this is why we need more LSJ table

[black06g85]

screw fuel my car runs on air only lol.

[mkriebs]

Tree huggers must be happy!

[black06g85]

They loved it, especially the big black clouds of flaming water vapor that came out the exhaust lol.

[CarsonTech]

Back from the dead!

I have a 2006 Ion Redline with 60 pound injectors, 3.0 pulley, K&N Typhoon CAI. I just installed a ZZP downpipe.

I have came across a situation where I had to unplug/not-use my rear o2 sensor anymore

I thought I could beat the problems people have been running into with catless cars and/or unplugged rear o2 sensor.

First, with my sensor unplugged, I just "disabled" COT by maxing the temp thresholds and zeroing out the COT Max and Min Adders. I also selected "no error reported" next to the bank 1 sensor 2 DTCs. But my commanded AFR still shows the symptoms of periodic checks (swinging rich around 13.x and then to 15.x)

So after that I disabled the "Catalyst Test". Yet, still, a check looks like it is still running, as I saw the commanded AFR going from 13.x to 15.x periodically.

I saw someone mention in this thread that they plugged the sensor back into the harness and strapped it up in the heat shield and that "fixed" their problem. So I plugged my sensor back in. I also saw where Bill mentioned, in a sticky, not to max out the Temp Thresholds, as "It appears there is a sanity check GM runs if you set the COT(cat over temp) thresholds to their max value" http://www.hptuners.com/forum/showthread.php?t=18181

With this "new" advice I followed, I was halfway successfully in stopping the weird commanded AFR. I no longer saw a Commanded AFR higher than what I set stoich to be, yay! So I was not seeing the 15.x commanded AFR anymore. BUT, I was still seeing the 13.x Commanded AFR, periodically, while cruising, just like before.

Now, after all of that, let me say this. I have a log of when I had an aftermarket catted downpipe, a week before I went this new route of not needing/wanting the functionality of the rear o2 . I unplugged the rear o2 sensor completely for this log, and used my normal tune as if the cat (meaning COT was functioning) and rear o2 was still in place. The log shows none of these tests happening! The Commanded AFR swinging from 13.x to 15.x did not appear anywhere in the log, and this log lasted about an hour with a lot of cruising on the interstate and a lot of city driving. I did get a Commanded AFR that changed due to PE and COT, but that was accounted for.

I don't know if that was due to the ECU not having enough cycles to notice that the o2 was unplugged or what, but it was great seeing that log, it gave me hope!

Tonight I am going to enter a value other than 0 in the COT Adder fields, like .01. I am thinking along the lines of Bill's thread about the Temp thresholds, maybe the the extremes of the allowed values for the COT fields do not disable or max out the values, but instead, just cause the checks to still happen, or a bug. I will post this log when I get home tonight.

If that doesn't work, I will unplug my rear o2 again as well, to better emulate the log where the tests looked like they wernt running.

I know to truly "fix" the problem, we would need some way to disable the "Rear o2 Test" like some of the other PCM/ECUs have. All we LSJ owners have is the ability to disable the Catalyst Test.

I posted a tune in this post of what I am going to try tonight, and a tune that I currently have loaded in my car that shows the periodical Commanded AFR of 13.x at cruising, if you are interested.

I am going to email support for HP Tuners tomorrow and see when and if they are going to add the ability to disable the Rear o2 Test for LSJ cars (P12 PCMs). I know they are supper busy with getting 2.4 ready and that adding this ability is not like adding a line of code, it would be extremely helpful as some other stated in this thread.

[CarsonTech]

Well, populating the COT Adder fields with something other than 0 didn't work. I guess the only thing left is wait and see if the HP Tuners team will add the ability to disable the Rear o2 Test.

I didn't get to disconnect the rear sensor from the connector on the harness, like in the log that didn't show the test symptoms, though. It is raining cats and dogs here now, so I will try that in the morning and log again.

I have a feeling that won't produce the results I want either. I feel the magical log I am trying to reproduce was just a coencidence.

I attached the "magical log" and the log I took tonight in hopes to replicate it, and their corresponding tunes. I also attached my Config and VCM Scanner config for my custom boost, AFR, and other custom PIDs.

