No O2 voltage cycling...ever

[DarkhorseRS]

I’ve been logging my car with MMCD software, and am having some issues with the O2 sensor. At idle, even when fully warmed-up, the voltage just sits at 0.00V, sometimes flickering to 0.01V. At WOT, it will suddenly jump up to 0.76-0.80V, and just hold steady. I have a good log from today, but my cradle is being a turd and won’t hotsync right now. So the relevant info:

-My tps is at 99.6%
-RPMs from 3-6.5k
-O2 between .76-.80V
-Timing holds steady at 24 degrees
-My FTRL is pegged at 139%, my FTRM is around 100%, and my FTRH is around 111%
-Also my MPG is around 20 on the highway

I naturally assumed that it’s the O2 sensor (BOSCH w/ <3k on it), but I just replaced it today with an OEM and nothing changed at all. The plugs looked okay last time I looked at them, but that was a while ago. I reset the battery and ecu, and this changed nothing either. My MAF is unhacked, and my car is bone stock.

So now I just need some advice on where to go from here. Could this be a massive boost leak? Do I need to get a new fuel filter? Bad ground? Help?

 

[DarkhorseRS]

Not sure how I managed to double post this. Very sorry.

 

[DarkhorseRS]

No ideas on this? The car runs like garbage (shuddering and trying to stall out) until it gets warm since it is getting no O2 reading. How do I get it working?

 

[zippyshoe]

I would begin by performing a boost leak test. If you have a boost leak, then when you are idling, your intake will be in vacuum and you could be drawing in unmetered air (air entering your engine that your ECU is not aware of). If this happens, then you will tend to run lean because the ECU will not be supplying adequate fuel for this additional airflow into the engine.

 

[mitsugst97]

maybe i missed it, but have you changed your O2 sensor?

 

[CyberEye]

if your O2 is just sitting at 0.0V your o2 sensor is fubared. Time to get a new one. And figure out what killed the old one.

 

[DarkhorseRS]

As I said, that was my first assumption as well, but when I replaced it with a brand new OEM, nothing changed.

 

[Old Mitsu Tech]

O2 sensors can be tested by observing the voltage and introducing propane into the intake. They should go rich when the mix hits them. If you cannot get them to cycle that way or holding the car at 2,500 rpm then they are probably bad. If they respond then the problem lies elsewhere. Usually a lean o2 can be traced to vacuum leak, stopped up fuel filter and so on. Weak fuel pump can cause a lean o2. The trick is to isolate the cause of the problem and not the effect.

Good Luck