AKGC

me neither.

o2 sensors only have 4 wires running off of them. 2 for the actual o2 monitoring and 2 for the heater element to get them to operating temps on cold starts.

BadBoyBill

Yes sir, but primarily for Catalyst overheat prevention/protection.

There are other calculations that are done based on the EGT of the secondary
02 as well but i haven't found any way to really use that data.

finnfrog

So is it bad of the primary o2 sensor of dead ?

__________________
Dead travel Fast

cdnsigop

How is the egt measured? Is there a thermocouple somewhere? Or is it a calculation between the 2 o2 sensors?

BadBoyBill

That i couldn't tell you, however it's calculated it's pretty damn accurate, as
you can see it if you hook up a OBDII scanner that shows realtime data.

What i'm assuming is the secondary is an EGT not a wideband and the primary is
the wideband.

genjuice

Both 02 sensors are narrowband sensors.Those values are commanded values .Both the sensors read egt. In the city close loop driving I see less then 20 degrees diff from the two.

cdnsigop

Where is this described? I went through the entire service manual, and could find nothing on EGT. From my past experience, those stock o2 narrowband sensors have no way to measure EGT. Of those 4 wires, 2 are for the heater circuit, 1 is o2 signal (0-1v), and one is ground. That is, IIRC...

finnfrog

So is out bad if that are dead , my primary is dead and I'm debating fixing it

__________________
Dead travel Fast

cdnsigop

The car is designed to run with the factory primary cat. You leave some power on the table, but IMO, it is worth it. No CELs, no questionable side effects of the ECU's failed primary cat strategy. Even with my GT2860, Im running the stock primary cat (secondary is deleted)...

When my upgrade TD04HL-19T arrives, Ill STILL run the primary cat. Its a street car. It needs to pass a sniffer test every 2 years. $30K street driven sports cars shouldnt have CEL's, or other crap, IMO. They shouldn't fail sniffer tests. They shouldn't have ANY hiccups. Otherwise, the upgrade strategy has failed the car and the driver. IMO. My tuning philosophy IS to improve the factory's product. How has it improved, if you have to live with a bunch of quirks that werent there prior?

All this is in my OPINION. Some are willing to put up with lots of 'quirks' for an extra 20 hp. In my experience (10+ years of turbocharged goodness), those extra 20 hp are just not worth it.

Wellmine

Im not running the stock primary cat, but what cdnsigop has described is representing my philosophy with this car and also the reason why i went with a high-flow cat. I've passed an emission test with it and has no CEL whatsoever. Happy customer

1slogencoup

cdnsigop

Thank God for high flow cats LOL. No CEL, that is an upgrade I could live with!

Mcmonopoly

I have a scantool with live data display and you can in fact see both temps in there. So yes there's a way the ECU sees EGTs.

__________________

cdnsigop

I believe you! Just scratching my head on HOW.

On another note:

I have spoken to Mark over at TurboXS. They are willing to supply a tune for the TD04HL-19T, once they get a Gen Coupe over there with this turbo upgrade. So this turbo upgrade will soon have a TurboXS tune available, for those that want to rock that.

I have also removed my Magnaflow cat back exhaust, and returned to stock (with stock downpipe, and gutted secondary cat). Power is not noticebly different. Car is quiet though!! Lovin it.

Mcmonopoly

Well if there's 2 wires used to supply the heatercore of the sensor, then if you supply a constant voltage/amperage, you can monitor for changes in the actual current and extrapolate temperatures from that, since temperature changes in metal usually changes the conductivity ratio of the metal, which can be seen by the changes in required current readings.

This is my opinion on how the ECU can see EGT through the O2 sensors.

__________________

smoke

you got PM's

__________________
Stage 3

Rspecwhite

My thoughts exactly.

__________________
DIY built motor with haltech


new 19t v2 fs

"Information is not knowledge. The only source of knowledge is experience." Albert Einstein

Rspecwhite

Larger wheel = cooler/denser air= leaner afr. My logic, (and motor) are fine. lol

__________________
DIY built motor with haltech


new 19t v2 fs

"Information is not knowledge. The only source of knowledge is experience." Albert Einstein

genjuice

x1 to Mcmonopoly

This is nothing new, Heated O2 sensors need to know when to turn on and off and it is done with voltage parameters.There is a MAP in the ECU that expands on those parameters to determine EGT.

cdnsigop

Thats a cool setup..

I remember the WRX's had a factory EGT sensor, IIRC, it was for cat protection as well.

Smoke!! Clear your inbox man!