Temp guage goes to red on start up then simmers down to the middle after a few minutes. Your thoughts please

 

Sorry, I have to learn how to spell, I meant gauge, not guage.

 

I would say you have an issue with your temp prob. Try and get your hands on a Scan tool that you can read your coolant temp with to verify what you really are dealing with. You obviously shouldn't be pegging out a cool engine at start within minutes and then cooling down on the factory gauge.

 

If scanner not available an infrared point and click thermometer can verify temp in various areas outside the engine. Sounds like either bad connection, or need to change coolant temp sensor. On D1s they had two, a single wire that ran the guage and a two wire right beside it that drove the ECU. Not sure if that was updated in the D2, time to check the RAVE.... I did and there is just a single two wire sensor. I saw in the workshop manual under engine management, that location 10 was the coolant sensor, two wire. So the ECU reads that and drives the guage.

Now if the sensor is telling the ECU that temp is way off, the ECU might be trying to balance other issues, like mixture, timing, air pump operation, etc., so this could really screw up performace and mpg. Probably time to unplug and clean that connector on the temp sensor. Maybe replace sensor if further testing suggests.

On the earlier D1 the guage enjoyed a separate sensor, but pretty much functioned like an advanced idiot light. Normal, kinda hot, and shake & bake.