A coolant temperature reading that high would likely be from a bad ECT (engine coolant temperature) sensor. This sensor sends a signal to the computer so the computer can use the information to adjust fuel/air mixture, idle speed, ignition timing, and other things. According to Prodemand, an out of range ECT sensor reading will not necessarily set a trouble code. Replace the sensor. Its location is attached in the images. When you get the sensor, make sure you are getting the sensor that sends the signal to the computer, and not the one for the gauge. Yes, they are different sensors.
If that does not do it, then I would suspect failing spider injectors or possibly a failing fuel pump. A fuel pressure test and bleed down test would be the diagnostic procedure for that. I will lay it out for you if needed. Do the ECT sensor and let us know how that goes.
Wednesday, March 21st, 2018 AT 6:45 PM