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I'm trying to get my stock fuel trims to jive with my wide band tune. I'd like to change the airflow modes to jive with their intended boundries (idle, decel, cruise, wtc.) but I'm not sure if there are any or they are just arbitrary? If they are arbitrary I can just assign each number (0,8,16,24,32,etc) to my associated driving types which should make my fuel trims correspond to these regions, but I don't want to mess anything up.
What is your AFR error% showing when in closed loop? If it's +/- 3% you're as good as it gets.
I personally like to force them to values that match the 0,2,4,6,8,10,12,14,16 in the o2 switchpoints tables
then you can make a histogram for the o2 swicthpoints...use dynamic cylinder air as the x axis PID.. match up the values that correspond with the o2 switchpoint zones...and do a double check...ata minimum you will be able to use AFR error to get swicthpoint closer to matching...
really they dont do much good..you have to push it quite a ways away for it to jive nicely...and then its not near as acurate...
your best bet would be to buy a wideband and simulate narrowbands and use them...
get an LC1 cause its cheap easy and programmable, and you can then set your 02 switchpoints all to 450mv and it will be correct...
Only problem is there are limits that we don't have direct access to on the o2 switchpoints. So you could be making changes that you will never see as the values will be limited by constants in the calibration.
Scott, when you say you force 'them' to the values that are in the switchpoint table do you shift the numbers in the mass airflow VS: mode table around to match certain driving conditions (IE: 0 is decel, 8 is idle, 16 is cruise, etc) or do you just change any value in the mass airflow VS: mode table to match the closest number that shows up in the switchpoint table? I have it in my head that these airflow modes should correspond to actual airflow models like decel, idle, cruise, etc. I may be over thinking it. What I realized after messign with the switchpoints for a while is that what the narrowband O2 thinks is stoich doesn't change when you change the switchpoints, it just changes the fuel trims. So my closed loop AFR always seems to float around 15.5:1 regardless of where my switchpoints are, although I have not changed them that much.Quote:
Originally Posted by soundengineer
from what I can tell they are not modes like decel, idle,WOT...though in general it would be lower #'s for lower airflowsQuote:
Originally Posted by 5_Liter_Eater
I just make them so they are an single digit instead of halfway inbetween like some of them are..and I make sure they land exactly on the vales in teh o2 swicthpoint table...
otherwire you really cant set up a histogram to play with...well..you can...but its dam hard to tune something thats using a blend of 2 values..
stoich is alwys what the PCM label for stoich is...the o2 switchpoint value is supposed to be what stoich is at that particular airflow mode..
so if its XXXmv..then thats supposed to represent teh value in yoru Stoich AFR table
I couldn't find a way to have a histogram plot AFR error or fuel trims against the switchpoint table so I was plotting it against the mass airflow VS mode table but like you said, without the mode number jiving with a particular number on the switchpoint table it was not cut and dry.
I've set mine to the following to get a bit more resolution. We'll see how it goes.
I know stoich is defined by the PCM but even though mine is 14.68 it gravitates towards 15.5. Editing the switchpoints decreases the fuel trims but it still wants to be at ~15.5:1 even though I'm commanding 14.68:1.