I believe there are two 02 sensor's. There is one 02 sensor on the exhaust manifold, and then there is another 02 sensor on the cat/midpipe. Correct? Do you absolutely need both of these 02 sensors. I know it "runs" without both of them, but does it harm it, or make it perform any different without both 02 sensor's?

Ohh BTW, it's a '91 240sx KA24DE.


Right now I don't have any 02 sensor's. There is one in the exhaust manifold, but it isn't hooked up, it's blocking the hole though. The 02 sensor for the midpipe isn't there. There is just a hole. I just swapped out engines at home. My car isn't really running right. I'm trying to pick at the little problems, to get it running perfect.


Thanks,
-Jeremy.

 

im pretty sure you just have one in the exaust mani. Dual O2's came in OBD2 cars, which yours deffinatly isnt. So I would say yes if your stock and dont have the correct maps to run in open loop? or is it closed loop lol. Either way its a keeper unless you like paying for more gas than you need at these prices

 

O2 sensors improve gas mileage and emissions, and try to modify the a/f to be as close to stoich as possible. Without an o2 sensor all that will happen is you'll run a little rich (your computers safe mode), probably throw a code and get worse gas mileage...a lot of people bypass the 02 sensor which i don't understand...(i did and wish i didn't). Same thing with the EGR...its all emissions shit...old cars didn't have them...new cars don't need them. That hole in your "midpipe" as u call it is an exhaust leak. block it off.

Matt...starts in closed loop and uses preset eeprom settings for AFR and after it heats up (about 600*) it goes into open loop.

 

have you used a timing light to see how advanced you are? should be close to 15* im pretty sure

 

It's a S14 engine, with the EGR and all emissions eliminated. It's a '96 KA, so would that be considerd OBD-II?

Just for a review, it's a S14 Engine, with a S13 Intake Manifold, but with a S14 exhaust manifold.

With out having either 02 sensor, would my car cut out, and sputter, eventually stalling if not pressing the gas? I believe it's the timing. I havent double checked it with a timing light yet.

Thanks for the advice.

 

the 2nd o2 sensor does nothing. its obd-2 and is used for diagnostics only, just like alot of the other obd-2 stuff.

i wish i had kept my egr and my evap systems...but with a turbo it wouldnt help much.

there is alot of talk going on lately about when removing the egr, the ecu will pull timing alot differently. there has been a few cases of guys running upwards of 300-350hp with only fuel managment and base timing changes, and the no egr having an effect thus allowing them to run in such conditions. not having any egr might could be a culprit, but i think you should look at the timing first. make sure when you set your timing, that you have unplugged the TPS sensor and have adjusted the idle to 700 RPMs +/- 50 variance...then set it to 20 degrees BTDC.

 

the car is still OBD 1!!!!! why do people think that just bc it has a newer motor, that some how magically, the computer morphed to a newer style?! look. KA's run great w/o O2 sensors. fuck them all! other wise, one 1 wire sensor in manifold