NA-T O2 sensors

[Pulley]

Wondering, as the two O2 sensors will be running side by side on the turbo downpipe on the turbo conversion, and no longer have 3 cylinders each but share a common gas flow, why couldn't I just run a single O2 sensor and just use that to feed both ecu wires?

As they ate just single wire O2 sensors

 

(hoping maybe Chris Wilson can help here)

[Noz]

"A New Role for O2 Sensors with OBDII

Starting with a few vehicles in 1994 and 1995, and all 1996 and newer vehicles, the number of oxygen sensors per engine has doubled. A second oxygen sensor is now used downstream of the catalytic converter to monitor the converter's operating efficiency. On V6 or V8 engines with dual exhausts, this means up to four O2 sensors (one for each cylinder bank and one after each converter) may be used.

 

The OBDII system is designed to monitor the emissions performance of the engine. This includes keeping an eye on anything that might cause emissions to increase. The OBDII system compares the oxygen level readings of the O2 sensors before and after the converter to see if the converter is reducing the pollutants in the exhaust. If it sees little or no change in oxygen level readings, it means the converter is not working properly. This will cause the Malfunction Indicator Lamp (MIL) to come on. "

[Noz]

what i think that's saying, is the second sensor relating to cat emissions is not required. i wouldnt run 2 outputs from 1 sensor, that would probably adjust the output from the sensor if the ecu has any adjustment on the sensors voltage/current for each input.

[Pulley]

But the two sensors on the NA are both before cat, and as the exhaust stream to which both sensors will now be located are next to one another (not like they were originally, one for front 3 one for rear 3) surely both O2 sensors will ve giving the same output anyway,

[JasonR24]

I thought the first cat was before the first cat and the 2n was before the second cat?

[Pulley]

On the na there are 2 o2 sensors (at least on j spec) one on the front 3branch, and one on the rear 3 branch, those two branches then join in the front part of the first cat, then just after the cat there is a therm sensor (that lights up the red cat light for overheating cat) and no more O2 sensors after the cat

[Nic]

I thought the first cat was before the first cat and the 2n was before the second cat?

 

On the 2JZ-GE the O2 sensors are mounted on the 2 exhaust manifolds, only the UK spec Supra has pre and post cat O2 sensors

 

http://static.zooomr.com/images/9761176_06c815a7f7.jpg

Edited October 5, 2012 by Nic (see edit history)

[Pulley]

Yay a pic, that explains it clearer than my words

[Nic]

Wondering, as the two O2 sensors will be running side by side on the turbo downpipe on the turbo conversion, and no longer have 3 cylinders each but share a common gas flow, why couldn't I just run a single O2 sensor and just use that to feed both ecu wires?

As they ate just single wire O2 sensors

 

(hoping maybe Chris Wilson can help here)

 

Will you not be using an aftermarket ECU which would negate the need for the stock O2 sensors?

[Pulley]

I'm going to be running a piggy back injector (slave) system to drive another bank of 6 stock injectors, supplementing the fuelling based on rpm/boost

So the stock system will remain

I've got a HKS AIC 3 controller I've modified

Edited October 5, 2012 by Pulley (see edit history)

[Noz]

Ok, pre cat sensors are a different matter mate. I've looked into this further, found this as well:

 

http://www.performancemotorresearch.co.nz/forum/showthread.php?t=1470

 

Also, my downpipe 2jzge has two o2 sensors in it. As you are using the stock ECU, you need to keep both sensors. Emanage doesnt work like a standalone, AEM would mean you could only use 1 sensor.

 

I would extend wire, it seem's there's no easy way around it.

[Pulley]

Cool, that post basially confirms I can use one O2 sensor and split it's narrow band output to feed the stock ecu

As it happens one of my two O2 sensors is a wideband greddy afr setup which has it's narrow band output tapped to feed the ecu atm

So to save me having to still run the two (one wideband tapped) and one stock narrow band sensor, i will just use the greddy afr wideband O2 sensors narrow band output to feed both inputs of the stock ecu

 

Cheers for the link Noz, that basically confirmed wot I thought

[-Welsh-Stealth-]

I run the 1lambda and all is fine. If you look at the lambda positions on the NA exhaust they're the same place for the 2 different manifolds. As its a downpipe(1single pipe) both lambda wires to the same O2 sensor should be fine.as long as the ecu has a signal from a lambda.

Apparently there are cars in the pipeline that are going to have lambda sensors all the way along the exhaust. As some cars can even completely turn off injectors to limp the car through an MOT on emissions.

Short of it: 2 pipes-2sensors

1DP-2wires to 1sensor (reading O2 mixture& sending signal to the ecu)OKAY

[Pulley]

Cheers, confirms my thoughts, I will be running a single downpipe lambda wideband that feeds my afr and using the narrowband tapping from it to feed both inputs to the stock ecu