NOW I have PFC in my FD now, When I start my car this afternoon, I wait about 10 min, From commander I can see the water temp already pass 80 C, but my stock gauge did not move a bit. is this normal. I know stock termo will open at 85+,
I hope this wont be a big problem

 

I heared the stock temp wont move unless it hits 100 something C.

 

The OEM gauge doesn't really move past halfway (3/4 MAX) unless your car's about to overheat. And when you realize, your car's most likely already overheated.

Get an aftermarket water temp gauge.

 

According to my PFC commander my water temp is normally 87 C when warmed up and I've seen it as high as 105 C on very hot days with hard driving. What you're seeing is normal.

 

The stock gauge takes the temperature from another sensor. Diagnose this sensor, as this is the sender to the gauge.

 

I think the sensor on the back of the thermostat housing is for the PFC and the one next to the oil sending unit is the one for the stok gauge.