• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Removing rear O2 sensor on 01-newer PCMs -- Things you should know

is yours still running the tests and over fueling? if so, why not change the bin to one thats supported? all it needs is a security learn, maybe a crank learn.
 


if you like i have one downloaded already i can make the changes if you want, then email it to you. if you still cant see it when you open the bin in TT id say the issue is in your tiny tuner set up with the database.

but either way the changes are made and should stop the testing. all you have to do is load your tune to this bin file.
 


Well I just got bit by this over the weekend. Fixed a few things on the car and at the same time installed my new wideband in my catless DP.

Having seen this thread in the past, I left the rear o2 in when I installed the pipe months ago and it was fine. So now I replace the rear o2 with the WB, but leave the rear o2 hooked up and tucked up over the heat shield.
Start doing my maf tuning and seeing my LTFT going to +16.4 and I'm thinking WTF!

Replace the WB with the rear o2 and it's happy again.

So either I need to add an extra bung for the WB and let the stock one be, or figure something out in the programming.

I have the right stock .bin for my car from Bill's dropbox. I opened it up with Tinytuner and disabled the diagnostic, but I can't do anything with it in HPT because the VIN/serial isn't licensed. I changed the VIN in Tinytuner, but it won't change the "serial number".
 
Last edited:
I just bought an 02 Emulator/Simulator from ZZP. From what the ZZP tech guys say you cant just use any o2 sim. It needs to have the correct resistor it in that our PCM likes so it will report back the right MV then letting the cat test to complete. I just got it so Ill pop it on and report back.
 
Uno99 said:
I just bought an 02 Emulator/Simulator from ZZP. From what the ZZP tech guys say you cant just use any o2 sim. It needs to have the correct resistor it in that our PCM likes so it will report back the right MV then letting the cat test to complete. I just got it so Ill pop it on and report back.
Click to expand...
If you bothered to read this thread you would know that those do not work, your car will still dump fuel.
Trannyman95 said:
An 02 sim does not fix this problem. I know this because the car I had trouble with already had one on it that works fine and removing it made no changes and the condition actually lessoned with nothing in place
Click to expand...
 
FWIW, I did what Scotty did posted on the last page and put my setting to -285 (or whatever it was) and my LTFT went to +16 as well. BTW, my trims were disabled before and I enabled them a few weeks ago to see what they were at. I did some fueling changes and on Sunday changed the rear cat delete setting. (I haven't had a cat for a long time) Right after i did it my trims went to +16 at times and then leveled out, then went back to +16.

I talked to another tuner (who doesn't post much on here anymore) and he said to change it to 140 in the first setting rather than -285. Reason being that -285 is -481 in Fahrenheit. That's WAY out of scope for the table and basically does nothing.

After changing it to 140 in the setting (284 F) the trims do not go to +16 anymore and seems to be normal.

I guess since it's -285 in the table that basically the rear cat test will run all the time constantly because it doesn't know what to do.

Anyways. If you want you can try that and see what happens.

Edit - I need to look at tiny tuner but my setup in the tuner might be in Fahrenheit and not Celsius and that's why it was throwing it off. So.. look at and see how it's setup (C or F) before changing the setting.
 
I doubt it's going to go anywhere, but I emailed the guys at HPT about disabling the test. Also asked if there was a way to flash a .bin with the test disabled even though it's not licensed with my mvpi.

[EDIT]
I actually got an answer from HPT. I'm going to provide them with two .bin's, one with the test enabled and one with it off and they'll add it to the work queue for the next version! Awesome!
 
Last edited:


Slick2500 said:
If you bothered to read this thread you would know that those do not work, your car will still dump fuel.
Click to expand...
Well good googley moogley Slick......I did read it a few time actually. I was simply trying to add what I was told by the ZZP rep. So sorry. I actually mentioned this thread and he assured me that this was an issue awhile back but their O2 sim would work. When I was on the fence he followed up the the the "it needs a specific resistor so the pcm sees the right mv" line which must be BS. He got me.

I popped the sim on today and only scanned for a bit. The 02 code is gone but as you all stated the test does not complete.
 
On 2004 Grand Prix's..... anyone figured out how to remove the cat test?
32 mpg one second followed by 21-22mpg for several seconds with no change in driving, road level, wind, etc.... just a sudden 30%+ drop in fuel economy sucks and I'm hoping to get it figured out before the Magnaflow is plugged like the two good used factory cat's I had installed over the past several weeks.
I've checked for vacuum leaks, etc and everything is checking out good except the when the ecm runs the cat test everything goes wonkers (fuel trims, etc..).
Full tune up, new AC Delco o2 sensors, cleaned MAF, fresh topswapped engine with all new gaskets, etc... Previous owner had two engines put holes in the block over the past 200 miles he owned it and I'm not looking to go through the same.
I've changed the ICM, and next move is to try a used replacement ecm from another 04 Comp G.
 
IIRC, 2004 and 2005 are different..... at least ZZP used to state that 2004 Comp G owners had to use 2004 Comp G hardware/software as it was different than 2005, or has a way to interchange hardware or software been figured out.
 


Have there been any updates in the latest HP-Tuners software to allow the test to be removed?? I purchased a brand new HP-Tuners Pro software & license in April.
 
I'm in the same boat as you. I had to have Eddy convert my HPT tune into a bin (?) so he could edit it through TinyTuner.
 
You must log in or register to reply here.
Back
Top