Thread: O2 Wiring Dilema?

Hey guys, I've been running my T28 setup for a little while now, and I've been watching my narrowband AFR gauge (I know, I'm just broke right now...) and have been wondering about it's readings. When I wired it up I followed this thread over at Roasted Pavement to wire-up the O2 sensor. I am using the skinny O2 sensor as that was what I was told to use with the U13 ECU.

The reason I think something is wrong is from what I've read a narrowband oxygen sensor should read between 0-1v. And I read that 14.7:1 is somewhere close to .5v. Well my gauge just constantly reads rich (it is oscillating correctly, there is just never anything in between). Monitoring it on Consult shows it oscillates and reads back and forth from 0-1.14v. I am beginning to think that I have something wired up incorrectly.

I have a U13 bluebird ECU with a Calum Basic in my '93 NX2000. Since the JDM ECU's have a different pinout at pin 114 (WG solenoid vs. ground) I wired the ground directly to the chassis. I have been getting TERRIBLE gas mileage since the turbo. A full tank without hitting boost (barely, if at all) yielded ~20mpg. That seems awfully low to me.

Current wiring (wire colors coming off oxygen sensor):
black: center wire spot for signal
red: to the right of the black wire with the release clip facing upward
white: direct ground to chassis

Now, the way I see it is there are a few different ways to explain all this:
1) Wiring is flat out wrong.
2) Wiring is correct and I'm running SUPER rich for some reason.
2a) Fuel pump, fuel pressure wrong (stock pump & FPR)
2b) Injector o-ring leaking even though I have checked, injector stuck slightly open maybe
3) Something else possibly

If anybody has any ideas or pointers I will gladly take it and hope it helps or does something different.

Narrowband o2 is useless to look at, its basically an on off switch. I'm guessing you are running rich in the tune. For my own car I just took the o2 out of the tune and the car and tuned cruising in open loop.

I think the black wire is ground and the white wire goes to the ECU.

I thought about trying that, but have no idea how to do it. I had the narrowband hooked up before the turbo, and it read just fine. At cruise it definitely stayed in the "ideal" area on the gauge, and when I gave it throttle it would move up to rich. But that was with the old O2 which was the standard "fat" oxygen sensor. I am now using the "skinny" sensor - I wonder if they work differently? Also - I am running a stock U13 tune right now. The only thing that has been modified is the timing map since I have a different compression ratio than the JDM motors. So it shouldn't be running abnormally rich in the tune. I'm thinking about playing with my K number a bit... or trying a few other things.



I thought about that as well. Perhaps I will try this. Do you think it would cause strange readings like I am seeing?

It could. While I've not seen a U13 diagram, all of the B13 wiring diagrams I've seen have the white wire going to ECU pin 19 and the black wire to engine ground.

Dave

That is on the wire harness side though, not on the oxygen sensor wires, correct?

Yes, those are the harness wire colors.

Ok, well on a stock B13 there is no ground wire for the oxygen sensor. The middle wire (white I believe) is signal, and the other two are for the heated power element. From what I've read they are non-polar, and the stock O2 sensor is grounded by the exhaust manifold.

Also, I've been looking for a good ECU pinout for each of the B13 ECU, the U13 ECU, and the GTi-R ECU. The usual place I went to to find them all is now down

Anybody have any other suggestions, or experience in wiring up one of the skinny oxygen sensors to a U13 ECU?