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Fluctuating idle with o2 sensor

Posted: Mon Feb 10, 2020 2:06 pm
by tomkun
Hey guys so just starting to learn how to tune my own map for my s14 rb25det s1 and I'm a bit confused at the moment. I unplugged my o2 sensor and adjusted my fuel map and after taking a log everything looks good in my opinion. I was able to get my idle just around 14.7 and wot around 11.5. Now when I plug the o2 sensor back in my idle will sometimes drop back down to high 12s through mid 13s. How can i get my idle back to a stable 14.7 without it creeping back down to the 12-13s. Did I do something wrong with my tune, is it possible that my o2 sensor need to be replaced? Also can I just drive with the o2 sensor disconnected forever or does it need to be plugged in,

Re: Fluctuating idle with o2 sensor

Posted: Mon Feb 17, 2020 9:13 am
by Matt
Now when I plug the o2 sensor back in my idle will sometimes drop back down to high 12s through mid 13s. How can i get my idle back to a stable 14.7 without it creeping back down to the 12-13s
Start looking at the trims at cruise. So take it out for a run when warm and see where the trims are around 2000rpm light load. They should be near 0% when your mixtures are 14.7:1

If they are not then you need to adjust your K/TIM until they are and then idle AFRs should be better

Re: Fluctuating idle with o2 sensor

Posted: Tue Feb 18, 2020 11:12 am
by tomkun
Start looking at the trims at cruise. So take it out for a run when warm and see where the trims are around 2000rpm light load. They should be near 0% when your mixtures are 14.7:1

If they are not then you need to adjust your K/TIM until they are and then idle AFRs should be better
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Would I adjust the kconstant if I have the FP and can use TIM?

I using a map my tuner sent me, its pretty much an off the shelf map he adjusted for the mods I have. I tried fine tuning the AFR by adjusting the cells the fuel map. Should I've adjusted the TIM first, then latency, followed by the fuel map?

Re: Fluctuating idle with o2 sensor

Posted: Thu Feb 20, 2020 10:04 am
by Matt
Start with reading our mapping guides. Otherwise I'm just repeating everything. Yes if you have TIM then use that to set your base mixtures instead of adjusting fuel map/latency first