Return to idle

[extraparts]

2020 Accord 2.0T 6MT. Loving the full throttle dampening disable & target boost ramp disable in the latest KTuner update.

My settings: Rev hang disable, boost target ramp disable, turbo response IIII, improved throttle fix I, throttle-only VSA, standard padding, disable throttle dampening, early spool, and flex fuel. These all work great. Rowing through the gears and rev-matching downshifts are excellent.

What I'm working with now is fuel cut settings to nerf the anti-stall that occurs just under 2000 RPM. Watching TunerView, deceleration above 2K RPM occurs at -12psi (186mbar). Below 1950rpm, the throttle opens to -11psi (255mbar). Perhaps this is an anti-stall measure. Actual idle is -10psi (324mbar).

If fuel cut isn't active, anti-stall opening/closing the throttle at 1950 causes bucking while decelerating (did this since new off the dealer lot). If fuel cut is active (29.4:1 AFR), the car decelerates smoothly through the anti-stall throttle transition.

If fuel cut is active for more than a second or so (still in closed loop), the ECU runs rich at tip-in (seeing 8:1 AFR) causing a stumble/bog until AFR corrects. This stumble is not so bad under 1950 RPM where vacuum is never low and driving is sedate, but is pronounced at speed on the road above 2000 RPM. If fuel cut is not active at speed, the tip-in following decel is smooth.

What I would like to have is either no anti-stall, or to have no fuel cut above anti-stall RPM (1951).

My fuel cut settings:
TPS vs. RPM: 0% TPS, 1100RPM. 1% TPS and above set to 6000 (idea is soonest-possible recovery).
ECT cut at 176: 1050 (all else stock)
ECT recover at 176: 1000 (all else stock)
Fuel cut delay: 0msec in all gears
MAP based low/high cam cut/recover: 1000-1950: 265mbar, 1951-6900: 50mbar (idea is no fuel cut above anti-stall RPM for smooth tip-in)

The TPS% seems to override MAP settings. At 50mbar setting at 1950rpm I'd expect no fuel cut at, say, 3000 but it happens anyway at 0% TPS. Idle recovery works fine with a little RPM blip at 1100 as fuel cut ends.

My next move is to set delay in gears 3-5 to 99999msec and accept I have to keep the revs up in gears 3+.

Is there an upper limit to fuel cut delay? Is there a way to get rid of anti-stall under 2000 RPM?

[KTuner]

You have control of the settings. Everything is actually a factory integration. We change nothing with any of that.

[extraparts]

Thanks for the reply. I totally get we're changing factory calibrations and not the underlying code behavior.

I'm still not clear on whether a really big delay number won't cause a software problem. Do you know if the memory address big enough for 5 digit delay numbers? Six? Is KTuner software doing input validation on the numbers? Do you know if the ECU is doing input validation checking? Wouldn't want to have a buffer overflow scenario and extra digits overwrite the next memory address. I imagine you addressed input validation on day 1 (and the Honda engineers did too), but I'd like to have some level of confidence instead of test-bricking my ECU (or activating time travel; seems like "time travel" would be better as a Quick Enable).

Thanks.

[KTuner]

32767 is a great number to use that would apply to a 16 bit value without going negative if it's signed.

[extraparts]

That's exactly what I needed, thank you.

[KTuner]

No problem