ugabuga

Ok, so both sensors are 2 wire heated sensors.

Rear sensor is cheap cheap , front sensor price is $150+
I was wondering if anyone has tried using a rear sensor as front by splicing the wires in or using a universal O2 sensor?

Are the sensors indeed different?

RIWWP

iTrader: (2)

Yes, they are different. The front is a wideband sensor and the rear is a narrow band sensor, hence the price difference. If you use a narrow band on the front you run a very big risk of blowing your engine, as the voltage signal to determine AFRs is the same between them, but the ECU interprets the voltage differently. 0.9v on the front is way lean, 0.9v on the rear is only modestly lean.

Just get the proper O2 sensor.

ugabuga

I've been reading on all kinds of forums and it turns out the front sensors on some cars are what they call AFR (air/fuel ratio aka wideband) and the rear is a plain O2 sensor.

The rear sensor just needs to know if fuel is burnt properly.
The front actually needs to give the ECU exact afr information.

I may have answered my own question but I'll leave it just in case someone has other info.

RIWWP

iTrader: (2)

I admit to chuckling a bit

AFR is indeed air-to-fuel ratio. However, you can only obtain this information through an O2 sensor. Both narrowband and wideband report information that is converted into AFRs (or Lamba, which is a different measuring scale of the same thing). They both work exactly the same way, and are used exactly the same way by the ECU.

Wideband vs Narrowband is exactly what the names describe. The wideband reads AFRs between 9.0(ish) and 20.0. The narrow band only reads between about 13.5 and 15.5 (ish, I don't know the precise min and maxes for narrow band).

Narrow band sensors respond faster than wideband, and offer greater precision for fine tuning AFRs, but due to their narrow range, they are largely useless for any proper engine tuning. Most piston engine cars only have narrow band, front and rear, because running it out of range isn't immediately harmful, and the ECU can take the time needed to trim the fuel to get the AFRs back in range. It can take longer, because the ECU just knows that it's reporting too lean or too rich, but not how much so. And it can take time to trim it back in range when it's only adding fuel to bring a 13.5 to a 14.7 for example, when it may actually be an 11.0, and it needs nearly 3 times as much fuel trim to get it on target.

Proper engine tuning often is targeting an AFR outside of the narrow band's range, and obviously the narrow band become inappropriate then. A rotary is way too sensitive to wrong AFRs, so a wideband is needed. Same with boosted cars. Target AFR is boost dependant for the most part, and usually targets in the 11s or 12s, way outside of what a narrowband can achieve.

DRKSYDE

iTrader: (1)

RIWWP,

Can you possibly shed some light on this for me?

I too "think" I need a new upstream sensor. Here is my symptom: 2004 with Bad idle and stall.

When I cold start it, it runs fine. Once hot is the problem. When you turn on the A/C compressor it idles better due to the computer adjusting the fuel to compensate for the increased drag on the motor.


Here are the things I have checked and or replaced.

Engine was replaced 38k ago under warranty. Car has 104k.

New plugs and coils and wires. (BHR Upgrade)

New MAF Sensor (after I cleaned the old one)

Full vacuum test - no leak

ESS NVRAM Clear (several times)

Full TB clean (removed and cleaned by hand)

I have a Agency Power Resonated cat delete pipe so no clog on the non existent cat.

Car is never driven in winter so no corrosion on the wiring harness.

I have the stuff to do it, but have not done a Sea Foam to it (yet) due to the relatively new motor.


Here is the thing that led me to believe I need the sensor. I hooked the car to my phone and the Torque OBDII app and mapped the sensors. My rear narrow band o2 sensor was giving me a reading, however my front was not.

The only reason I question the app reading is I wasn't sure if the app was capable of reading a wide band AFR/o2.

Any suggestions? I am at my wits end.

RIWWP

iTrader: (2)

Yes, you should be getting a front O2 signal. I did on Torque with my 8. It could certainly be causing the problem. Are you getting a "commanded AFR" and "actual AFR"? If so, what values at idle.

DRKSYDE

iTrader: (1)

I will have to take a look. It was a couple weeks ago. Its not my primary car (I haven't even driven the poor girl this year more than a few feet and enough to keep the fuel (with stabilizer in it) from clogging up my injectors and such.

Thanks for the reply. I will try to get that reading for you in a couple hours.