To finish this off with the outcome, so that it has some relevance in searches.

I put the stock sensor back in the stock location in the head and moved the aftermarket one to the water neck. This solved the problem instantly.

So the lesson is to leave the stock sensors alone and just add the other ones elsewhere.

 

LOL!!!!!!!!!

I've watching my gauges more closely during warm up laterly since your posting. Stock gauge at 1/4 while Autometer still below 100!

FYI you'll notice the water temp goes to 160-165 and levels off there for a few miles then starts climbing to normal cruising temp of 180-185...........it's just the oil warming up!!!!!!!

Oil removes 1/3 of the engine heat and ONLY thing that cools the bearings!!!!!! I just learned this a few weeks ago.

My sender using a 29/32 drill bit and 1/4" NPT tap where the bleeder screw used to be.

 

Autometer supplied two fittings like that but I just put the sender straight into the neck like that.

I used a 10mm 1.25TP tap. looks the same as yours.

 

That's strange. I've had my sensor disconnected(the one wire that goes to the guage)with no CEL's. I always thought that sensor was completely seperate from the ECU and the two-wire sensor was the one that supplied information to the ECU.
__________________
Best Car Insurance | Auto Protection Today | FREE Trade-In Quote

 

thats how it is on my crx boost.

the sensor under the dist is for the gauges only. the engine sensor is on the back of the block.

 

^ Not on my ef hatch. The sensor on the back of the block is the fan switch. The sensor for the ecu is a 2 wire sensor in the head under the distributor next to the one wire sensor for the water temp gauge. I also ran with my stock temp gauge sensor unpluged with no problems. It should not throw any codes.