AFR in Closed Loop

[Kodename47]

I've always put it down to the lack of input into the rear O2, so only fixed with custom maps for cruising AFRs. It will still do this when dropping out of the custom map parameters though.

[504]

Originally Posted by Kodename47

I've always put it down to the lack of input into the rear O2, so only fixed with custom maps for cruising AFRs. It will still do this when dropping out of the custom map parameters though.

Makes sense, only really started happening under E5 ethanol reading, I wonder if a min voltage could be applied to maintain a minimum E reading to avoid such issue?

[tomm.brz]

it can't be lack of o2 sensor, at least phisically, because i always had that even with rear o2 plugged in, but disabled in tune

[504]

may have resolved this fellas but no way to test until I visit my tuner again, basically need to be certain before I do that

see attachment below, set BOTH these tables to ZERO to remove all impact rear o2 may have on closed loop fuelling. Essentially, with flex fuel tuning, the Rear o2 will read a very low voltage on E0, and this appears to trigger a rich response

If anyone having similar issue could test this and provide feedback here, that would be greatly appreciated @!

[tomm.brz]

we already did that, it s a normal thing to do when you remove rear sensor, it doesnt fix the 13.8ish afr when you return to throttle

[504]

Originally Posted by tomm.brz

we already did that, it s a normal thing to do when you remove rear sensor, it doesnt fix the 13.8ish afr when you return to throttle

so is there really zero solution at all to this issue?

really dont want to be running 10% rich now that eflex is not available .....

in that instance, how about forcing a minimum voltage through the flex sensor to the point the issue is alleviated?

Edit: your last comment is contrary to your earlier mention of no rich issue without rear o2?

[steve99]

Originally Posted by 504

so is there really zero solution at all to this issue?

really dont want to be running 10% rich now that eflex is not available .....

in that instance, how about forcing a minimum voltage through the flex sensor to the point the issue is alleviated?

I have rear 02 connect flex kit with AF#3 correctins zeroed, fueling is fine on petrol and e85.


Check fhe ethabol sensor scaling and fueling​ compensation tables. I also keep ltft active in open loop.


Is your fuelong problem in open loop only

[504]

Originally Posted by steve99

I have rear 02 connect flex kit with AF#3 correctins zeroed, fueling is fine on petrol and e85.


Check fhe ethabol sensor scaling and fueling​ compensation tables. I also keep ltft active in open loop.


Is your fuelong problem in open loop only

I dont have tune access, but am very confident fuel comp tables are dead zero (i.e. stoich) at everything below 0.6 load. perhaps an issue of setting 0.000 rather than -0.029? seems unlikely

I cant check fuel status but both STFT and LTFT is active so seems closed loop. Effectively after every shift it commands 13.8, then after 30 seconds commands 14.1, then 10 seconds later 14.3, 14.5 and if no shift, 14.7. if shifted, it goes back to 13.8 strictly and process repeats. this happens under very light load, fuel economy style driving

I have been running e70 for basically the life of the car and hadnt tested 98 till recent. 14.7 commanded was a non issue till flex sensor started reading below e10 so kind of pinned it down to rear o2 sensor voltage.

Those two tables I pictured above seem to be the culprit, I do only have one shot to get it right though with tuner being so far

[tomm.brz]

Originally Posted by steve99

I have rear 02 connect flex kit with AF#3 correctins zeroed, fueling is fine on petrol and e85.


Check fhe ethabol sensor scaling and fueling​ compensation tables. I also keep ltft active in open loop.


Is your fuelong problem in open loop only

Steve i think it s just the problem that kodename noticed time ago, during closed loop when you go back to throttle.. i always notice it when Rear o2 is disabled in tune and noticed the most on 2015-2016 euro cars with F10G rom
with my K00G i notice too but less often and for shorter time

[steve99]

Originally Posted by tomm.brz

Steve i think it s just the problem that kodename noticed time ago, during closed loop when you go back to throttle.. i always notice it when Rear o2 is disabled in tune and noticed the most on 2015-2016 euro cars with F10G rom
with my K00G i notice too but less often and for shorter time

So your saying if i cruise along on closed loop then accelerate i will get rich afr of 13 for quite aome time, is tgis in closed or open loop the rich running ?, I do quite a bit of logging on highways cannpt say ive noticed this

[tomm.brz]

I thought kodename showed you many times this behavior,
for example i'm tuning a F10G brz, that has rear 02 disabled:


https://datazap.me/u/tommbrz/boxer-v...-4-5-15&solo=2


look at Afr target
it's actually 14.7 both in open loop fuel target table and closed loop target but it's targeting 13.82 when on throttle and closed loop



f10g calibrations are the worst, at least in my experience, d00g a bit better, a02g much better and just do this sometimes, and for shorter time
k00g also do it sometimes, not often


never understood what triggers this and how to fix

kodename fixed it forcing open loop all the time, and he created a custom closed loop fuel control with custom maps,

i just keep it like that and force-lean offsetting lambda sensor scaling to have a leaner real afr, but i also have a wideband sensor always plugged in

[Kodename47]

Originally Posted by steve99

So your saying if i cruise along on closed loop then accelerate i will get rich afr of 13 for quite aome time, is tgis in closed or open loop the rich running ?, I do quite a bit of logging on highways cannpt say ive noticed this

Yellow is CL target
Red is AFR

[tomm.brz]

... that stupid 13.82 afr... i gave up trying understand it, think is some undefined tables/logic acting this way

which calid do u use kodename?

[504]

Its very interesting that this issue is resolved with subaru wrx's through the above tables, but potentially not with 32bit ECUs?

We do know that a low voltage reading to the rear o2 will tell the car its supposedly in a lean condition, therefore adding a dummy 0.3v minimum input may resolve the issue entirely. Not sure how to go about doing that