Thread: Regrounding the O2 Sensor

What advantages and disadvantages does the Auto vs Manual ECU have in the testing off top you think? A lot of people don't know that you have a AUTO NX Scotty and manuals are known for getting better gas mileage even it the cars have everything the same even the curb weight MINUS ecu/tranny.

You are correct: Overall Gas mileage is always better in the Manual Tranny. And the MPG improvements should be a little better for manuals but not that much. Vadium is doing the manual testing on his car. Im expecting others to post their results as well.

Vadium: 99 Sentra ODBII Low-Port Manual
Scotty: 93 NX2000 ODBI High-Port Automatic

In my opinion, the major differences appears between ODBI and ODBII cars (high port vs low port). Thats where I believe the most differences exists and is reflective between my car and Vadium car.... Other factors are the condition of engine components, tuneup parts condition (plugs, rotor, cap, oil) and overall tuning setting (TPS, timing, MAS ground, etc.).

But, the test results should not be affected by that at all. Both should show if the mod provides improvements. Im keeping logs of my present mpg. Upon applying the mod, the improvement percentages will be provided with the differences found without changing other stuff. The ECU learning mode, O2 sensor and other impacted sensors are the same between Auto/Manual with no differences in operations. The TPS is the only sensor that is different as it has an extra module to determine open/closed Throttle plate. More differences are found between high & low port engine setups. But if the O2 sensor is isolated as the only change, the differences should not pose an impact. Note: The SR20 bogging problem are also inherent on the Auto Trannies too, as I have that problem too.

So if I have major improvement on my auto, the people with manual trannies should see a slightly higher improvement. Remember at one point, I too was averaging 34 mpg with an Automatic & base timing of 15deg.. So auto trannies can get great gas mileage too...

Wow it was that high? What did you do to get it that way? Was this before or after you started the O2 sensor testing? That is awesome. Why is that in the bold red?

That was in 2005 & most of 2006. BEFORE testing the O2 sensor mod. All I did was keep it tuned, changed the synthetic oil, cleaned the throttle body annually and kept the timing @ 15deg. Bogging & mpg dropped by 10 mpg started in late 2006 after installing the SSAC and SS Catback.

I started trying stuff in Spring 2008 as the problem got worst in Jan.

Dont know why it showed up red... Made some corrections... Please Read again

Also: Everyone should read my post #142 as a precaution. Running Lean is very bad on the engine....

Yes, so far the best I've gotten is 38MPG. Now this is with another mod present, so I dunno how much it is helping the MPG's.

Right now One of the exhaust flanges ripped off and took a chunk of my exhaust with it, so I got a dime sized leak thats been killing my car and gas mileage...

After today I should be driving with a bigger resonator to, from 2.37" ID and like 3" resonator piece, to 2.5" ID with 6" Resonator. This will probably eat all of my low end torque along with some MPG's. But we will see I guess

^6"? <---inch? You doing this for noise reasons?

Yes sir, can't stand the raspyness anymore!

This is why we need more OBDII Lo port testers...
Vadim is doing multiple stuff to his car simitaneously...
We will never know if the O2 sensor mod actually improved anything...

This is because Vadim wants a 50 mpg Nissan...

I ordered the 15727 last night. I am still chasing CEL's though so it might be a little bit before i can get a base line. I should have all the CEL's fixed now but i have not driven the car much since to verify. It usually takes a day or 2 for them to come back on. I will start driving it tomorrow and i will take it for a joy ride tonight to see if i can get it to come on. I was having an EGR and rear O2 lights. I faked out both so it should be good.

Haha true yes we do, in fact a lot of things has changed since i first bought the 4 wire O2 sensor.


I will say thought, with 3 wire I used get about 30 MPG if I'm lucky. 19MPG city on average.

With the 4 wire O2 sensor, thimble (not plano), I got 33 MPG. Got 23MPG city once.

Now with Plano, the first time I filled up I got 30 MPG city. After it was much lower then that, more like 22 MPG City. Recently I got 27 MPG for highway with heavy traffic, and on the way back I got 38MPG (pure highway and some lead footing)

So so far Plano has been the best. But a lot of things have changed in my mods, why? Because I can't sit around wasting $4 on gas, so I will do what it takes to get more ASAP