Thread: Regrounding the O2 Sensor

Great V... You are wise... As this is a critical component.
I take some shortcuts to sometimes, but never with critical components...

The 12 Gauge wire is actually great... It doesnt matter which ground that you use on the Intake Mani.. Both are equal.

Maybe you dont have a AIV on your car? On my NX, its in front of the engine beside the OEM Oil dump can. The AIV puts air in the exhaust stream.. I removed mine but Im putting it back after thinking that maybe the ECU is trying to add Fresh Air to the exhaust stream.. Dont know..

Oh yeah I guess In this case it is fairly important to get a good ground, or the ECU might not be too happy. Plus I've been hearing some people fried their ecu by not connecting the ECU wire rightly...

I have 30' of 12 gauge wire that I bought last year when I did the reground, but haven't really used it yet

So with the heater wires, it doesn't matter which one is the which right?



Ohh I don't believe low ports come with those, I've only seen High ports with them. I think the lowports have a similar system on the intake mani's

Yeah the heater wires will be the 2 white wires. Just connect them to your existing 2 whites AND the black signal wire with the black wire. The NEW Gray wire is the one that you need to run back to the intake mani...

When you say AIV, do you mean AICV?

The AIV is beside the oil separator in front of the engine. It was removed after 94 model years. I removed it once but reinstalled it this weekend to perform some testing. See this thread for a picture: http://www.sr20forum.com/sr20de-technical-corner/228118-next-oil-separator.html

Ah okay, thanks Wasn't sure what you were referring to, but I guess it makes sense, since they removed it on 95+ model years.

Is the ECU even involved in that? Off the top of my head, the AIV valve in the front operated from a low vacuum in the signal tube running back to the vacuum manifold on the intake. The tube from the AIV valve to the exhaust injects air downstream of the O2 sensor, so I don't think the ECU would have any direct way of knowing when to open or close that valve. I'll look in the FSM to see exactly how it works when I get home.

Oh yeah I know about those

I just wanted to make sure that the heater wires had no polarity because they are exactly the same colors you know

Btw I'm working from DC today and tomorrow, but I will be going back home tomorrow at 2. My O2 sensor arrived today. The eBay seller is a fast shipper, and only charged $1.50 for shipping!!!! . Also he shipped it that it was even being transported on Sunday... better yet, Easter Sunday!

I was almost right. The vacuum signal to the AIV valve is controlled by a solenoid that the ECU turns on under two particular conditions: at idle when the coolant temperature is between 82 and 221F to reduce precat emissions, and during deceleration to blow water out of the valve. From what I can tell, it shouldn't have any effect on idle speed or any other engine behavior.

Yeah I know right... But just like when I installed my SSAC header, the mpg went down, well the same happened when I removed the AIV, lost more mpg... So, now Im doing some test after added it back.. The testing is pulling DataScan logs everyday on my way home from work and the performing some comparative analysis against Data logs from last spring. You are correct that it shouldnt have any effect on idle speed b/c its after the O2. But, the O2 is still seeing the impact of the air being there somehow. The O2 and AIV header bungs are only 4-6 inches apart. Compared to logs from last week (O2 grounding testing), it looks like during warmup the O2 is readings are different. Maybe my New Header grounds are causing it.. Dont know yet. Its still early. BTW, Im also looking at the ECU mappings (both timing & fuel), to determine the cells being selected.

But with a better ground for the ECU, Im now getting good readings at low rpms and idle...

Where in the FSM describes the AIV functions? I couldnt find it last night..