milesg

05 GTO stock except for intake and exhaust/cats removed. After removing bank 1 o2 sensor for tuning i get no fuel trims at all so i have resorted to tuning OLSD. While in open loop i have disabled DFCO and PE but am having issues with inconsistent idle AFR readings i have tried to tweek the IVT gain table by making it 1.0 at operating temp with no changes, the idle will start out when i start the car regardless if its a cold or hot start and will be lean. Then once i drive around for a few minuets the idle afr will be 14.7 or a little richer but if i shut off and restart the trims will be back to 15-16.0 .Other than that all trims are within 1-2 and it runs fine. it seems odd to me that with only one o2 sensor connected the other one is still showing 450 ish volts on the scanner and its not even connected. I ran my G8 with one o2 and my wideband for 2 years with no issues in the same setup. shouldn't the scanner read 0v if its getting no signal from the o2 sensor? and wouldn't the constant 450 reading its getting throw off the trims if i was able to get into closed loop? I have no issue deleting the maf all together and running OLSD because it runs much better then my maf tune and within the next month i will have a cam hopefully turbo setup on the way. I just need to figure out the idle issue and thats why i am asking for help from you guys who im sure will know the issue right away.

You can see in the log i attached at the start of the drive i was in traffic and the trims where lean around 16.0 and by the end of the drive home i was rich near 14.0. this one is mild compared to some drives where im almost 17.0 and it will drop to 13.0 by the end.

Please help! in a week i will need to drive this car almost 5 hours to Florida for a school im going to every week so i need this car running good again.

gametech

iTrader: (1)

You should really just weld in another bung for the wideband and avoid the hassle of losing one bank of narrowband readings. Software can fix a lot, but the right hardware makes life a lot simpler.

2xLS1

iTrader: (25)

The PCM provides a bias voltage of 450mv to the O2 sensor signal wire so when it is unplugged that is the voltage you see. And you should do what the post above suggests.

milesg

I agree and will be welding another bung in this weekend but the issue I am having is the NB o2 are very rich compared to my WB due to LT headers and it makes tuning with stft difficult. I have herd of a way by adjusting switch points to make the NB match up but I'm not familiar with the procedure's . Or maybe move them further back from the headers? They are welded right behind the collectors right now.

gametech

iTrader: (1)

Odds are VERY good that the narrowband readings are more accurate than the wideband. The narrowbands are only accurate at stoich, but they do that very well. The wideband, on the other hand, can be poorly calibrated or subject to all sorts of installation problems.

milesg

I thought that as well but everyone I know that has the aem WB says it's spot in and it was accurate in my G8. Also the car ran poorly when I tuned off of stft and now runs much better with the OLSD tune and wideband. I am just not a fan of the inconsistent afr with the SD I may try and adjust the cylinder charge temp bias tables because it seems like that is the majority of the problem. Anyone tried that?

Darth_V8r

iTrader: (4)

Idle in open loop and track your average O2 mV readings. Make that your switching point for the lower airflows. Say for example you average 250 mV at idle and at 14.7. Make 250 the switch point. Then the computer will trim properly in closed loop.