Using my little OBDII bluetooth thing while driving I often get these crazy spikes of temp. I run in the 180-195 range usually, but sometimes I get a 3 second spike to like 220. I wanted to say I have a bad connection or something, but it happens exactly the same and frequently. Looks like this

 

Are your sure your fan clutch is working. Seems like it isn't and the electric fans have to kick on to try and save the day..

 

these spikes are 1-4 seconds long, I'm quite certain no fan goes from 215 to 195 in 2 seconds.

I'm wondering if maybe these are spikes of hot coolant that pass through the pressure thermostat, and then it closes back up?

 

Do you have a 4.6 ? I see similar behavior in mine, but at a lower overall Temp range. I'm going to replace the temp sensor and see if that changes anything.

 

Didn't get that from the data posted. Pockets of coolant at 213? I'd be more inclined to think pockets of air.
But I've been wrong before and will probably be wrong again. Just don't tell SWMBO

 

the man has a point

 

I have the ScanGauge to monitor realtime temps and had similar temps with the factory stat. You may want to purchase and install the gray 180* thermostat from British Parts of Utah. After that install, I pretty much sit at 188-194. If I'm off-roading up a bunch of mountains I may hit 204-207 with the AC on in the summer. Basically I think the spring starts to fail over time in the factory thermostat and the dash gauge is not sensitive enough to indicate the 20 degree temp changes. Only when the Rover is burning down on the the side of the highway it moves to red zone

 

I use the torque pro app also and found that it is reading the voltage about a volt below what an auto parts tester was reading. So maybe there is some buggery going on but yours is strange with the consistency.

 

IMO pockets of air in the cooling system or defective electrical sensors but I'd go with the former and re-bleed the cooling system.

 

Those thermostats are ****. They were **** when they came out of the factory and they continue to be ****. Bypass it and run a stant 180 super stat.