In the "Magical Log", if you use my VCM Scanner config file, you will see my actual AFR, but in my latest log, you will not. I forgot to flip my switch on the AC Pressure wire for logging my wideband output. So my PID converted my actual AC Pressure voltage into AFR instead of my wideband's output voltage pipped through my AC Pressure wire. Atleast I got to enjoy my air conditioning!

Also, you will see around 1000 rpm and below, my commanded AFR is 13.1, thats normal, as I set that so I could idle comfortably above my injectors' min pulsewidth.

I would appreciate extra input or help, if you can provide any.

[CarsonTech]

Oops, went over the file limit cap on the last post. Attached to this one is the config for the logs and my VCM Scanner config for my custom pids.

[CarsonTech]

I found a combination that stopped the "rear o2 check" (periodic 13.2 commanded AFR during cruising) from running.

I unplugged the rear o2, made sure the COT Temp settings were stock, entered 0 in the COT Adder fields, set the B1S2 DTCs to "MIL on First Error" but unchecked the "SES Enable", and I also set the "Catalyst Test" to Enable.

My theory is the ECU can see the DTCs and that something is wrong with the sensor. The sensor isn't reporting anything at all, so the ECU doesn't perform any of tests.

Knowing I have some DTCs related to the rear o2 sensor doesn't bother me, especially since I don't see an SES light for them. I live around Greenville, SC and don't have any tests or checks to register a vehicle, so I don't give a damn about the DTCs, lol, as long as my Commanded AFR is pretictable!

So, what I have learned about the P12 ECU (atleast, in my 2006 Redline) is it seems like the more I try to hide the fact that the rear o2 sensor doesn't exist anymore, or to not use it anymore, the ECU puts more checks and test into place than if the o2 sensor was just simply unplugged and the ECU sees that and reports error codes (run on sentence??? LOL!)

I attached my tune and log for this. Ignore my recorded actual AFR, as I didnt pipe my wideband through the AC Pressure wire. You will just see my actual AC Pressure "converted"ninto AFR, lol.

I think the HP Tuners team may be working on getting us P12 users a way to disable the rear o2 test soon, if it's possiable with these ECUs. So users that have had the problem I had may not have to have any DTCs going on and still have no rear o2!

[lwrs10]

I found a combination that stopped the "rear o2 check" (periodic 13.2 commanded AFR during cruising) from running.

I unplugged the rear o2, made sure the COT Temp settings were stock, entered 0 in the COT Adder fields, set the B1S2 DTCs to "MIL on First Error" but unchecked the "SES Enable", and I also set the "Catalyst Test" to Enable.

My theory is the ECU can see the DTCs and that something is wrong with the sensor. The sensor isn't reporting anything at all, so the ECU doesn't perform any of tests.

Knowing I have some DTCs related to the rear o2 sensor doesn't bother me, especially since I don't see an SES light for them. I live around Greenville, SC and don't have any tests or checks to register a vehicle, so I don't give a damn about the DTCs, lol, as long as my Commanded AFR is pretictable!

So, what I have learned about the P12 ECU (atleast, in my 2006 Redline) is it seems like the more I try to hide the fact that the rear o2 sensor doesn't exist anymore, or to not use it anymore, the ECU puts more checks and test into place than if the o2 sensor was just simply unplugged and the ECU sees that and reports error codes (run on sentence??? LOL!)

I attached my tune and log for this. Ignore my recorded actual AFR, as I didnt pipe my wideband through the AC Pressure wire. You will just see my actual AC Pressure "converted"ninto AFR, lol.

I think the HP Tuners team may be working on getting us P12 users a way to disable the rear o2 test soon, if it's possiable with these ECUs. So users that have had the problem I had may not have to have any DTCs going on and still have no rear o2!

After a few days of fighting this exact same problem, this fixed it. THANK YOU. I called I dont know how many tuners and asked them....noone knew.

The only downside I have noticed with this method so far is gas mileage suffers. About 10mpg so far on a known road and conditions i drive everyday. I drive 100 miles of open interstate per day, so really good way to compare mileage. I normally get 36.5mpg with the cruise set at 73, last 2 days were 26mpg same conditions. It seems the computer is adding a tad of extra fuel since it knows that sensor has failed just in case of a cat overtemp.

I will try putting the O2 sensor back in after welding in an extra bung to I can run my wideband too. I will leave all the codes on but the catalyst efficiency code...I think its P0420.....and set it to SES enable no error reported. I hope this will work.