silverstreek81

yes i searched, but like alot of times.... not a clear cut answer.

*see post 10 for new update*

virgineg6

Upstream. You have no idea what they mean by upstream, downstream do you?

silverstreek81

yes i do.

virgineg6

Does your exhaust have a location for both or only one?

silverstreek81

only for 1. should only be 1 since as far as i know the b16 sir II only came with 1, 4 wire o2 since its obd1. unless i missed something when i read up on the motor months back when i first got the car.
i was mostly just unsure if there was some difference in like voltages or wiring of the del sol vtec up and down stream o2's... didnt think it would have 2 oxygen sensors since i thought it would be obd1 being i looked up 95 model year. i think he said 99-00 si showed 2, but one was a 2 wire and the other was a 4 wire, which is what i needed.

i thought it was odd that he was told you're not supposed to solder the wires on an oxygen sensor... didnt think it would hurt anything.. but maybe if you get the wires too hot, might mess up the heater.. could explain the code 41. i dunno...... too much speculating, just need to buy the right damn sensor and try it out.

Former User

Diagnosis -- Measure the resistance of the heater element of the O2 sensor.

It is fine to cut and splice wires for the heater element, if done correctly. Wires for the O2 sensor itself are more tricky, but can also be cut and spliced.

silverstreek81

yeah saw that on the fsm... says gotta be like 4-10 ohm.....

i know you could cut and splice the wires probably no problem... but is soldering them together bad? thats what he was told after he did it and it would throw a cel occasionally on deaccel and when i could get it to go into diagnostic mode, i think i recall that it did have a code 41. just never heard that you cant solder the wires, maybe it might be true, it will get too hot and mess up the heater part of the o2?

Former User

10-40 Ohms

The only way to splice the wires is to solder them. Then insulate the soldered splice with shrink wrap.

silverstreek81

oh ok, i couldnt remember the numbers exactly... was kinda close, haha.

see for the splicing the wires, i've never heard you cannot solder them, but a few people said you cannot because it can mess up the heater part of the o2. thats what my brother in law was told after he did the the swap and had to relcate the o2. it throws the code occasionally on deaccel for me, but since i just got my neptune rtp/demon setup i've just turned off the o2 for now and haven't been driving the car. i would think you could solder them, just dont let the wires get hot.

i guess i'll just buy a new upstream for a 99-00 si and see if that fixes it. and i'll test the old one and see if it's not within the 10-40ohms and if it's not i'll toss it.

silverstreek81

ok, i know i made this thread months ago, but i finally have had time to look into all this stuff and still having the same issue and i'm just totally stumped.

i bought a new 4-wire o2 sensor, installed it, reinstalled my p28 ecu that's got neptune rtp/demon setup on it and still getting code 41. for now i've got o2 heater disabled but still have it enable closed loop, not sure if that even works or not, but if not i'm not driving the car til i get this resolved anyway, so shouldn't be a big deal.

i have followed the flow chart from the fsm for code 41 and everything checked out. i checked the orange/black wire and yellow/black wire, as those 2 are the one's for the o2 heater. i checked them both all the way from the ecu to the sensor for the org/blk and the ecu to the main relay for the yel/blk. i had continuity all the way for both.

i sent the ecu back to hamotorsports (whom i bought it from) and they tested it and it checked out just fine, so shouldn't be the ecu. but just in case, is there any way to test the ecu itself and see if there's maybe something wrong with that part of the ecu that controls the o2 heater?

i'm really just stumped here, should be an easy diagnosis and fix and it's not. 95 civic dx coupe's with d15b7's had 1 4-wire o2 correct? not seeing anything that says otherwise, so i'm pretty sure there's not some other hidden harness and i've plugged in the wrong one.....

egsleepercivic

http://www.amazon.com/Denso-234-4011...2751480&sr=8-1

HondaPartsHero

So you're saying you have no more connector but the wires from the harness are soldered directly to the 02? I would try another ECU just to eliminate any possibility.

silverstreek81

i've already got a new o2 sensor, but thank you.

no no.... i've cut back enough of the wire loom to hook the wiring harness for the o2 directly up to the o2. i can take a pic if need be, but it's hooked up just like it would have been with the d15b7. it's not soldered, matter of fact i'm 99% sure the o2 that egsleepercivic provided a link to is the same denso o2 i bough from partsgeek.com. blue, white and 2 black wires. and both the black wires are connected to the org/blk and yel/blk and are not crossed as it's hooked up just like factory. again, i can take a pic and post when i get home for lunch, just for a visual, but don't think thats necessary.

Coupe-R

You have a P28 right, this is from a SOHC vtec correct?
they don't have internal control for a 4 wire heated 02 sensor.

you need to add this to the ECU. Check pgmfi.org
prob why you getting a oxy heater error.

Also you will damage the 02 sensor after long use without the heater enabled

silverstreek81

i've looked all over for this reference... so p28 ecu's don't have internal controls for 4-wire o2's?
i'm looking on pgmfi.org right now, but just in case i misunderstood... you're saying i can add the internal control stuff to the ecu? i thought that all obd1 cars had 4 wire o2's except the VX (think it was a 5 wire???).

i know the p28 doesnt have the ability to do a knock sensor, but didn't know it couldn't do 4-wire o2's. so guess i'll have to just disable it in neptune and baby it til i figure out how to wire in my innovate mtx-l as both wide and narrow band.

so this won't affect my future tune when i slap on my turbo kit and take it to be tuned. i'm all for making more power, but i want it safe and still driveable, not making alot of power when at wot, but then running rich and bogging when idling or just cruising.

silverstreek81

anybody else have any input? i've yet to see anything that says p28 ecu doesn't have support for 4-wire o2 sensor. need to get this figured out!

KoNEY

p28 is 4 wire 02, cx/vx were 1 wire. I would check the wiring at the ECU, make sure everything is checking out like it should. Probably the ECU.

silverstreek81

ok thats what i thought as everywhere i've read, they support 4-wire o2's, but i was just trying to reconfirm in case i missed something.

anyway, bumping again. gotta be somebody out there that has had this problem and solved it, other than just swapping ecu's.

Coupe-R

Ok glad that is cleared up, we don't have P28 ECU's on JDM cars where I am.

However SOHC vtec JDM is SINGLE wire.
DOHC is 4 wire.

It looks like USA got 4 wire heated 02 on their SOHC vtec's.

Sorry for the confusion. So its either your wiring, or 02 sensor, slim chance its o2 but try that LAST.

silverstreek81

the o2 is brand new and tested good. the wiring all tested good as well. really leaning toward the ecu, but i just sent it off and got it back from HAMotorsports and they said it tested just fine. i'll try to pm them and see what all they tested on it, maybe they didn't test the o2 heater circuit... i just dunno wtf to do at this point.
if i can't turn off the o2 heater part and have the o2 sensor work as normal, i guess i'll either have to send the ecu back yet again for further testing or hope when i get the turbo kit on and have it tuned, my tuner can tune well enough to make it safe and drive/idle normal.

silverstreek81

anbody else have any ideas?