So I just noticed today after going to the meet that it took forever for my car to warm up to 84 degrees (its usually happy spot), and was really quick to come down again.
 
10 bob says its the thermostat stuck open, but thought i'd post here just in case anyone has any has other ideas on what it may be.
 
Will see if my mech can do an emergency thermostat swap tomorrow before the club run on sunday!

Yeah agree with the thermostat idea

make sure you get toyota genuine or you will have the same problem with a tridon.

I'm thinking thermostat also

You car may also be running very rich. Do you have an AFR reading anywhere?
 
Mine does that when I have a split vaccuum hose to the MAP sensor.

It does run a tad rich. I'll check the hoses tonight and the get the thermo stat changed tomorrow.

MR2QIK
You car may also be running very rich. Do you have an AFR reading anywhere? Mine does that when I have a split vaccuum hose to the MAP sensor.

If the hose is split to the map sensor it would get a lower reading and the motor would run lean, dangerously on boost, and will lead to melted pistons

Yes if you're on it dangerous. But I've noticed in my case at least, when the situation's arisen, it runs rich at cruising speeds. Not what I had expected, but was a reality. Or maybe I'm mistaken about where the vaccuum line was, but it kept happening around that area. Naturally I changed the hoses so the problem has been eliminated.
 
Just a quick thing to look out for before throwing money at it.
 
Another thought actually, did you tinker with the Power FC recently Dylan? If you deactivated the o2 sensor, then it'll likely run rich due at cruise. Unless mapped correctly in those areas (but I don't see many tunes other than Luans that run correctly with the o2 deactivated.

Well, yeh on an NA or when mani is under vacum you'd run rich, and then go lean when on boost. more boost=leaner, more vacum= richer.

Q:did you have this problem with the current motor, or the last one mr2qik?

Last one. That does explain it then, as I was never on boost on those times it happened (Sydney traffic driving). I monitor my AFR's quite frequently & check over a few areas before every wash (vaccuum lines, grounds, oil, coolant etc) so it's not often I'm caught out these days.