OFT Tune Usefull Information and Tweaks

[Teseo]

Did I need a retune if I install aftermarket overpipe or frontpipe?

[tomm.brz]

if switching to a catless fp, it will throw a bit off the afr and change the knock resistance, definitely worth to take a look at logs and adjust

[gonzo]

Originally Posted by NoHaveMSG

steve99 was unfortunately banned. You can find him on the OFT FB group if you use FB. There are others here that can probably answer your question. I haven't touched any of that stuff since I had my car tuned but there are others who are very knowledgeable who may chime in and answer for you.

Reason for ban? Curious.

[Teseo]

Originally Posted by gonzo

Reason for ban? Curious.

Some asshat complained. Woke forum

[x808drifter]

Originally Posted by Teseo

Some asshat complained. Woke forum

Wouldn't say the forum is woke.
Shit there's alot of shit I wanna say that is way more non PC that the shit I type and what I do now is non PC to woke people.

[callisto]

Originally Posted by steve99

OFT Tune Tweeks and Information

Tweak to smooth low down Throttle response - alter the tip-in enrichment tables

The standard tip-in does not activate till 1.5% throttle delta AND the minium tip-in pulse width of 2.4ms is exceeded this means no tip-in till aprox 8% throttle delta. Changing the minimum pulse width activation to 1.5ms and a tweak to the enrichment tables will get the tip-in started at about 4% throttle delta. Smooths out low end throttle response and takeoff.

U01A (MY 20JP) uniquely among every version I've decoded reduces Minimum Tip-in Enrichment Activation to 1.2ms, beyond the 1.5ms recommended generally; so it seems that Subaru agrees with that change and takes it a step further. While they don't alter the enrichment tables as above, U01A does also add a unique alteration to Tip-in Enrichment Compensation B/C (ECT) that increases cold and decreases hot enrichment above 50% port injection, which seemed worth noting:

Tip-In Enrichment Compensation B, row 1.0 (100%): 40°C = -20%; 50° = -60; 60°–110° = -70.
Tip-In Enrichment Compensation C, row 1.0 (100%): -40°–0°C = 60%; 10° = 50; 20° = 40; 30-50° = 30.

[makinen]

Originally Posted by callisto

U01A does also add a unique alteration to Tip-in Enrichment Compensation B/C (ECT) that increases cold and decreases hot enrichment above 50% port injection, which seemed worth noting:

The A01G definition has no Port Injection Ratio index in those tables, then those Tip-in Enrichment Compensation B/C (ECT) can't be ported, or can we?

[callisto]

Originally Posted by makinen

The A01G definition has no Port Injection Ratio index in those tables, then those Tip-in Enrichment Compensation B/C (ECT) can't be ported, or can we?

Not without modifying the underlying code, no. That change was post-K00G (MY17-20) and isn't as simple as table hacking.

If you have the tools to unbrick your ECU — it involves both soldering and having an image of the first 8kb for pre-facelift, which I do supposedly have — or don't mind a 10-20%, in my personal experience to date, chance of your ECU being bricked because of an oversight or error on my part, then it's actually pretty easy to customize into an ECU. But it's only simple in theory, as in practice it costs 0-2 ECUs to get right, and while I'm pretty great at getting these right the first time, I'm not perfect at doing so.

[makinen]

Originally Posted by callisto

Not without modifying the underlying code, no.

I don't think those efforts are worthwhile.

Anyway, thanks for your hybrid works.

[Compelica]

Originally Posted by callisto

U01A (MY 20JP) uniquely among every version I've decoded reduces Minimum Tip-in Enrichment Activation to 1.2ms, beyond the 1.5ms recommended generally; so it seems that Subaru agrees with that change and takes it a step further. While they don't alter the enrichment tables as above, U01A does also add a unique alteration to Tip-in Enrichment Compensation B/C (ECT) that increases cold and decreases hot enrichment above 50% port injection, which seemed worth noting:

Tip-In Enrichment Compensation B, row 1.0 (100%): 40°C = -20%; 50° = -60; 60°–110° = -70.
Tip-In Enrichment Compensation C, row 1.0 (100%): -40°–0°C = 60%; 10° = 50; 20° = 40; 30-50° = 30.

In what circumstances that tables B and C are referenced?

[callisto]

Originally Posted by Compelica

In what circumstances that tables B and C are referenced?

