Barwick

I just got my Air/Fuel gauge installed, with the 4-wire O2 sensor that comes with it, and I start the car up, it sits at 1 bar (lean), then maybe 30 seconds later it goes up to 2 bars (still lean), then 20 secnods 3 bars, then 20 seconds 4 bars.. etc.. etc.. all the up to full rich.

It doesn't fluctuate, nothing.. even under boost ('90 TurboII). I get crappy crappy gas mileage, and I'm wondering if this is the reason (hmm..)

The stock O2 sensor is a shielded wire, but the bright boy who owned it before me decided to cut that wire, and the shielding is no longer existant on either the O2 sensor or the wiring harness (just a single wire)

Am I to assume that this sucker isn't grounded correctly (I was told that's what the shielding does) and therefore the fact that I was getting the Check Engine light coming on, and the code reading "O2 sensor" (stopped doing it recently without me ever "fixing" it though).. could that be the reason, and maybe my car is just in default "full rich" mode?

What are the chances it's the O2 sensor (if it's not grounded right)? And if so, can I use the 4-wire O2 sensor and splice into the signal for that, and just send that to the ECU? Or do they send different voltages?

Other than that, what else could cause it? Although right now I'm REALLY focusing on the problem being the O2 sensor.

Barwick

oh yeah, and when I first ran the sucker, and pulled the plugs, they were the "good" brown color, light brownish, I guess that means not rich, not lean, correct?

I dunno.. that was a long time ago though.

SonicRaT

iTrader: (6)

on my 89 GXLII (Turbo2 engine/drivetrain/ecu) and a single wire o2 sensor, I read about 4 bars into rich at idle, at 6.5Krpm it reads a few bars below the stoich area, then of course when I let off it goes full lean. It's typical for the warm-up to slowly creep up however. Mine's just a cheap replacement O2 sensor from napa

Barwick

yeah but at this point I have 2 O2 sensors in my ghetto custom exhaust pipe. One is stock, the other is 4-wire.

Can I use this 4-wire one's signal in place of the stock one's signal?

SonicRaT

iTrader: (6)

That I'm not sure on, I think the 4 wire ones were heated so they didn't have to be warmed up (thus the extra wires) but I'm not positive on that. Where's Reted when you need him?

nd4spd

The 4 wire units are heated and take a minute or so to heat up. You can tell if it works when you cruise at steady state throttle. If the meter bounces around the center area, your going into closed loop. If it is always green, check to make sure it is hooked up right. You can use the same signal wire for the ECU and the meter. One wire is power, one is ground and I believe you ground the last wire but I will check tonight to be sure.

Barwick

there's 4 wires:
White - Power
White - Ground (yeah it seems wierd)
Gray - Ground to engine
Black - Signal

Now when I turn it to "on" it goes right to rich. I gotta doublecheck everything.. this is messed up.

DaleClark

iTrader: (55)

First off, what AF gauge did you get?

Next, the lights sound somewhat normal - as the sensor warms up, it will slowly build up to a reading. If the ECU isn't seeing the factory O2 sensor, the ECU won't go into closed loop.

The wire from the stock O2 sensor to the plug isn't shielded - I think the shield starts at or near the plug in the wiring harness. Actually, I take that back - the shield starts where the O2 sensor wire comes into the wiring harness. Yes, I've disassembled a stock wiring harness....

Dale

Barwick

but what about when it goes immediately to full rich now, when I just start it right up? Even when I just turn the key to "on", and it doesn't fluctuate at all?

I dunno, this thing is screwey.

DaleClark

iTrader: (55)

Again, what brand O2 gauge is it? Where did you get it from?

Dale

Barwick

I forget what brand, I got it off JC Whitney, same with teh O2 sensor

Barwick

bump

Barwick

laaaaaaaaast bump (unless I decide to bump it again)

Piranha

Hey Bar, you shoulda came out on Saturday to hang out! Get what brands you got, that makes a difference. And full rich is better than full lean

I would check your wiring.. make sure you have all the wires set up, A/F meters are pretty easy.