename47 defs he has intergrated the opensource stuff with Ecutek stuff
http://www.ft86club.com/forums/showp...&postcount=411

I use Kodename47s defs which get modified each time I disassemble something that makes more sense in my head. I haven't actually kept track of which tables I've altered and which I haven't...

That IAT cranking compensation table that reads 0.0 in Kodename47's def means 0% compensation applied. When looking at the disassembly and running that bit of code through the HEW simulator, that table returns a value of 1.0 (scaling factor 1.0 = 0% compensation). I changed my def to suit as well as started thinking in terms of scaling factors rather than % compensation.