Need Help With Air/Fuel Ratio Gauge Install...

[TransforminLegacy]

I was wondering if anyone could tell me exactly where the o2 sensor is on a 95 Subaru Legacy..I'm tryin to install a air/fuel ratio gauge and I have searched almost every website for a diagram of exactly where the o2 sensor is so I can connect to it for a reading off my gauge..if anyone has info please feel free to respond..

[MDLP412]

i dont think 95's have o2 sensors....

[Sarra]

Seriously? It's in the exhaust... Just trace the wiring to find where to hack up the wiring and mess up the ECU.

Your best bet is to get a dedicated wideband and weld in another bung, and run the wideband separate from the car's narrowband. The Narrowband is horribly inaccurate.

Also, OBDI required an O2 sensor, so it has one, but probably only has one, depending on the state it was sold in originally.

[Huffer]

i dont think 95's have o2 sensors....

you HAVE to be joking...

The 95 legacy has an o2 sensor right behind the header and then one more after the two catalytic convertor. In order to wire in the wideband o2 you may just want to weld in an additional bung.

[StatGSR]

^ i doubt he is going wideband, and if he was he would have to weld in an additional bung and have completely separate wiring.

im sure its just one of those worthless little fancy flashing lights AFR gauge. and if that is the case my advise is to return or sell it.

[TransforminLegacy]

no actually i bought a wideband but I need to find out where to put another reader at..thanks for the help

[Sarra]

The wideband uses a totally different sensor than the factory O2 sensors.

Wideband O2 uses 7 wires, a factory heated O2 sensor uses 4 or 5 wires. An unheated O2 can either have 1 or 2 wires. You aren't gonna get a Wideband signal over just 4 wires (one of the 5 wires on the 5 wire O2 sensors is quite simply a redundant ground wire).

Also, if you put a wideband in where the factory front O2 sensor is, you may end up burning the poor sensor up. The best place to put it would be right before the first cat, or near the muffler, cooler exhaust is better (Widebands have really nifty heaters in them).

[StatGSR]

^ u want it before the first cat, not by the muffler, thats to far down the exhaust stream imo.

[grayguy]

Depending on which wideband he has, he might be able to put it in the factory spot and use it to send a narrow band signal to the ECU. That's how my zeitronix is setup. Also, My Wide want is installed about 8inches behind the turbo (less than Ideal I know) and hasn't burned up in the past 9 months.

[Sarra]

^ u want it before the first cat, not by the muffler, thats to far down the exhaust stream imo.

Well... If it's an LC-1 or LM-1, they make tailpipe adapters for them. The Wideband can accurately read afr from the tailpipe, even through the cat. There's a sophisticated heater element in the wideband sensor itself, so even at the very exhaust tip, it will always be in operating temp. Putting it in the manifold is actually BAD for the sensor, because excess heat WILL eventually kill the sensor. Widebands are sensitive to heat, unlike narrowbands. With a narrowband, as long as it's over 600F, it's happy. Widebands like to be in a certain heat range, and a manifold would get higher than that range on most cars.

Putting it right before the first cat would, IMO, be the best solution. other than that, right before the muffler would be the safest option for the sensor itself, though there will be a slight lag due to any cats in the system. They do read accurate at the muffler tip though, I can verify that from my own experience. ;)

[Sarra]

Depending on which wideband he has, he might be able to put it in the factory spot and use it to send a narrow band signal to the ECU. That's how my zeitronix is setup. Also, My Wide want is installed about 8inches behind the turbo (less than Ideal I know) and hasn't burned up in the past 9 months.

Hate to rain on your parade, but so far, I have yet to see a single wideband that doesn't use a Bosch sensor. The controller might be different, but Bosch currently makes the only Wideband sensor. ;) Once that changes, maybe we'll have widebands that like the heat a manifold produces.

Now, on the older NA's, with the first O2 basically right before the first cat, that's probably the best place for a Wideband anyway. If you put it in a runner, the damn thing would melt. I'm not actually sure about the newer ones. On a turbo car, for sure, put it in the downpipe, before the first cat, or where the second O2 would go if catless.

[anothernord]

My wideband sensor is mounted to a bung that is at the very end of the Borla headers, right before the flange to the cats. I have a coupler copper fins and a spacer to keep it from getting too hot and getting to much flow respectively. Oh, and I have the Innovate LC-1 with the Bosch sensor.

[Sarra]

how often do you calibrate it? Just curious, since I've heard of it requiring to be calibrated frequently. :p

[anothernord]

how often do you calibrate it? Just curious, since I've heard of it requiring to be calibrated frequently. :p

I do a free-air calibration every couple months. It doesn't lose its calibration very much though.

[Sarra]

how often do you calibrate it? Just curious, since I've heard of it requiring to be calibrated frequently. :p

I do a free-air calibration every couple months. It doesn't lose its calibration very much though.

That's what I thought. Very nice.