eratic o2 readings

cbx1147 · Post by **cbx1147** » Fri Jun 09, 2006 8:03 am

I have a 383 chevy with a fairly large cam (.510 int. and .520 ex.) and full length headers - port injection, alternating, 2 squirts -running a 3 wire NB o2 sensor in the collector. I get very eratic O2 readings all the time except at larger throttle openings and higher rpm's. Is this because of the o2 sensor distance from the head? Only sampling half the exhaust pulses (one bank of cyl.) and therefore uneven interval of exhaust pulses? Or am I doing something wrong?
Also would I benefit from say 4 squirts instead of 2 or rewiring the injectors so one bank feeds the first 4 cylinders in the firing order and the other bank of inj. feeding the next 4 cylinders?

qadir03 · Post by **qadir03** » Fri Jun 09, 2006 10:47 am

Are you looking at the AFR convertion that MS does or are you looking at the raw voltage? It is normal for the NB voltage to fluctuate a lot. It can only tell you if you are at stoich, rich or lean. It should read .8V+ when you are at WOT and when accelarating. Cruise it should jump around .3-.7V, this traslate to stoich. Anything below those voltages, it is lean. I hope this helps.

cbx1147 · Post by **cbx1147** » Mon Jun 12, 2006 11:53 am

Thanks,
I am looking at the o2 sensor voltage on the 8x8 fuel map tuning page. I am thinking I may have to go to a WB o2 sensor to get the results I want. Will a wide band sensor give more steady readings?

qadir03 · Post by **qadir03** » Mon Jun 12, 2006 4:31 pm

Yes, using a wideband will give you steady voltage reading. I've been using the innovate lc-1 for quite some time now. It will make your tuning experience much more plesant. In addition, you can use the AFR table to function as a closeloop and always have the correct afr mixture.