Hardcoded lower TPS limit in ITB mode?

[tmbryhn]

Is there a hard-coded lower TPS limit in ITB mode on more recent firmware versions?

Whatever I try, I can't seem to get the TPS lower than 1% on my dual ETB setup. It's quite frustrating when you have one 54mm throttle plate per cylinder and can't get the idle down without retarding the ignition way too much

Current tune and logs:
https://www.rusefi.com/online/?vehicleName=Aurora&user_id=1083&sorts[uploadedMsq]=-1&sorts[uploadedLog]=-1

[AndreyB]

Yes there is 1% at https://github.com/rusefi/rusefi/blob/07201ae9791657c0a99a3720d1138adb768bc326/firmware/controllers/actuators/electronic_throttle.cpp#L344

While it was touched in March under https://github.com/rusefi/rusefi/pull/4004/files looks like it was there before. Not 100% sure when we got it.

[tmbryhn]

Is there a way to work around this lower limit? Through eg. Lua?
Or will there be considerations implementing a simple variable along the lines of "minimum TPS value" to be set manually in TS? Ideally with at least one decimal place so that one could enter eg. a value of 0,3%?

[AndreyB]

Cannot lua, clamping happens after Lua.

Yes should be configurable https://github.com/rusefi/rusefi/issues/4119 created your best bet is to chase Matt.

[tmbryhn]

Thanks

[mck1117]

How much timing pulling are we talking? Can you adjust the linkage so that 1% is actually fully closed, but not on the mechanical stop yet? The point of the 1% limit is to prevent jamming the throttle against the hard mechanical stop (same at the high end) to avoid integral wind-up.

[tmbryhn]

How much timing pulling are we talking? Can you adjust the linkage so that 1% is actually fully closed, but not on the mechanical stop yet? The point of the 1% limit is to prevent jamming the throttle against the hard mechanical stop (same at the high end) to avoid integral wind-up.

We're talking into the negatives to get idle close to 1krpm.

What linkage are you referring to? This is a dual ETB/DBW setup.

Before updating firmware, it seems I was able to close it to < 1%, which resulted in a better engine brake during coasting, and also a more crisp/responsive return to idle speed. I'd really like to have the option of setting lower TPS manually to eg. 0,3% or thereabout. I don't think there should be a problem with integral windup on eg a 0,3% setting, given that I seem to have less than 0,1% positional oscillation on the ETBs, but I might be missing a point here..

One 54mm throttle plate per intake port on a 2332cc engine is pretty large btw

[AndreyB]

i think it's done please give it a try

[tmbryhn]

Downloaded and updated the ECU. Looks good.
The setting is clearly visible under ETB page in TS, although just as an integer and not float, so can't fine-tune the lower limit.
I'll try with 0% for the time being. Thanks for the quick update. I'll post back once it's tested

[AndreyB]

just as an integer and not float, so can't fine-tune the lower limit.

That's an issue - just changed it to allow 2 digits and spelled out 0.01 as minimal value