RomRaider

Is there a way to delete/remove the inputs from the rear o2 sensors on the 350z or G35? I have an AC810 ecu if that helps at all. Thanks in advance.

Yup! While disabling the DTC’s potentially could remove all functionality, there’s also an O2 sensor position supmask that should guarantee they aren’t functioning. What I did, however, was more precise. I went through the code and disabled anything narrowband related, including the catalyst compensation on warmup. (Running resonated test pipes) So even if the supmasks didn’t fully disable them, my code modifications surely did. What’s nice is that my code modifications kill the input completely. So the narrowbands constantly read 0V, rather than showing proper voltage like with adjusting just the DTC’s.

Thanks!

That's essentially what I was looking for. I have one narrowband that will read similar to the other bank but will randomly max out voltage at idle. This starts to throw that one bank out of whack over a short period of time.

I am running test pipes as well. I have defoulers on the narrowbands but the one, every once in a while, will freak out and go max voltage. Replaced it and still experience the issue. I've tested the circuit multiple times now and everything seems to check out. Rather than replacing the ECU, I thought this route may be better. I'll see if I can find the "supmasks" you are referring to in the forum. I am new to this so not familiar with it.

I could define em for your ROM pretty easily whenever I get the time. The DTC’s are already defined (check my repo on GitHub for the current definitions), but the O2 sensor placement one isn’t currently added to the definitions.

One of my narrowbands failed so rather than replacing it, I just disabled the narrowband logic They’re not doing much with the extended bungs, so no point in replacing them.

That would be awesome sir. I'm guessing you just need a link to my ROM or would you just modify the definition for my ECU?

I should already have either AC810 or AC81A, as I have a standardized definition file for them. So I’ll just modify the definition file. So all you should have to do (when defs are updated) is disable the narrowband DTC’s and remove the narrowbands from the O2 Sensor Placement flag/supmask. That SHOULD disable the narrowband logic.

Awesome. Thanks dude. I'll keep an eye out for your reply.

I believe I found your github:

https://github.com/Pytrex/NissanDefinitions/tree/master/Nissan-Definitions

Yup! Just defined it for your ROM, so download the latest defs and you'll be set!

Ha, just realized your github is in your sig. Derp.

I'll give it all a try tonight. Thank you again.

Actually, I decided to add it to my signature after seeing your message haha So it was a recent addition But definitely keep me updated! Could you try out a few things for me? I don’t have a back to stock patch yet, so it would be easier just to have you test some stuff out rather than making an entirely new patch.

If so, here’s what I’d appreciate you checking out after disabling the DTC’s and flag;
- Do the narrowbands still report a voltage reading, or do they get 0’d out?
- If the narrowbands still report a voltage reading, does your engine run fine even when the narrowband goes max voltage? (If it runs fine, this means that the flag and DTC’s fully disable narrowband fueling compensation)
- Do any of your emissions monitoring tests get disabled? (Do a before and after check, anything that gets disabled will show “Not Supported”)

Personally, here’s what I think will happen. I think the narrowbands will report a voltage reading, but they won’t affect fueling anymore due to the flag. Then, due to the DTC being disabled, it’ll disable one or multiple emissions monitoring tests. But we’ll just have to see!

Right on. I'll see what I can accomplish this weekend. I'm still learning this stuff so it'll probably take me a bit. Thanks again.

I think that the mO2S byte specifies O2 sensor existance, regardless of sensor type. Vehicles that do not have wideband sensors still use bit 0 and bit 4 to specify that they have sensors in the "sensor 1 bank 1" and "sensor 1 bank 2" position.

Calling it AFR Sensor Bank 1 and AFR Sensor Bank 2 is fine in the case of the VQ35DE but I think the flags on that byte probably should be:

Bit 5 - O2 Sensor Bank 2 Sensor 2
Bit 4 - O2 Sensor Bank 2 Sensor 1
Bit 1 - O2 Sensor Bank 1 Sensor 2
Bit 0 - O2 Sensor Bank 1 Sensor 1

There are the related OBD2 Mode 6 Supmask items to remove as well just in case so that if someone connects a scan tool, the tests don't appear at all.

I'd also be interested in defining the OBD2 Mode 1, and Mode 2 SupMasks and getting rid of any HO2B1S2 and HO2B2S2 references too. These should be it, all back-to-back shortly after where the ECU ID is in these ROMs (Edit: Looks like NissanDefs may already have a lot of this):

mGSM8ID - Control related to OBD
mGSTPI1 - PID that a mode 1 answer is possible
mGSTPI2 - PID that a mode 2 answer is possible
mGSTPI9 - The vehicles information type that it can respond
mGSTPID1 - PID that a mode 1 answer is possible
mGSTPID2 - PID that a mode 2 answer is possible

Then there are the Nissan DDL2 Stuff that we already have SupMasks for:

DDL2 CIDs:
111A - O2 Narrowband Bank 1 Sensor 2
111B - O2 Narrowband Bank 2 Sensor 2

DDL2 Switches:
1303 4 - HO2 B1S2 (rich/lean)
1303 5 - HO2 B2S2 (rich/lean)
130B 0 - HO2 B2S2 heater
130B 1 - HO2 B1S2 heater
130C 0 - Catalyst Readiness
130C 5 - HO2 Sensor Readiness
130C 6 - HO2 Heater Readiness

It's all pretty pointless I know but it would be cool to disable ALL the DDL2 and OBD2 responses relating to the S2 sensors.

I ended up updating my patch to just disable the DTCs, zero the B1S2 and B2S2 bits from the mO2S O2 sensor position byte and disable the related TIDs in the OBD2 Mode 6 SupMask. I'll just leave the rear O2 sensor OBD2 Mode 1, Nissan DDL2 logging parameters and switches to stay "supported" to save complexity.

Haven't had the chance to do any ROM modifying. My wife and I run an automotive merch company on top of our normal jobs and we were at Grid Life Alpine Horizon this last weekend. So this week and weekend I'll dedicate to working on the G35.