The DI trans is NOT computer controlled, it will shift into 4th gear even if the engine temp is 100*F, at least mine will.
The DII will not shift into 4th until the engine reaches temp, this is for emissions reasons, a cold engine requires more fuel than a warm one, increasing the RPM will warm up the engine faster so it will not shift into 4th until temp is reached.
the DI trans does not know any better.

If your cooling system has been neglected (most have been) you have some work ahead of you, but once all it sorted out you will be fine with the OEM set up.

Any radiator shop can add a row to a radiator for you, unless you have the plastic tanks.

Actually, the D2 transmission will shift into 4th gear regardless of engine temperature. However, the torque converter lockup solenoid will not engage until the engine is at normal operating temperature. I noticed this a few winters ago driving home from work. I drove the same roads to and from, and noticed my engine revs were higher on the drive home on a stretch or road close to work (engine cold). I thought it hadn't engaged fourth, and to test, shifted manually to third. Engine revs jumped even higher, so it had been in fourth gear already. I finally noticed on another stretch, that as soon as the temp gauge got to normal, while cruising at 50MPH. the RPMs dropped slightly. Not enough drop for a gear change, but I knew something happened with the transmission upon reaching open loop. I assumed torque converter lockup, as that is the only thing that can lower the RPMs by just a little at speeds of 50MPH.

Thank you for the correction.

Closed loop happens about a min after start up (I found out with the Ultra-Gauge) and has nothing to do with engine temp, it has to do with the O2's temp.
Something else I found out with that gauge is that everytime you coast you go back into open loop as well as everytime you accelerate hard.

Hi, everybody...I'm one of the bought it used guys...complete w/ the BLOWN HEAD GASKET...parts on the way...but, I'm wondering...while I'm waiting for the RAVE to download, what the little blow-off valve on the upper radiator hose is all about...it was blowing off...do I need to replace it, click it back together...or just eliminate it altogether?...

did your other post show up? under https://landroverforums.com/forum/di...acement-24726/

Yeah, my head gasket post, "posted"...I'm not much of a computer guy, so, I'm just now figuring out how to UNZIP RAVE...