azmi951

I have a few Bosch wide band sensors but no display. Is there a CHEAP display out there or a converter to use a standard A/F gauge.

I have seen the DIY kits but cant find a place that sells the whole thing or a price list. I just want to make sure everything is good.

Ski

depends on which bosch 13246?? or something like that? Tech Edge WBO2 DIY.

Danno

I bought my TechEdge unit with Bosch LSU sensor for a total of less than $200 US. Datalogs multiple inputs as well as WBO2 voltage vs. RPM. Other units log WBO2 voltage vs. time, which is not of much use....

I used it to datalog WBO2 voltage compared to the stock flip-flop O2-sensor to check the 'accuracy' of my ARM1 display. NOT EVEN CLOSE! Well, the instructions with the air-fuel ratios of each LED was competely off, but turns out my testing worked. Found that my prefered target of both the last green & first blue LED both flickering on and off simultaneously corresponded to my target of 12.0:1. The manual probably means the air-fuel ratio at the center of the LED, but you have no idea how close the real mixture is to the left or right edge of an LED ready to flip to the next one. So that's why I like to read on the edge where both LEDs are hit. Then you know the voltage is fixed within a narrow range.

Monitoring a flip-flop stock O2-sensor would probably be best with a digital voltmeter anyway because you want to get down to 0.01v resolution. In which case, the stock O2-sensor works pretty well if you make sure to do 3 full-throttle runs and only take the reading off the 3rd run. In which case, 0.87-0.89v really does accurately show 12.0:1 air-fuel ratio.

What a messy procedure though... just get the TechEdge WB unit.

Jason_86_951

Hey Danno,
Check this little bugger out.
With some transparent colored tape over the diplay to indicate fuel ratio, this would be the cheapest, and most accurate O2 sensor gauge that we could do.
I'm going to order one and try it,
http://www.marteltesttools.com/produ...n=detail&id=67

Jason_86_951

double post

J Chen

Jason,
Check out Jaycar. It's an Australian electronic store.
Danno, are you using Techedge model 2AO wideband ?

ftanguay

anyone have ever try to built there own reader? like Jason_86_951 idea. It's just take a display and a little op circuits... about 20$ of pieces. What is the exact reading from the o2 sensor? 0-1V?

Jason_86_951

Yeah, 0-1vdc. That's why that little display would work perfect, I'm ordering one tomorrow and will report on how it goes.
I think with the parameters mapped out for what voltage=afm I could format something on the PC and then print it on a clear sticker............poof an acurate O2 display for under $30.
Granted it's not a wide band, but better than those stupid leds.

ftanguay

but you could do a simple OP device that convert the 0-1V to rear A/F ratio

Danno

The issue with using a simple voltage-comparator circuit to map the 0-1v range of the stock O2- sensor is that it's not linear, while the sweep of the needle is. You end up watching a narrow 1/4" sweep in the middle where it goes from too lean at 13.0:1 to too rich at 10.0:1. The only to unkink the S-shaped volrage-response curve on the standard O2-sensor is with a digital PLC microcontroller with pre-programmed table of voltage-to-afr. Then each segment of LED can represent a linear change in air-fuel ratio.

Jason_86_951

Danno,
Could you post this conversion table?

azmi951

Danno do you sell the tech edge kit?

Jason_86_951

I found this but the curve does not look quite right to me..Danno??

ftanguay

thats make sense wy they use led. It can be done using 3 comparator but have to use led as well or as you said Danno use a PLC. I tought of it a long time ago, put a 12V Koyo PLC in the car to monitor everything. With that it should be no problem to have a wide band with digital reading. Anybody have try it?

hally

tech edge wbo2