ea82 runs warm and high idle

[loyale1993]

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

 

 

[DaveT]

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.

[loyale1993]

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

[DaveT]

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.

[loyale1993]

Thanks DaveT I plan on checking it today.

[loyale1993]

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.

[DaveT]

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

[loyale1993]

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