Another bad O2 Sensor??

[Zerocygnal]

My fuel trims are 140% for Low, Mid and High....my old and new O2 sensors do the same thing...? The ECU has been replaced and for the most part everything runs fine. A slightly rough idle is the only real problem I've had.

At idle the O2 will not cycle all the time, you have to tap the pedal to get it to start cycling.
At WOT it will sit at .90 and climb it's way down all the way to .25 but the knock is only reading 10 to 17 counts.(Bad enough). Any other ideas as to what is causing this? Bad ground...?

Stats:
94 Octane Sunoco
22psi on 14b
Typically had a .92 to .93 O2 @WOT with 0-8 counts of knock before

Here is the log...
This is a 3rd Gear pull

 

[halvorja]

Check out the ground connections on you exhaust. If you want, replace the ground wires with new ones and make sure you clean the connections.

See if that helps first. It's cheap and then you don't have to wonder.

Jake

 

[Zerocygnal]

I'll try that. I'm replacing the exhaust soon.

Thanks,
Ty


Anyone else have suggestions?

 

[pneumo]

That's some really low airflow counts for pushing 22 psi. I didn't see any MAF mods, stock injectors? No AFC? The airflow count fluctuates at high rpm. Did you pull the upper honeycomb?

 

[Zerocygnal]

It's odd...I often thought the same thing. When I was only running 18psi on factory IC pipes and intake pipe I could hit 1607hz and hold it until I let off the gas. Now that all of my pipes are 2.5" IC's and 3" intake it never reaches over 1450hz at 22psi. The honeycomb was removed a year ago, but I left the other one in. The injectors are stock, but they do well with what I am running. (amazingly)

I don't have a S-AFC yet unfortunately. I'm getting that with my AFPR, AN lines, fuel rail mod all at the same time. It's the next thing on my list actually...

Any ideas on the airflow count?

 

[hose101772]

maf overrun?

 

[Zerocygnal]

I have not researched MAF overrun very much but correct me if I am wrong. Is MAF overrun when the airflow exceeds 1607hz by quite a bit but it does not read past that numerical value?

 

[pneumo]

Sort of. Maf overrun is when the maf can't count all the air accurately. It usually happens at about 2200 Hz in the 1G maf. On a log it usually looks like a sharp decrease in the airflow # that lasts for only one or two samples. If you see it on a SAFC while running in line graph mode it looks like a downward spike.

Maf overrun can also look like airflow counts that seem to level off as the rpm goes up, but most loggers can't read any higher than 1607 Hz, or 1606, or 1605 depending on which logger is used. So if the airflow stops at 1607 that's just a limit in the logger.

So do you have a honeycomb in the upper chamber? If not, that could be your problem right there.

 

[Zerocygnal]

The only honeycomb I left intact was the largest chamber. If it's not there it creates turbulence and messes up the air count anyway, not to mention the uniform airflow.

Back to this O2 sensor. I've checked the connections, I think I'm going to try a known good o2 sensor my friend has. If the sensor itself is good....I'm going to have to track down whats causing those readings.