It hinges on a single byte at A01G:fff8b613; if it's 0x01, then it selects tables Throttle Tip-in Enrichment A and Compensation B (ECT); otherwise, it selects tables Throttle Tip-in Enrichment B and Compensation C (ECT). The enrichment value selected is written to A01G:fff8ab08 and the comp (ECT) value to A01G:fff8ab0c (both floats).

A01G:fff8b613 is decided by function A01G:fbc78, but I haven't traced that yet myself. The XML defs don't say either.

That same byte (here, I switch to V00C since I haven't labeled A01G) is used during the closed-loop calculations; if 0x01, assuming other circumstances not described, it selects Input A Rising Load Activation ECT Load 1, 4, 6; otherwise, it selects 2, 5, 7; apparently 4 and 5 are mislabeled since they're ECT & PI ratio, not ECT & Load, lookups. Oops.

Also between two tables occurs in CL Fueling Transient Unknown M vs. L, with inputs delta-MAP & PI ratio.

Also between Tip-in Enrichment Disable Applied Counter Threshold & Throttle Cumulative Threshold tables A vs. B, looked up by ECT.

So, let's see.

  fVar3 = QUERY_3dmtable(xinput,fVar3,&Target_Throttle_Plate_Pos_Max_Req_Torque);
  fVar2 = bound_value(fVar3 + fVar4,0.0,fVar2);
  if (param_1 == '\0') {
    DAT_fff8b720 = fVar1;
    FUN_000aea8e(0x11);
    param_1 = '\x04';
    DAT_fff8b718 = ~(uint)xinput;
    DAT_fff8b71c = ~(uint)fVar2;
    FLOAT_fff8b6fc = fVar2;

Okay, so, here, it calculates a target throttle plate position, caps it at whatever the max is for .. whatever the inputs to that 3dmtable are .. and then writes the final target plate pos to A:b474 / V:b6fc. Which means that the decision between the two tip-in enrichment tables is, in somewhat more coherent code:

  if ((_in_neutral) || (_throttle_plate_target < 0.26)) {
    ENGINE_tip_in_BYTE_b417 = 0;

So, if you're in-gear and your requested throttle plate position is >= 26%, then A:b613 is 0x01, otherwise it's not.

Interesting! That compensation result is seemingly only used in one place, as part of calculating what I imagine is the extra fuel to be injected, since it later creates a copy of that amount with a compensation derived from injector latency and passes them both off to a CANbus function I haven't traced yet.

    _tip_in_enrich_comp_rpm = QUERY_2dtable(_rpm,&Throttle_Tip_In_Enrichment_Comp_RPM);
    _tip_in_enrich_comp_mrp =
         QUERY_2dtable(ENGINE_maprel_maybe,&Throttle_Tip_In_Enrichment_Comp_MRP);
    if (_tipin < 1.0) {
      fVar10 = ENGINE_tip_in_enrich * _tip_in_enrich_comp_rpm * _tip_in_enrich_comp_mrp *
               ENGINE_tip_in_enrich_ect;
    }
    else {
      fVar10 = ENGINE_tip_in_enrich * _tip_in_enrich_comp_rpm * _tip_in_enrich_comp_mrp *
               ENGINE_tip_in_enrich_ect * ENGINE_throttle_tip_in_enrich_comp_d_ect_result_acc4;
    }
    /* V00C as below; A01G fff8aae4 .. fff8aaf8 */
    FLOAT_fff8acbc = fVar10 * FLOAT_fff8acd0;

So it's just multiplied in along with the rest, and I bet this table definition is rewriting '100%' to '0%' to hide that this is just a ratio factor like all the rest.

expression="(x*.01220703125)-100"

Yep, sure enough, that -100 is the giveaway. Okay.

Restated, then:

When in-gear and with a throttle plate position of 26% or more, U01A uniquely:

- uses Tip-In Enrichment A; and Compensation B (ECT) with altered row 1.0 (100%) that reduces tip-in enrichment fueling: 40°C = –20% (0.8x); 50° = –40% (0.6x); 60°–110° = –30% (0.7x).

Otherwise, either in-neutral or with throttle plate below 26%, U01A uniquely:

- uses Tip-In Enrichment B; and Compensation C with altered row 1.0 (100%) that increases tip-in enrichment fueling: -40°–0°C = +60% (1.6x); 10° = +50% (1.5x); 20° = +40% (1.4x); 30-50° = +30% (1.3x).

I'll have to think for a while on why it might do that, but I'm right at the limits of both what I know about the ECU and what I know about tip-in enrichment tuning, so I'll stop without speculating further. Thanks for the good question!