Coolant temp stuck at 300*

[FourG63GST]

I have been getting horrible gas milage (170-180/tank). I checked logger, had 21 CEL's for Coolant temp sensor.

A few months ago, checked ECU and it had leaky caps. Before I replaced them, the coolant temps would cycle and be crazy along with other sensors. After I replaced them they all stayed constant. I replaced the harnass for the coolant temp sensor that was ghetto rigged on there and tested the coolant temp sensor and the sensor itself is fine.

Coolant temp on the logger is now stuck between 284-300.1* at all times and I continue to get the CEL for Coolant Temp Sensor Sensor.

Car does NOT overheat whatsoever.

My question, now that the Coolant temp is high, will it not run in coldstart mode and richen it up, or will it still richen it up when the coolant temp is very high.

Could the leaky ecu caps have damaged something on the ECU that makes it record all these weird values? Is it something that can be fixed, or do I need a new ECU? The ECU seemed fine when we looked at it. (No brown gunk anywhere)

This is for a 92 GST. Thanks for any help.

Eric

 

[unior]

Could the leaky ecu caps have damaged something on the ECU that makes it record all these weird values?

probably!

see if you can borrow an ecu from a friend to troubleshoot - at least thats what I'd do

good luck

 

[Defiant]

tested the coolant temp sensor and the sensor itself is fine.

Coolant temp on the logger is now stuck between 284-300.1* at all times and I continue to get the CEL for Coolant Temp Sensor Sensor.

Car does NOT overheat whatsoever.

Replace the sensor.

 

[FourG63GST]

We tested the sensor and it was fine.

 

[unior]

well defiant and I both suggested troubleshooting ideas

try one k

 

[ECLIPSEESPILCE]

check for electrolisis in the coolant. Take a volt meter and put black to ground and red in the coolant in the radiator fill hole. readings should be under 300mv. Voltage in the coolant can cause this problem.

 

[FourG63GST]

well defiant and I both suggested troubleshooting ideas

try one k

I understand that. I will be trying another ECU this weekend to see if thats the problem. I already troubleshooted a bit and found the sensor to be okay.

I will also try out what the guy above this post said after swapping ECU's