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Short term trim with no oxygen sensor?
Posted: Wed Apr 14, 2021 8:41 am
by TurboTapin
I was making a few changes to my idle after installing a new catch can setup and noticed that with my oxygen sensor disconnected, my short term trim was well still trimming... is this normal? 1990 HCR32 RB20 ecu. Latest 1.1 firmware.
I had reset my trims and both short and long term clearly read 0 before beginning. My oxygen sensor reads .30 when it is unplugged.
Re: Short term trim with no oxygen sensor?
Posted: Mon Apr 19, 2021 9:44 am
by Matt
It shouldn't trim, but I have seen the STFT cycle sometimes at idle, but not affect injection time. If this is the case, then the trim is not actually doing anything. Generally I haven't seen trimming have an effect at idle
Re: Short term trim with no oxygen sensor?
Posted: Wed Jun 29, 2022 10:45 pm
by RomChip200
Matt wrote: ↑Mon Apr 19, 2021 9:44 am
Generally I haven't seen trimming have an effect at idle
What ?
Trim happens in idle and affect injection times.
LTFT is applied immediately and affects injection times, @idle, speed=0
STFT take a while to escape from the 100 value but they do after a while (>30secs) and affect injection times too.
When you exercise the throttle, a part of the STFT previously calculated will affect the LTFT.
On V6, this allows to balance the 2 engine banks and to have a smooth idle.