Hmm well it seems honda wants 10-40 ohms across the heater and my bosch universal O2 sensor has 3.7 ohms across the heater... hmm... I fear I'll burn out the driver if I hook it up

 

Yes I was just discussing a resistor with someone to address this very problem. The OEM sensors have a resistance of roughly 14.3 ohms.

 

dustin,

read up a few posts. I had the same problem. I hooked it up and it didn't burn anything out but I still get the CEL for the heater. 3.7 ohms is what mine has too. I guess I'm gonna have to try the 10 ohm resistor. Weird. Hope it works.

s


[Modified by stevel, 2:13 AM 9/24/2002]


[Modified by stevel, 2:14 AM 9/24/2002]

 

Hmm what wattage should the resistor be?

Also, does anyone know where the heater gets +12v from? The black/yel wire in the Helm diagram is connected to [A] whatever that means. Most confusing diagram in the entire book. I'd just hook it to the +12v switched at the ecu but I fear I'll blow the fuse... I'd rather hook it up as honda intended..

 

It's supplied voltage from the ECU. Blowing a fuse could well be the very least of your worries. The "A" is almost certainly the designation given to one of the connectors to your ECU. Both the + and - wires from your sensor can be traced back to the ECU.

As to the wattage, I doubt you'd have trouble with even a 1/4 watt resistor. Perhaps you could wire up 2 5ohm 1/4 watt resistors in series or 2 20ohm jobs in parallel , since these are about the most common.

 

Not according to the diagram... +12v comes from somewhere else. Pin A6 (obd1 ecu) supplies (-) to the heater circuit. The Diagram has [A] through [L] or something like that, and they are reused on different parts of the diagram for different things. I could just hook it to switched +12v anywhere, but I thought the heater circuit pulled a couple amps?

 

Well I don't have the diagram you're looking at in front of me, but I can tell you what my experience with this circuit is on my '96 GSR with stock ECU. In order to trace those wires I looked for suspicious wires at the ECU, connected long leads to the + & - terminals of the secondary O2 sensor socket and connected an ohmeter accross wires till I found the 2 that had 0 resistance. The difference in volatage potential across these 2 wires at the ECU was identical to the voltage at the end of the long leads connected to the secondary O2 sensor socket. Thus I can say with absolute certainty that my car's secondary O2 heater sensor circuit receives it's current from the ECU. Now while this may well be different with OBDI, and I never toyed with this on my '95 GSR I don't think I'd be rewiring this if I were you.

If you're determined to do the math(P=IxE) then rather then guess what current it will draw just connect a meter to it...in series of course.

 

Well the car is a '88 CRX Si with the 88 wiring harness. Using an obd0->1 conversion harness with P75 ecu. I don't have a secondary sensor... this is the primary O2 sensor. The stock sensor in the car was a 1wire unheated sensor...... So I get to do the wiring.. hehe.

It may very well get its power from the ECU, but it must just tap into another +12v lead... it doesn't have it's own 12v source... Hmm. I think I'll just try tapping it to the pin I used when I wired in the electronic VSS for the car... It has +12v from ign1.

 

So having my 02 sensor bung welded about 6" from the turbo on the downpipe can cause the sensor to prematurely burn out? Makes sense, I think I'll be welding a new bung further down.

 

Hi Stormin,

Chemical Kinetics..Chemical Kinetics................it cost me about 2500 bucks to learn the statement I made about CO, when Intellictual Property costs me, its source stays with me...........sorry.

Note I did not say it measures the CO concentration..........let me say, try an O2 sensor in pure hydrogen combustion and then tell me if you know if it is rich, lean or stoichiometric.

Regards,
BigMoose


[Modified by BigMoose, 10:26 AM 9/24/2002]


[Modified by BigMoose, 2:29 PM 9/24/2002]

 

Turboeg,

Can't say for sure without the thermocouple data. Stay within the limits I posted and all will be well. 900C and above is the red zone. Don't move it if it works. If you have problems, then you may have an indication of the problem.

Regards,
BigMoose

 

hehe, thanks alot TimoneX..

 

hey guys im running a zc motor...witch has a 95 civic comptech 421 1peice header...which means the o2 sensor is next to the cat not on the upper portion of the header...ive been getting the code 1 since ive had it...so can i switch to a heated o2 sensor..?

my car doesnt stutter or anything just gives the code.
if i can use a heated sensor..how do i wire it up??

 

Ok, I wired two 22ohm 1/2 watt resistors in parallel to the black/yel wire at the ecu and connected one side of the bosch heater to this. I connected the other side of the heater to the heater driver output at the ecu. Total impedence across the heater w/ resistors was about 14 ohms. No CEL, O2 works fine

Thanks for the help.

 

Happy to help bro.

Cheers