In case you buy one of these Air/Fuel Ratio gauges and see that the documentation they give you really sucks. Here is how you hook it up for a Scion xB.

Typical legal stuff...Perform this at you own risk, I will not be held responsble for screw ups. This is just info I gathered before I actaully installed the gauge.

You are going to want to connect just after the connector where the O2 sensor meets the factory wiring. The O2 sensor signal high side wire, which is Black, is shielded so don't connect to the O2 wiring. I found just after the connector is best place to splice in. You can verify the 4 wire O2 sensor Black signal wire at this Link:

http://www.cats-direct-shop.co.uk/la...ing-advice.php

You may want to use some shielded wire to the gauge, I didn't and it's working fine. The gauge will be all bouncing back and forth between rich and lean. This is normal. The computer is constantly adjusting the air/fuel ratio. The key is, if the indication becomes sluggish or constant rich or lean, this indicates a problem. The oxygen sensor is probably fouled and should be cleaned or replaced.

 

Actually, the reason it fluctuates so much is because the gauge that you have is a "narrowband" air/fuel gauge. It cant compute fast enough to have a stable a/f. No a/f should fluctuate that much. Those gauges are only accurate at WOT (wide open throttle). To get any sort of accuracy, you need to go to a wideband style setup that uses a dedicated o2 sensor. When you do this, you will see what I mean. You will get a far more accurate reading...

 

Thank you... I really appreciate the information. Seriously, you guys are awesome.

 

Exactly true.. mine looks like a mini windshield wiper (needle style gauge) when at any throttle, but WOT. At WOT it then settles.. usually a little on the rich side, but I really do not count that either... not until I go wide band

 

Well, first of all, the black wire isn't the right one to hook into, I got no reading at all, it was disappointing. SO... I tapped into the blue wire which gave me readings.
UNFORTUNATELY... my gauge is stable :-/ When I am stopping or coasting it rolls to LEAN, and when accellerating, it stays at RICH and at normal driving it is STOICH./RICH... So, I must have a little bit of a problem going on.

Help anyone? (I'm not throwing any CEL's)

 

for me, on an 06, it was funny.. I started with the black wire/s and got nothing, I then found a wire that is doing what
you describe^ I ran like that for a week, then realized it wasnt right, I then re tried the black wire.. and it worked
perfectly since.. I then realized it doesnt read until it is at full temp, (low temp light off) and the o2 is heated.

you dont have an issue.. dont let the gauge be the deciding factor. It WILL take a wideband set up for the reading to be true.

 

Alright... I'll take it apart again later. It's weird that I never had any problem like this on any of my other vehicles, though. I know it's different... but I also work at a toyota dealership and am going to have them look at my car soon...

 

ya.. its part of that low temp, start up, system.. it runs in closed loop until the O2 is heated... it seems to be cutting
that signal, until it is up to temp.. not sure, but I do know mine doesnt really read until hot.. Good Luck!

 

Does it give you a around the corner reading of what you are running like lean or rich because i was going to put one in because i started my car and i reved it because my friends were standing there and they said i blow out a little black smoke and no i am not buring oil i only have 28,000 miles LOL!!!!!

 

it'll blow a lil black smoke when its cold cause its running rich when its cold...

 

^^yeah..

and the reading is only true (maybe) at wide open throttle (using the OEM sensor)..
wideband FTW

 

one other question do i hook it up to the o2 senser in front of cat or the one behind the cat

 

Thanks for the heads up

 

In front of the cat.. you want a reading before the cat does its thang!!

 

lol kool thanks and dang the one after the cat wires come in where the shifter is lol would be easy now i have to find out where the one before the cat comes into the cab lol and last thing i know i am asking a lot but i want to get it right the first time lol which wire do i hook it to the signal wire or to one of the heater wires. i know it is a no brainer but i want to just make sure LOL!!!!

 

I ran a wire out of the rubber plug, on the firewall, behind the brake booster.. you can get down on the driver floor board and look up, you can poke it out through there easily.

Then you can tap the O2 wire, where it meets the connector, in front of the firewall, on the sub frame.. I would tap on the sensor side of the connector so no mishaps happen with your wire harness..

ok, as far as which wire.. lets see if I can describe it.. on my 06 there are two black wires.. only one is the signal.. where that connector is on the sub frame, looking at it from the front of the vehicle, it is the top right wire of the four wire connector... The wire colors change from the sensor side to the harness side.. the two blacks are on the sensor side.

I was able to hide my wiring completley hooking it up like that.

 

LOL... ready for this??...

 

thanks for the paper drawling LOL!!! I was just out there messing with my car trying to hook it up and got it and it is running from ideal and rich in between those lol that is good and at full throttle it runs more towards the rich but it is ok thats what it is suppose to run lol.

 

yeah.. thats it.. at wide open throttle it sits just beyond the rich line.. which isn't bad..

 

I just noticed that i hook it up to the o2 behind the cat LOL i have to hook it up to the one in the front LOL but i am wondering my friend said that i need to have to have a wideband hooked up to so it will be right and not just a light show but i dont know not to many people know about the gauges and if they really work or it is just a light show !!!! LOL!!!