[SpartanSv]

My current setup is a Ford 5.4 32V V8 with a T67 turbo and E85 with a Speeduino 0.3 board. I'm on December 2020 firmare. I recently started refining my tune and one of the things at the top of the list was to dial in closed loop boost control.

What I've discovered is that when using closed loop boost control the Speeduino will not trigger the boost control output until MAP exceeds 100kpa. That's fine at sea level but less than ideal at elevation. My baro readings at my elevation are in the low 80s.

In my case the result is having to rely on spring pressure to hold the wastegate shut between ~82kpa and 100kpa. This is potentially problematic when running a very light wastegate spring.

What I propose is activating the boost control output as soon as MAP is greater than BARO instead of waiting until MAP reaches 100kpa.

[theonewithin]

Tried latest firmware?

No point reporting a bug that may only exist on older firmware

[SpartanSv]

No I haven't tried the latest, but I have read all of the changelogs.

Not much point in changelogs if you don't mention all of the changes......

[theonewithin]

So update your firmware?

Also wouldn't 80kpa manifold pressure be no different if its under boost or not?

Not even sure if it would be a bug or misunderstanding on how things actually work?

Either way you need to update your firmware.

[SpartanSv]

So update your firmware?

Ok I will, but what do you think that will accomplish? The changelogs don't mention anything about this.

Also wouldn't 80kpa manifold pressure be no different if its under boost or not?

Not even sure if it would be a bug or misunderstanding on how things actually work?

I think you're not understanding the issue. A worst case example is someone at 80 kpa baro trying to run a 15 kpa spring with something like a 30 kpa target. The spring won't get them to 100kpa so the boost control output would never be triggered and they would never see more than spring pressure.

[jonbill]

It's definitely deliberate:
auxiliaries.ino:162 from 202103 release:

Code: Select all

    else if (configPage4.boostType == CLOSED_LOOP_BOOST)
    {
      if( (boostCounter & 7) == 1) { currentStatus.boostTarget = get3DTableValue(&boostTable, currentStatus.TPS, currentStatus.RPM) * 2; } //Boost target table is in kpa and divided by 2
      if(currentStatus.MAP >= 100 ) //Only engage boost control above 100kpa.

Easy enough to try your own fix, and if it works, submit a pull request.

I'm inclined to agree it should be currentStatus.baro, but I don't know enough about how it all works to be sure.
I can't think why to use 100kpa other than as a cheap proxy for atmospheric pressure.

[SpartanSv]

Fantastic. Looks like it was just an oversight and appears to be extremely easy to change.

Thank you very much for pointing me in the right direction. I'll attempt to change it and report the results.

[SpartanSv]

I finally took the time to try this and it works perfectly. I simply changed the value of 100 to currentstatus.baro and closed loop boost now starts outputting to the solenoid as soon as MAP > barometric pressure.

Thank you very much jonbill.

[jonbill]

thats good news.