REDTOP BLACK TOP O2 SENSOR DIFFERENCE.

[slviadrifter93]

Hey guys, Ive been on NICO for a while but this is the first time im actually posting. Ive tried researching this but I haven't really gotten a straight answer. I have a red top sr20det. It has a 2871r turbo etc. My problem is that two years ago I passed emissions I AZ with a skinny O2 sensor. This time I had to buy another, but the sensor itself is a lot fatter. It has three wires just like the old one and an identical plug for the harness. I wanted to know what would this do to my emissions readings because I went in after I put in the new 02 and all three failed as opposed to the run before where only NOx failed. The first run I was running stock fuel pressure and no 02. this new run I put in the new o2 and turned up my fuel pressure a bit. I am at a loss and I don't want this to turn into what it did last time which was going through emissions 8 times before it finally passed.

[Nikita240]

You just plain won't pass NOx with an SR. I don't know how you passed originally. It must have been a huge fluke.

Redtop's use skinny sensors and blacktops use fat sensors.

[slviadrifter93]

Nikita420 Thanks for the reply. I beg to differ with the nox test because I have done it before. The car was tested 8 times total 7 of which the nox was high. the way the car was tested never changed. I put in a new skinny o2 sensor and played with timing a bit and the car ran not only cleaner but enough to pass emissions with flying colors. You didnt answer my question though because i asked what will the fat o2 do to the redtop ecu. Will it send wrong frequencies to the ecu or? I know the car will pass i just want to know if the o2 sensor i just bought for 73 dollars is doing what it should.

[Nikita240]

I think it would run exactly the same. All O2 sensors are basically the same. You can even buy universal ones for like $5. If I had to guess, I'd say the differences are in the thread size, connector length or connector type. But the voltages should be the same. O2 sensors are analog. They simply produce (yes, they actually produce their own voltage) between 0 and 1V.

Running the car rich, you risk failing on CO2 AND HC. Same thing from retarding timing. The things that will make you pass NOX are a good EGR and CAT.

[slviadrifter93]

I have no egr system hooked up. I have a california spec cat that i bought brand new 2 years ago for this specific purpose. ran the cat for the time i needed emissions and then it came right off. So let me ask you this. At 37 lbs of fuel pressure at idle the car ran the 2 pass one fail test. I tried it at 47 today because thats where i usually keep it and the car failed all three. the nox went down significantly but it raised the others pretty good. I retard my timing, change my fuel pressure and run the cat. It worked before im trying to look at the inconsistencies in the motor since last time and the only thing thats different is an adjustable fpr and the bigger 02 sensor.

[slviadrifter93]

edit: i usuually run 57 lbs at idle. so i decided to split the difference at 47