93 Loyale 3AT.

 

I recently replaced the radiator because of leaks and engine running warm. The thermostat (Stant) was replaced about 20k miles ago. I still notice the temp gauge goes half way up sometimes a little more and sometimes a little less. I am also noticing high idle (1,100-1,200 rpm) at operating temperature. I will put the car in neutral and the idle will rev to about 2,000 rpm then slowly die down to around 1,500 rpm. I then shift back into drive and idle will go to around 900 rpm. The high idle returns once I accelerate and come to another stop.

 

After reading the forums I have checked the ECT by the thermostat housing with a multi-meter when the engine was cold with around 5ohms and then at operating temperature with a lower reading around 1 ohm (IIRC it's been a few days). Also, I don't think my electric fan is kicking on but I have yet to test the sensor attached to the radiator that operates the fan.

 

Do the 2 sensors work together or is the one on the radiator strictly for the fan only?

 

I have not tested the IAC yet but I plan on it now that I am thinking about it. Still I wouldn't think that would solve my warm running problem?

 

There is no CEL

 

 

The coolant temperature sensor screws in under the thermostat, on the side. It has 2 wires. It should change resistance by 1000s of ohms from cold to hot. I have had them fail intermittent, screw up the idle, and not cause a code. The fan is only controlled by the thermoswitch on the radiator.

I will retest with my meter on a higher setting. I didn't know the resistance was that high

CTS specifications from my 92 FSM:

 

Temp    Ohms

14 F    7K - 11.5K

68 F     2K - 3K

122F     700 - 1000

 

[K=1000]

 

Note:  The temperature gauge on the dash uses a separate 1 wire sensor.

Thanks DaveT I plan on checking it today.

I tested it today when the car was cooling down and I got values in the 500 and continued to climb steady. I tested it when the engine was cold and could not get a reading. So I warmed up the engine and now getting values erratic between 290 and 350. I'm thinking this ect is shot.

It should not be erratic.  The readings should be solid.  Maybe drift in the correct direction as things cool, but not erratic.

I put a new coolant temp sensor and it fixed the issue