in the FSM it mentions briefly about hooking up an "o2 light" that goes on when rich, flashed when stoch, and goes off when lean. how does one hook this up? and where? what do in need to do it?

 

Just hook the positive meter lead to the O2 sensor pin on the ECU (if you have the FSM, it's on page 4A-30 or so, on the S4's, anyway), and put the negative meter lead to ground...Start the car, and check it out...When the ECU is running in "closed loop", you should get a perfect A/F ratio with the meter bouncing back & forth between .4 and .5 volts (this is where an analog meter comes in handy, instead of a digital one, which won't be able to keep up with the fluctuations)...All other ratios will either be above, or below .4 to .5 volts, but everything should be between 0 and 1 volt...

 

I do believe I'll be trying this later tonight. I found all sorts of interesting looking readouts from the ECU that I can monitor! Thanks for the info, Wayne!

How does one read the stuff without disconnecting the harness?

-=Russ=-

 

i dont remember where, but i was trying to find out if anyone knows.. in the FSM it mentioned somewhere about there being a wire harness plug that you could hook up a test light to, that could function as a simple o2 meter, with the light blinking at stock, going off at rich, and going on at lean or something like that. oh well ill prolly end up doing the DIY a/f guage anyways.

 

Yes, it's called an A/F gauge...You can do the same thing with your meter, unless you really like watching the pretty little lights...

Russ- the meter probe goes into contact with the back of the pin in the ECU plug, no disconnecting needed (kinda make the car hard to run to take the measurements, wouldn't you think? )...A little piece of wire, or maybe a paper clip instead of the meter probe helps a lot, as do radio shack "jumpers" with clips on the ends to connect the leads to the wire/ clip/ etc...

 

Aah. Ok. That's sort of what I was thinking. Thanks!

FWIW, I'm planning to build my own A/F meter out of a LM3914 decoder or two. I like blinkenlights!

-=Russ=-