STFT Openloop

[Street Legal]

quick question about enabling the STFT openloop..in this situation when i enable the STFT during the openloop operation is it going to force the EQ RATIO table to be 14.7 ? or it is going to correct for commanded A/F in the table if the acutal is different ?

[gmforlife]

From what i've heard, when you are in open loop you would want to set your FT enable ECT and what not too a really high enable so that it wont affect your commanded A/F. I'm sure someone will chime in who will know for sure.

[EC_Tune]

If you have STFT Open Loop enabled it's just like being in Closed Loop without LTFT's.

[dr.mike]

Pardon the thread necromancy.

I have "STFT Openloop" enabled. And, I am seeing something odd in my logfiles.

During normal closed-loop operation, is see a, more or less, constant oscillation of the AFR from about lambda 0.99 to lambda 1.02. At low RPM, the period of oscillation is from 0.4s to 2.0s. And the period varies with the RPM. This all seems normal/fine.

But, when I am in open-loop PE, I see an oscillation, from about lambda 0.76 to lambda 0.78. But, at a much shorter period.

In fact, when I measure the period, it is ALWAYS the period of the engine speed. i.e.

If the RPM is 3000rpm the period is 40ms, etc If RPM is 5000, the period is 24ms, etc. This follows through the whole PE RPM range.

There is no way for the wideband to know the engine RPM. And, this is digital data. So, it's not coupled noise.

Do the STFTs add/remove fuel on a per-cycle basis under PE ? Originally, I thought this might be an exhaust leak issue.
But, that all seems to be buttoned up tight.

If you look at the pic, the timescale is 500ms/div There are right about 11 cycles per division. so, ~45ms period.
Sure enough, the RPM over that period is 2650rpm

oscillation.jpg

Will turning off "STFT Openloop" eliminate this ?

[chevy 6.0]

On my 6.0 the STFT turns off automatically whenever its in PE mode.

[dr.mike]

Thanks. I'm going to try turning it off and re-running the logs.