2000SSNB

iTrader: (4)

I am not sure how the AFR of 14.7 is actually regulated at light throttle?
Looking at the O2 sensor signals they are fluctuating a lot (not averaged).
Does the PCM take the o2 signals (rear, towards exhaust) and average them out internally and relate that signal to an internal reference (450mV or so??? equal
14.7)?

Thanks,

Gert

patSS/00

iTrader: (6)

Yes, the signals are supposed to fluctuate rapidly - the PCM figures an average value for the front ones to determine afr, the rear ones are used to make sure the cats are working.

2000SSNB

iTrader: (4)

As i am hoping for EFILIve 7 plus flashscan to come out soon,
I am wondering if the commanded A/F ratio at cruise etc.
can be directly modified in the eraseable PROM?

Gert

HumpinSS

iTrader: (1)

Not in closed loop. Open loop yes but closed loop no

wait4me

iTrader: (10)

on ls1edit you can change the closed loop desired ratio just by putting what you want on the box, and as for the open loop f-a you can adjust either ve table, openloop f/a table, or pe vs rpm table, or numerous other tables to get the same effect.. closed loop is computer controlled, open loop is just a predetermind calculation set in a non changing table.

HumpinSS

iTrader: (1)

If the stock sensors are still being used they are very inaccurate at any ratio besides 14.7

wait4me

iTrader: (10)

ok humpinss, here is the deal, yes the o2s are very accurate at 14.7 and nothing more, that is why the pcm does not use closed loop durring wot, "closed loop is fuel ratio controlled by feedback from o2s ect to maintain a desired af"... The way it fixes everything, is thru the ve table, with fuel cell changes by ltrims and strims. Since the computer knows it can set all the whole table to 14.7 then it assumes that the wot fuel will always be correct, thats why we will see a positive number sometimes when we enter power enrichment. that is the computer adding that amount of fuel to make it a 14.7 then added the power enrichment calculation, to equal the 12.8 or so fuel ratio. It is all really easy, just people seem to make this alot more complicated and go to far into it.... jes

2000SSNB

iTrader: (4)

Thanks for the feedback. So the answer is that it is possible to change comanded A/F for light load in closed loop (for ex. 14.5) but that the actual
measured A/F may be much lower(for ex. 14.1) because of the larger
error of the sensor at lower A/F ratios.

Thanks for the feedback,

Gert

samz28

i'd like to know how to tighten up the sweep. Instead of reaching rich/lean in a large sine wave, i'd like it to be a very tight or non existant(not likely) sweep.

Question is how will the map changes be affected by limiting its ability to move trims around fast? could be a catch-22

wait4me

iTrader: (10)

sam, have you just tried setting your whole table up to 500 mv on your o2s via the ve table? when you do that the o2s barely move when it is in closed loop. force the car into open loop, then try to hit all the cells you can and just do lots of logging, then you just add or subtract each till you are done, it dont take very long to get it right, then when you plug everything back in and get the car back into closed loop, it will have all 0 ltrims and maybe a 1 or 2 strim every once in a while. and the o2s will not sweep so far apart.

wait4me

iTrader: (10)

or i guess if you dont want them to sweep, you could just leave the car in open loop all the time.