OXYGEN SENSORS

[kerrynzl 3]

Knowledge Wanted!

I'm fitting a complete 1996 E36 M52 [328] exhaust system to my 320 E36 coupe, I inherited USA M3 tube exhaust headers with the swap

[Now my Question]

The 320 has a single O2 sensor in the system just in front of the Cat-Converter, The 328 has twin O2 sensors in the headers [both are using Siemens electronics, both have the same colour code wiring on the sensors]

Can the Twin sensors be wired together [parallel] and spliced into the original harness [and still work correctly?] O2 sensors convert to "millivolts" not amps so I assume they can be wired together parallel[not in series]

I can use one sensor [which one, front or rear]& plugging the hole,is more hassle to me,than splicing the loom.

Any solutions are appreciated [quickly before I revert back to being a 'Carb & Points Moron']

Thanks Kerry

[2002 1]

I'd be inclined to try wiring up just one of them and see how it goes

[kerrynzl 3]

I'd be inclined to try wiring up just one of them and see how it goes

Yeah, I was told that by my EFI [racing guru] about 10mins ago.In simpleton terms he said the O2 sends a lean or richen signal [command] to the DME having two sensors wired parallel could cancel each other out [we're talking millivolts here]

on a Honda there are two banks of injectors and two O2 sensors [one each] The fun starts when the O2 sensors are wired diagonally [by a DIY expert]

Thanks for your reply KERRY

[cainchapman 0]

I would wire them up in series as my first option. This will do less damage to your electronics if you are wrong.

Rtot=R1+R2, so if each sensor has 10 ohms resistance, 10+10 equals 20 ohms Total.

If you wire them in parallel, however, 1/Rtot=1/R1+1/R2, so using the same 10 ohm resistors. 1/10+1/10=2/10 or 1/5. So you actually end up with 5 ohms. This may cause excessive current to be driven through the circuit.

[kerrynzl 3]

I would wire them up in series as my first option. This will do less damage to your electronics if you are wrong.

Rtot=R1+R2, so if each sensor has 10 ohms resistance, 10+10 equals 20 ohms Total.

If you wire them in parallel, however, 1/Rtot=1/R1+1/R2, so using the same 10 ohm resistors. 1/10+1/10=2/10 or 1/5. So you actually end up with 5 ohms. This may cause excessive current to be driven through the circuit.

HOW DO YOU WIRE THEM IN SERIES? I assume the heaters are wired in parallel, [they are four wire sensors] & the O2 sensors generate volts [to be read dy the DME] Wouldn't it be the same as [for example] stacking two 1.5 volt batteries in series to get 3volts? The DME would automatically 'think' the engine is running too rich, & try and lean it out.

Please correct me if I'm wrong [before I install a Holley Flooding System Haha!]

Cheers KERRY

[cainchapman 0]

I have no idea how they work. As an Electronics person, I was only recommending not trying parallel first.

Conrod may be able ot shed more light on their operation and integration with any electronics in the ECU. You could look at the wiring diagram in the Haynes manual.

Actually, another thing with parallel circuits is that you will get an equal volt drop across all equal points, so 2 wouldn't be of any assistance to you IMO.