Well after replacing the engine coolant temperature sensor on my friend's 1990 Camry and seeing the recent threads on the 1UZ-FE, I decided to change it on my 2jzge 1993 sc300. My sensor was probably original and the new part is not too expensive so why not?
I used the following:
Duralast (Autozone) part number: SU4007
If you want to use Toyota:
OEM part number: 8942220010
Online: ~$42 - $52
Many Lexus/Toyota vehicles use the same coolant temperature sensor so it should be easy to find.
"The engine coolant temperature (ECT) sensor measures engine temperature by sensing water temperature. The ECM uses this information for determining the proper air/fuel mixture for all conditions." -via alldata.
If you know how to test it then refer to this:
Green colored harness located under the front intake runner going into the block.
doesn't mind me borrowing his pic from here: http://www.clublexus.com/forums/perf...-95-sc300.html
-Ratchet and extension(s)
-Deep socket 19mm (Make sure it fits over the harness side of the sensor and reaches the bolt. I tested it on the new sensor first.)
-Drain pan (coolant will pour out)
-(optional) Remove lower shield under the engine.
-(optional) Place drain pan under car because coolant will poor out once the sensor is removed. It may get messy so have some rags/paper towels ready to soak up excess coolant.
-(optional) If you have a container or pan that will fit under the sensor then it will be easier than removing the lower shield.
-Unplug harness from sensor. The area is pretty tight so I reached under with my right hand to press the release tab and used my left hand to pull on the harness. Came off easily once I got the technique down.
-Slip the deep socket 19mm over the sensor. Again, the area is pretty tight so it may take some wiggling around to get it on the bolt part. There were several times when I thought the socket was on the bolt, but it was only over the harness plug. Just keep pushing in and rotating the socket slowly until it catches since it is a snug fit.
-While removing the sensor, coolant will start pouring out. Have the new sensor out of the box and ready to install. You can also temporarily plug up the hole with your finger as you reach for the new sensor.
-Screw on the new sensor, tighten, and plug the harness back. Sorry I do not have the torque value, but just make sure you don't overtighten since the part is aluminum. Also, make sure it does not leak.
2/2/16 Edit: Tighten to 14 ft/lb
RESULTS and THOUGHTS
-As far as physical appearance, the old sensor did not look too bad after wiping some of the gunk off. It may have still worked fine.
-I have not noticed any significant performance gains in the last week since, but it seems to accelerate a bit easier. It can just be in my head though...
-I hope that it will improve my miles per gallon (mpg). I am still on the same tank so I will report back with any results.
-Here is my mpg log with brief descriptions. I'll let you guys decide if there are any differences after changing the sensor
Old sensor with some gunk
Old sensor after wiping off gunk
Reference threads from the 1UZ-FE community: