View Full Version : Done with cheap AF gauge
I've completed the cheap AF gauge for my 20VT Ibiza.
I got a 2001 AYP engine and it turned out that it has got narrowband lambda sensors (both before and after cat), so a cheap gague works. I guess all pre 2001 1.8T engines got narrowband sensors, so most of us can use a gauge like this.
It has got ten LEDs, 3 lean, 4 stoich and 3 rich. Usually it is jumping between led 1 and led 7 (very lean and slightly rich) all other leds seem to be useless, but when flooring the upper 3 leds slowly get illuminated. Really interesting :). You cannot really determine how rich it is, but you see that it is everything OK at least.
If anyone is interested i can make a complete writeup.
You make the gauge yourself?
WOuld be interested in a schematic if one is going....
JAmes
slim_boy_fat
26-03-2004, 07:41
I've completed the cheap AF gauge for my 20VT Ibiza.
I got a 2001 AYP engine and it turned out that it has got narrowband lambda sensors (both before and after cat), so a cheap gague works. I guess all pre 2001 1.8T engines got narrowband sensors, so most of us can use a gauge like this.
It has got ten LEDs, 3 lean, 4 stoich and 3 rich. Usually it is jumping between led 1 and led 7 (very lean and slightly rich) all other leds seem to be useless, but when flooring the upper 3 leds slowly get illuminated. Really interesting :). You cannot really determine how rich it is, but you see that it is everything OK at least.
If anyone is interested i can make a complete writeup.
Jumping about is standard for a narrow band A/F gauge. Its really only any use on full throttle, where you hope its in he green.... :blink:
Yes, i'm making the gauge myslef. I'm about to do some more, as my friends over here requested some pieces :). Schematic and writeup will be available soon.
The ECU is trying to keep the A/F every time stoich, except on full throttle. I have simplyfied on the design: 1 (red) LED for lean, 1 (yellow) for stoich and 3 (green) for rich. I have calibrated the voltage range, so the "gauge" shows red/yellow when cruising, and illuminates the second green (rich) LED on full throttle. Actually the third green LED does not light up now, as it means a too rich condition, it just illuminates for just a moment when shifting gears. It's not that PRO, but very very cheap and works.
This is how the finished product looks like (sorry for bad pic)
Alright mate? Its looking good to me, why you get rid of the lower down LED's? just so that they would stop flashing when your driving about? i suppose you really only need the one as your using the stock O2 sensor.
Still looking forward to that schematic if its still going
CHeers
JAmes
The first two leds (red/yellow) show a lean/stoich condition. They are just flashing while cruising (when no full throttle). Then the last 3 green LEDs show the rich condition, first one should be around slightly rich, second rich and third very rich. When flooring my car begins with the first green led, then first and second together (just like on the pic), then second only. The third one does not come on, except for a short moment when shifing gears. Writeup comes