Was out on a brief drive this afternoon to log some data via my consult cable using ecu-talk. I do this every week or so in different weather conditions to check for problems.
I had driven for about 40 minutes when I pulled into a service station to refuel. A look at the data at this point (while the turbo timer kicked in) showed me everything was fine, with temps not getting above 85 deg C.
After refueling and paying the petrol man (a total of about 5 minutes), I started the car again and quickly noticed the ecu-talk Water Temp gauge flashing, indicating the temp had exceeded the set value of I think 95 deg C. Very interesting I thought because as I was looking at the ecu-talk gauge, it was indicating 92 degrees but dropping very quickly i.e. within seconds.
So I drove down the road to my house and got all the data in to Excel. This is what I discovered:
At the point of turning off the car, temp was 85 deg C
~5 mins later upon restarting the car, the temp was indicated as102
A fraction of a second later it was 101
A fraction of a second later it was 100
and so on until 5 to 10 seconds later it was low 90s
A minute later is 90
As I started moving it dropped below 90 and once up to 70kph it dropped very quickly to below 80.
Can anyone explain this? Any guidance appreciated. Cheers