O2 Problem - Please Help!

[4G63dsmpwr]

Well I bought a 90 AWD, and I recently setup my AFC2/logger...

No matter how much fuel I add/subtract my O2 readings will NOT move from the .78v-.80v area. I'm getting plenty of timing advance (20-25) and ZERO knock...

I have my AFC2 high throttle settings around +15% (around +20% at 6500RPM). This is where I see ZERO knock throughout the entire RPM band, and the most timing advance (21-25 degrees).

Now, if I subtract fuel (4-5%) from the above mentioned settings I start to see some knock (5-10 counts) and my timing advance drops alot (12-18).

No matter how much fuel I add (even maxed out the AFC at +50%) the O2s do not change. When I changed the settings to +50%, it was even popping, and clouds of black some were exiting the exhaust and everything.

So I've pretty much ruled out that these O2 readings are correct. At one point, when I raised the settings, my fuel trims dropped to 80%, from what I've read this means that the ECU is trying to take away fuel as much as it can..

First thought was bad O2 sensor, picked up a brand new one - same thing!

What could it be guys, open to all suggestions!? Maybe a bad ground, wiring or something?

Thanks alot for the space!

 

[fwdtsi]

Did you ever figure it out? I have a friend that has a newer maft and every time he leans it out it goes all the way to 81.2%....Its not a boost leak either..