Robert Salvador

Good afternoon!

My goal is to delete my secondary / downstream o2 sensor (or signal) to the DME. I’ve got a 997 GT3 exhaust setup on my 3.4L but having my catalytics deleted I’ve placed the secondary o2 in the exhaust (farthest point from the first o2 sensors). The only reaction to the car is error code and check engine light.

My question: Is there anyway to wire in a loop setup similar to the airbag delete or GT3 wing wiring to avoid the engine light? Or a ROW tune / programming that can be utilized?


Thanks in advance for any suggestions or feedback ✌🏼

-Robert
@FLAT6REBEL

pdxmotorhead

The most common solution I've seen is to put at least 2" of tube between the Exhaust and the 02,
and use one that has that small element of an catalytic converter element in it. You can test it with a durametric or scanner if it can display the actual value.

There were places that sold boxes that went between teh 02 and the ECU and the signal was bracketed in to a "pass" level on the fly so you just ran secondary 02's with the box and the ECU always saw a acceptable efficiency rating. Unfortunately these are now very hard to find as the fed stomped on the folks selling them.

DBJoe996

You do know that the ECU/DME uses the signals from the O2 sensors to detect and tune how the engine runs. Including such things as fuel injector timing and whether the engine is running rich or lean. I think eliminating the O2 sensors is a bad idea and probably would violate federal mandates. But what the heck, your car and your engine. And to the best of my knowledge, US or ROW tunes or programming isn't going to remove the need for the O2 sensors.

pdxmotorhead

This is only about the secondary 02 which do nothing except tell if the cat is working at full efficiency, it does nothing else with the ECU , the Primary 02 is used to adjust the EFI..
This is standard to run track cars evne the $$$$$ porsche cats don't like extended days of WOT.
He's also talking about a GT3 which flagged it to me as a track toy..

I've seen track only cars that Porsche had removed the cats andsecondayr 02 sensors, back before even that was deemed "bad"... Now they wont help even for track toys.

yaz996

These will get rid of the CEL:

https://www.racdyn-usa.com/PROD/130+10+10+014.html

Ghost100

Thank you! A much more reasonable cost than the Fabspeed ones, Google was giving me a hard time locating another option though.

Armitage

When I was getting occasional cat errors, my local indy suggested programming those post-cat sensors out (I think they're part of the "stricter emissions" option which not all 996s have anyway) - I decided to replace the sensors first, but still - you should be able to disable them without mounting any additional devices.

4Driver4

This is correct:
This is not correct:
Yes, the primary O2 sensors provide most of the data for DME adjustments, and yes, the secondary O2's are used to monitor cat health. However simply triggering a CEL as cats fail is not the sole purpose of the secondary O2's. The DME makes adjustments to long term fuel trim using data from the secondary O2's; basically the DME includes cat health/efficiencies into its calculations on fuel trim.

De Jeeper

Well what happens with the row cars that dont even have rear o2 sensors? I guess the fueling programs r different? I personally have never seen an issue in any make of car that has had the rear o2 sensor readinesses turned off.

Either fool the computer or delete the feature with software. Both r effective.

brontosaurus

Why would the secondary O2 sensors be used for anything outside of cat health?

O2 is consumed in the cat during normal operation, It would make absolutely no sense to use a post-cat sensor for anything engine control related as you do not know the relative health of the catalytic converter. The only purpose is to verify an offset between upstream and downstream sensors to confirm that the cat is functioning.

pdxmotorhead

Near as i can tell from the signal voltages the downstream o2's are not fancy, the signal looks like a standard 02 not a wideband or anything..
Can't imagine how they would give any real useful data.. I'll have to look when I pull my next log for the tuner..

Robert Salvador

Thank you for all the input. Going to switch to those 45 degree mini cats. I’ve tried extenders but those didn’t help. I’m mainly looking for secondary o2 sensors like I’m running it with no cats. I think ideally will be a ROW tune