sorry if this has been answered somewhere else, i do a lot of reading but dont think i have come across this.
how can i go about changing the closed loop afr from 14.7? im trying to lean it out a bit.
sorry if this has been answered somewhere else, i do a lot of reading but dont think i have come across this.
how can i go about changing the closed loop afr from 14.7? im trying to lean it out a bit.
You have to disable o2 and tune sd tables to go leaner than 14.7 at cruise
so is there really no way to make closed loop use less fuel in any way? i've seen a difference in l/100ks between a few tunes but didnt have a wideband on the car at the time so hard to say what was going on exactly.
does the closed loop bias have no effect on this?
I don't think that closed loop bias does anything, tried it a long while back.
I experimented with a couple of things. I connected up the O2 sensor with the narrowband output of the Innovate LC1. It did work but at times would get hung/confused and cause issues.
I have also just tuned it to run open loop (other than idle which you can't switch it off completely) and leaned it off in the base fuel lambda table. This works good. But running at 16:1 never produced a massive increase in economy but did help.
yeah fair enough. just wasn't sure how the l/100ks could be different when cruising at 100 in open loop between 2 tunes. all good
seeing as the pcm obviously knows it has to aim for 14.7:1 when in open loop using the o2 as a reference, is that value not something that is able to be added to a strategy?
just asking questions for curiosity sake...
can you reword your question. Don't get what you mean.
sorry lol.
if the pcm knows in closed loop it is aiming for 14.7:1 using the o2 as a reference, does that mean somewhere in the strategy there is a value of 14.7:1 (or similar ie. protocol etc) for closed loop?
basically, what in the pcm is used to get 14.7:1 when in closed loop
Will try to explain later. Need to get my head around it first.
Last edited by turbotrana; 06-26-2016 at 10:32 PM.
i did a heap of reading on this and it seems because the pcm uses 1 lambda for closed loop the only real way to change it is by changing the stoich value which is a hack way or change the closed loop bias, but someone that did this said it wasn't the correct process to go about it even though it did lean it out.
i would still think the pcm is being told that .4v = 1 lambda, so surely you could just change that value to 1.03 lambda or something?
probly the best way to go about it is to use a narrow band output on a programmable wideband so that 1 lambda is more like .35 or something. need to get another innovate wb!
Lambda 1 is lambda 1. You can't change that so changing the stoich will only throw your trims out.
yeah i remember reading that about the stoich value now, read a heap of shit so lost track of some stuff.
how is the pcm coded to understand that a specific range of volts is equal to rich or lean?
Get your tune spot on and then disable closed loop. I did that and not only can you lean the tune out but it just generally drives better as you instantly transition to the lambda that you want.Originally Posted by misk
Closed loop is only really needed for emissions, if you are idling at 14.5:1 or 15:1 you won't notice the difference in terms of smoothness, yes the emissions will be off but you won't care as you are probably running a high flow cat which almost certainly doesn't meet emissions anyway.
I'm sure there is a way to do what you want but imo it isn't worth the effort. I looked into narrowband simulation and stuff like that but didn't bother in the end. I think the O2 bias might do what you want, have you played with it much?
Also if you are running big injectors I find they tend to misfire if you lean it out beyond 15.8-16:1 so there isn't much fuel economy to be gained anyway. I tried running right on the misfire limit with extra timing and I couldn't barely even gain 1L/100km driving around town.
If you really want to improve economy and you do lots of short trips then nuke all the cat warmup timing. I did that and my car runs full timing when cold, not only does it drive much better but that gained me almost 3L/100km in economy.
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