A/F gauge questions - NEED HELP!!!

mweinst · 06-09-2001, 05:31 PM

Ok, I've got a new Autometer A/F gauge installed but it doesn't seem to be working. This is an Autometer gauge, but it has 10 LEDs like the Huntley model.

When the car is warm, it seems to dither, but only 5 LED's light up (from lean to stoich). Even at full throttle and full boost, it only lights up 6 LED's (from lean to 1 richer than stoich).

I have a 3.0 bar FPR and a new O2 sensor, so I would think that I would be lighting up at least 8 of the LEDs at full throttle/boost. I want to install my new adjustable FPR, but think that I should get it the gauge to work correctly first. Is it possible that I am just not really running rich?

HELP - Autocross in the morning!!!

wolfrpi · 06-09-2001, 07:20 PM

Test the voltage going to the unit - should be .8-1.o volt under full boost. If this is the case, you're ground is bad on the A/F because the last lights should be illuminating (.1 volt for each "bulb" on the A/F). If not, you might have cooked the 02 sensor on install, I know cause I did the same thing on my 951..lol. It's easy to twist and ruin the wires to the sensor because of its placement.

Erick

kcturbo · 06-09-2001, 08:16 PM

Im gona do the same with mine here in a couple of weeks, let me know how it goes. Have you made any adjustments to your A/F ratio yet? Where did you hook it up at?

Ehab · 06-10-2001, 08:23 PM

Well the signal from the O2 sensor doesn't really sit at any value continuously, when cold, it should be around .45, then when the O2 sensor warms up and starts really reading the mixture, it starts to oscillate with every puff of exhaust between .2 and .8 for proper mixture. Running leaner or richer will modify the whole range, but I don't see how those meters give you a stable number out of the oscillating voltage except by averaging over time, which means that even when you give it full throttle, the range might go to .3 to .9, which implies that the average shown on the meter will only increase from .5 to .6 .... which on your meter, makes sense.

Let me know if you think otherwise.
BTW, the O2 output is 1 volt max, and if it operating properly, it will oscillate, and will therefore rarely give you an 'average' reading of more than .6 or .7 ...

The best solution is to actually watch the voltage with a digital voltmeter, like I did for a while until I was sure the signals were okay and the car was tuned correctly.

Good luck.