Open source Over Boost Fuel Cut
 

***Use at your own risk.***

This implementation hijacks the speed limiting fuel cut routine and assesses MAP instead of vehicle speed.

Defined for A00G/A01G ROM: a single value in the speed limiting fuel cut routine is changed (from 0x58 to 0x5A) to get MAP loaded instead of speed and MAP limits are entered in place of speed limits. To clarify, no additional patch is needed for this modification besides the single value switch in the code - thanks to Subaru engineers who just lifted the speed limit rather than write new code.

Defs and test log with 1.35 Bar cut limit and 4400 RPM active.
First ramp showing MAP > 1.35, RPM < 4400: No fuel cut.
Second ramp showing MAP > 1.35, fuel cut when RPM hits 4400.
Third ramp showing RPM > 4400, fuel cut when MAP hits 1.35.

This is a neck-snapping hard fuel cut, but probably better than a blown engine due to major overboost. Haven't done extensive testing and you'll lose your speed limiter fuel cut if you apply this (default set to fuel cut over 500 km/h).

Def for A00G/A01G:

Just realized that I set my cut and resume values the wrong way around during that test and in the above example, cut would be > 1.3 Bar with resume < 1.35 Bar (no hysteresis with values set as above).

Fantastic work! :clap:

You have email :)

I've sent Shiv addresses for OFT_B01C ROM to test (only for OFT 2.xx ROMs). If anyone else with FI running A00C or A01C ROM wants some addresses to test before general release, get in touch with me.

Also note above that I have defined MAP pressure for fuel cut rather than boost (MRP) pressure. Just so no-one gets ideas of running at 1.3 Bar Boost = 19psi Boost, I did my testing on low boost: 1.3 Bar MAP = 0.3 Bar Boost = 4.35 psi Boost.

Thank ztan, I'll be testing in our turbo car on Monday. Once again, fantastic work and big kudos on your desire to contribute to the open source community :thumbsup:

Shiv: thanks for the recommendation.

Nice! That's all my wife's doing. I haven't been to India in 10+ years! Have a great time :cheers:

ztan knocked it out of the park. I just tested his update in our turbo FRS and it works beautifully. So beautifully, that I'll be adding it to all OFT350 customer tunes. In the datalog below, I have the boost cut to set to 9psi:

http://datazap.me/u/shivvishnu/oft-z...=0&data=2-9-13

Great work ztan. The community appreciates it!

For those of you on B01C, this is what I sent to Shiv:

Note that I have set this .xml description to "boost" pressure in psi over atmospheric. Use the descriptor at the top of the post if you work in absolute Bar.

B01C:

this is great im going to need to add this to the sbd tune. would the same codes work on a A00c rom?

I don't think so, but I haven't checked A00C.
Send me a PM and we can work on pulling them for A00C.

Pulled on Grip Ronin's request for A00C/A01C, no feedback yet.

Can someone test and report on the following if you have FI and A00C or A01C (use one of the two .xml descriptors above):

ya turbos still in my living room. just finished porting the turbine housing and wg. still weeks away from install lol.

This is really great work man!! You're awesome!

This boost cut mod is working pretty well!
I modified A01E CAL ID rom file for this boost cut mod and got good result.
Boost cut activated at 8 psi and deactivated at 7.5 psi.

Attachment 161593
https://datazap.me/u/makinenkr/20180...zoom=2728-2758

It might need fine tuning of parameters to prevent boost fluctuation.

Good job @ztan !

Nice work,

you could likey just use the entire A01G rom in your car and get flexfuel as well

I've applied over boost fuel cut to and tested with Kouki K00G-based OTS ROM. It works as A01E or G.

Modifications for K00G
 

As @AussieBRZ mentioned this is required for K00G rom, I'd like to add my modifications for K00G. Any rom definitions based on K00G could work.

But as usual use this at your own risk.

This tweak works by toggling "Boost Limit (Fuel Cut) enable" which writes not a value byte but a code byte actually.

This is, apparently, completely unchanged all the way to V00C/U01A. And confirms something, since I have a variable there labeled "map_maybe". Thank you for posting this! For those who need it, then, here's the correct addresses for those (the rest of the definitions are unchanged as per above).

U01A:

V00C:

The exact bytes surrounding the 'enable' location are unchanged from A01C..V00C, so:

4c f0 ff cb ff eb ff fb d2 <Enable>58 fe 28 d2 58 fc 28 d2 58 ff 28 d2 58 42 4b d2 58 42 0b 6c 0c

Searching for those hex bytes in the file appears to return a single location in any BRZ gen1 ECU, and that first '58' in the command 'd2 58' is what the 'enable' entry modifies above. Similarly, this locates the other three addresses:

44 7a 00 00 44 7a 80 00 <Fuel Cut>43 fa 00 00 43 fa 00 00 43 f5 00 00 43 f5 00 00 <Resume>44 7a 00 00 <Active>45 89 80 00

(If you are not familiar with hex editing and can't recover from a bricked ECU, you probably shouldn't try to use this information, but if you understand what you're doing, this is perhaps hours to weeks of time saved. Cheers.)