. I am watching the temp trough the OBD2 and it does hit 180 once in a while. When it's really cold outside, stays in the 170s. I think all of the gauges on this car respond slow or are not quite accurate. Fuel takes 5 minutes to get to full after fill up and speedometer is is + - 2MPH when compared to the OBD2, so assuming the temp is a "best guess".
Those temps make me think like the others; it needs a new thermostat. No matter how cold it is outside, the temp should always get in the 180's and stay there.
Can you recommend an Android app that would give me the O2 sensor readings? The one that I currently use doesn't get them. Also, if you could explain open loop- closed loop a little more, that would help. What should the app say or am I just looking for voltage readings?
Sorry, but I know nothing about Android apps. The instructions for whatever you're using should explain how to find that, if it's capable. It should be under "system status" or something like that.
Regarding open/closed loop:
The O2 sensors need to be very hot to function, like 800°F. Until they get there, the ECU ignores the O2 sensors and uses default fueling curves, which are intentionally rich to avoid damaging the engine. This is called "open loop" operation. Once it goes into closed loop, the ECU relies on O2 sensor output to adjust fueling. Curious note: Most systems exit closed loop operation if the throttle is wide open. Prior to the advent of heated O2 sensors, it took a few minutes for them to get hot enough, sitting in the hot exhaust stream. By adding a heater, it takes 15 seconds or less, in my experience. This reduces emissions during that warm up period. Adding heaters happened somewhere in the early-90's, I think.
The ECU stores LTFT (Long Term Fuel Trim) values indefinitely, or until power is removed or it's reset using an OBD2 reader. Clearing the error codes, disconnecting the battery, or pulling the EFI fuse = a reset. It uses these values when it enters closed loop operation. If they ever get too high (>25%, as I mentioned earlier) the ECU sets an error code for "Bank X too lean", and turns on the check engine light.
There are also STFT's (Short Term Fuel Trim). These indicate what the ECU is doing in the very short term; like the last second, I think.
V6's have separate controls for each bank, so you'll see LTFT1 and LTFT2, for banks 1 & 2, respectively. Bank1 = rear, bank2 = front.
A malfunctioning sensor may give the ECU such a flaky signal that the ECU never goes into closed loop. This can be checked by monitoring the ECU with an OBD2 reader. A sensor like this, "walking wounded" as I like to say, doesn't always trip an error code. But if you see your engine never goes into closed loop, or goes in/out while you're driving, it could be a bad sensor.
Hope that helps.