I had a nice uneventful, mostly motorway 2 hour drive today. this evening however when I used the car again, I noticed that it was idling very high at about 1500 rpm's as opposed to the usual 850 approx. It seemed to be running fast and was pushing itself along quite happily with little or no encouragement from me. I switched the cruise on and off, going through the various options, just to see if it was acting up in any way. I stopped, switched off and started again, having checked the throttle return etc. which was fine,with no change and then, as I neared home (about 30 minutes driving altogether) I noticed the temperature gague was reading almost zero, but this began clinbing back up again towards its usual, almost 12 0 clock position, where it had been prior to dropping. Any thoughts? Air leak, split hose, breather, sticky TB? And would the temperature fluctuating be related. Thanks in advance.

96 x300 Sovereign, 91K 4.0L

 

My 3.2ltr did that temp thing when I first got the car.

Fuel economy went out the window, as did performance. Did not notice the idle bit, as I did not idle it, on the highway coming home and really just drove straight into the garage (mine) and renewed the thermostat.

All sweet.

I would do the thermostat first, as I reckon it is not doing what it should. They do work hard and fail after about 10 years or so, more often on the mighty V12.