OHC irregular temperature fluctuations
Background: 2010 Ranger 4.0L V6, VSS wire is tapped to the VT/OG wire on Pin #1 the center PCM plug on the firewall inside the engine bay.
Problem: The temperature is reading 5-8 degrees high. Furthermore, it is constantly fluctuating every several hundred yards by a degree or two. For example, the temperature outside might be 84F, but it will read 85, 86, 87, 90, 91, 87, 88, 89, 88, 89, 92, 89, 88, 89, etc. etc.
In terms of the temperature sensor, it is the correct one with the BU/WH, BU/YE wires. I originally mounted the temp sensor just inside the grill on the flat area just in front of the radiator but behind the decorative grill (as I did on my 2002 and other early 2000 Rangers). After just reading really high, I opted to relocate the temperature sensor so that is is ziptied directly to the decorative grill to ensure constant exposure to airflow (and minimize the image of heat from the engine).
I have gone through the old threads on this issue and what I am thinking is that either the tap to the VSS wire is not secure enough (although it is connected and seems secure from what I can tell), the temperature sensor itself is just bad and needs to be replaced, or the OHC computer is wacky. I could shift the VSS tap to the cruise control rather than the PCM module but I doubt this will solve the issue. All help/guidance greatly appreciated!