O2 reading seems wrong

[maddios]

Hi guys, I'm using an MSII v3 board currently running 2.673 7c code, and i'm having a weird problem.

It's currently running fuel only, piggyback on a BMW 1991 M5 motronic. And when i try to tune so the o2 sensor starts sweeping back and forth, the engine starts to run rough, especially at idle.

Also i guess i need to figure out how to use the blend AN/SD because i have low resolution on the MAP (76kpa idle). Anyone know how to use the Alpha N map? thanks

[78Spit1500Fed]

And when i try to tune so the o2 sensor starts sweeping back and forth, the engine starts to run rough, especially at idle.

I don't know of any engines that will idle well at stochiometric mixtures... typically idle speed is tuned rich on purpose, to avoid just this type of behavior.

Set your RPM above where you idle, then tune the bins in the VE table manually to get a smooth idle.

If you motor is running roughly at stochiometric at higher RPM's, I would suspect the ignition system to be at fault.

-Brian

[maddios]

Thanks

Is there a way to lower sensitivity on the VE values? while i'm revving it at say 2000, at 65kpa or so, the mixture is rich at 35, and it quickly goes lean at 33, however 34 seems to sway either way... how do i make it so my VE values are less sensitive, say add a multiplier of some sort to it.

Would messing with the ReqFuel thing allow me to shift the table?

Thanks

[cossie_storm]

Hi
I hade some problemt like that to.

If it is a problemt at idel, try to adusjt the ve tabel at the lover table

i just added a value like +10 at them, and that fixed it 4 me.

Good Luck

[maddios]

I'm sorry cossie, i'm not sure i understand what you mean? If i add +10 to the whole table in the table editor, won't that just shift the table numbers +10 and make my car run REALLY rich? or is there some sort of multiplier i'm missing.

Thanks

[bubble]

there was a thread recently which suggested altering the required fuel value to allow the use of larger VE values reducing the "sensitivity" of the lower ones to make fine tuning easier

[maddios]

ah, thanks that's what i thought.

Since it's a mathematical formula, i guess if i lower the reqfuel/2 then my VE values should be *2 right?

thanks

[bubble]

1) save your current settings

you could use the scale function of the table tool and scale the required fuel to suit or you could start fresh and play around with the generate table wizard using different req fuel to leave you with a similar pulse width on the injectors and larger VE values.

ps: alternating the use of scale and shift in the table tools will allow you to "flatten" or "raise" the VE table without altering each value individually.

eg scale table by 1.1 ..... adds 1 to a VE of 10 and adds 10 to a ve of 100
if you then shift the table by -1 ... VE of 11 becomes 10 and 110 becomes 109. (richens the higher values) etc

[maddios]

yeah i already did that, i set my reqfuel to 7.2 from 14.4, and scaled the ve table by 2

Now i just need to figure out how to use the alpha-n/SD blend, the window isn't documented yet lol. My map is way too sensitive, and sometimes since the ecu cracks open the idle valve, it sticks in the "out of idle" rich section right above idle, and the thing starts to run real rich. But it's not so bad so i'm not really worried, eventually i'll switch over to the MAF, car already has a BOSCH M5/911 maf.