wideband o2 numbers

120 · #1 (**permalink**) 08-21-2003, 09:26 PM

hello again,
anyone have a range of numbers for a street /track motor?

My tuning is limited, so far I can get the 4k rpms at cruise around .99. The 4k rpms under load- no pump, around .90.
Waiting for some different idle jets for the progression. Which I believe should be around .95.

Should I be looking for .95 at 4k rpm light load? Would that be leaner mains, or emulsion tubes?
Is there a good number for idle, or is that to difficult for a carb?

Bruce
broke down for a wb o2 meter

turbolarespider · #2 (**permalink**) 08-22-2003, 08:38 PM

Anywhere around 1.0 for idle, light loads, cruising up to 80mph is fine. Assuming the engine is happy, and does not misfire (it shouldn't)

At WOT, considering you are using carbs, I would shoot for .8, although best power is about .82. Carbs are notorious for not being consistent...

Eric

120 · #3 (**permalink**) 08-23-2003, 04:47 PM

thanks Eric,

I've got a bit to go, .77 is my current idle

Bruce

67GTV · #4 (**permalink**) 08-24-2003, 02:59 AM

Are you guys speaking in secret code?

I have no idea what you're discussing.

turbolarespider · #5 (**permalink**) 08-24-2003, 01:29 PM

The numbers that are put out of good wideband O2 sensors are in inits of Lambda, which is actually unitless...

lambda = actual air fuel ratio/ stoich a/f.

For non Californa states, stoich is 14.6, CA is 14.3, Europe 14.5...

Anyway, .8 = 11.68:1 a/f ratio, .77 is 11.2. Which is pretty darn rich.

Max power is about 12-12.5-1, or .82-.85.

Make sense?

Eric

67GTV · #6 (**permalink**) 08-24-2003, 03:30 PM

Nope. It's over my head.

Is this something I should know for an older Alfa? Is a "wideband O2 sensor" a diagnostic tool?

120 · #7 (**permalink**) 08-24-2003, 04:57 PM

67 GTV,
I had a sensor boss welded to my car's exhaust pipe and got a simi inexpensive wide band o2 sensor meter.
All this does on a computerless car is allow me to read air fuel mixture while driving. Since I have just installed a modified 1400 motor in my giulietta I want to get all I can get out of it. Have to since it would have been much wiser (power wise) to put in a 1750, or even a 1600.

A less expensive route would be a regular o2 sensor hooked to a mixture meter. I had one of those and it really worked pretty well. With the wide band sensor I can determine the exact richness condition of the exhaust in the tail pipe. As you can see from Eric's post there is a figure that you can strive to tune to.

Someone with better experience than I would prolly tune near enough to the ideal without the meter. If I had solved my weber riddle sooner I wouldn't have bothered with the wb o2 meter.

Bruce

67GTV · #8 (**permalink**) 08-24-2003, 09:32 PM

Thanks for clearing that up for me Bruce! I knew I did not have an o2 sensor on my GTV. Replaced one on my old Honda. That's about as far as my knowledge of them goes.

75evo · #9 (**permalink**) 10-09-2003, 02:08 AM

Hi,

I have wideband setup (Autronic Model A with a Bosch LSM-11 sensor). My car is tuned to run at 0.878 Lambda (or about 12.9:1) at 100 Kpa (full load) at WOT.

At light loads and low rpm, I advanced the ignition and lean out the mixture (15:1).