TheRealDirtyDan

Hey guys I’m hoping to get some help. After reading MrFred’s post on tapping the wideband signal into the rear o2 adc to log AFRs, I completed it on my car but had no success and now I’ve been having some issues with the car. The car starts idling at 3,000 and slowly creeps to 3500. My zeitronix zt-2 lcd is now not working either. I will go step by step on exactly what I did to hopefully allow you guys to diagnose better.

1. Disconnect rear O2 sensor plug under the seat
2. De-pinned the signal wire on the O2 sensor side so I could leave the wiring harness side plug original.
3. Taped off the signal wire I de-pinned (it’s the blue wire on the O2 side, turns into white wire on harness / ECU side) and reconnected the plug. So the O2 sensor was connected to allow the heater circuit, except signal wire wasn’t connected.
4. Unplugged plug “C” on the ECU
5. Took the wideband linear output from the zt-2 (white wire) and tapped it into pin #73 according to the USDM evo IX Pinout(also a white wire). I double and triple checked to make sure I had the right wire and I did.
6. Reconnected Plug “C”
7. Turned on the car and immediately knew something was wrong when idle shot up to 3k - 3.5k, so turned it off (I also noticed the zt-2 lcd wasn’t on)
8. Disconnected negative and positive from battery for 5 minutes hoping to reset ECU.
9. Reconnected battery and then made sure to get on the E85 map (dual map tuned) and turned the car on but still doing the same thing.
10. Checked to make sure zt-2 box was getting power, and it is, but for some reason the lcd still isn’t working.
11. Disconnected the wideband output from pin 73 and disconnected the battery again for 5 minutes, but no luck.

I still have not connected the signal wire from the rear o2 back into the plug but I don’t think that would change anything would it?

at this point I’m thinking I popped something since the zt2 screen isn’t working and the car is acting weird so maybe I also popped something in the ECU?

any ideas guys?

TheRealDirtyDan

Update: disconnected the wideband output from pin 73, and reconnected the OEM rear o2 along with the OEM signal wire and the car is idling fine. This doesn’t make sense to me as the tephra v7 rom I’m using states that the o2 simulator is turned on, so that should have allowed the car to still run when the rear o2 was disconnected right?

What gives?

Biggiesacks

i would put a meter on that linear output wire from the ZT2 and make sure its outputting the voltage you are expecting based on the serial output from the ZT-2. What i mean by that is use their graph to make sure the outputted voltage matches with the numbers you are seeing in the zeitronix logging software. That way you know that the ZT2 is working properly and outputting what you think it should be.

As far as i know, with everything configured properly in V7 you should be able to completely disconnect your rear 02 and not have any problems. I have anyway but I have an 8. I too have the output from my ZT-2 going into my rear 02 input, only my zt-2 is so old that its a non linear output lol.

TheRealDirtyDan

ok I did this and it seems ok. it was fluctuating around 2.3V at idle, which using their formula "2*V+9.6" means it was fluctuating around 14.3AFR, so I'm assuming it was just jumping up and down from the 14.7 target at idle.

ive been thinking about it some more about the car idling / acting normal with the rear o2 plugged back in. I'm guessing some type of mod isn't in the ROM like I think it should be. I see "Rear 02 Heater Patch" and the hex in it is "4A0B" ( is this correct?)
also under "Tephra Mod Options" I see "Enable Rear O2 Simulator" and its down as "1" meaning its enabled.

are these 2 things the only options I need to completely eliminate the rear O2, or am I missing something? is there a periphery bits I should look for in my ROM?

TheRealDirtyDan

Biggie, you mind showing me your ROM so I can compare your options to mine? would help a lot!

RightSaid fred

Still got the cat?

TheRealDirtyDan

no sir, straight pipe

Biggiesacks

yah sure ill post it up later today. On top of the tephramod options for the rear 02 simulator there is also a section called "Rear 02 Heater Disable" that has 2 different settings that need to be toggled. The "Rear 02 heater patch" and "Heater Cel"

TheRealDirtyDan

Biggiesacks

grab the phenom XML pack from the beginning of the V7 thread, its the XML's for ecuflash that you need.

TheRealDirtyDan

ok i downloaded the phenem pack, replaced the tephra v7 xml in the evo folder with the tephra v7 in phenem's pack. Lots of new features available to dabble with... so now my question is this

if i open my ROM with the phenem XML options now available, are all these new tables that i havent touched also going to get saved with the ROM and alter the tune? My car isnt tuned by PSI mode, yet one of the Phenem options allows to tune by PSI, and its enabled by default. If i save my ROM without altering anything, will these new options also get saved with the tune and alter the tune / car?

Biggiesacks

the XML's don't change any of the settings in the rom. They only show you more or less of whats there. The XML itself only has the locations (addresses) of data, and how it should be interpreted.

TheRealDirtyDan

thats good.

so update: retraced my steps, and made sure the car was operating well again. Then literally re-did the process again and it worked great. I must have crossed a wire somewhere the first time.

then did MrFreds AFR logging through ECU mod and that went great as well.

thanks for sticking around and tossing ideas Biggie!

Biggiesacks

cool, glad you got it working. You should also look into setting up the AFR out of range safety features Tephramod v7 has built in if you haven't already.

TheRealDirtyDan

Oh great idea, I’ll look into it today. Thanks!