I got a problem with the car warming up when it's cold outside. When the car is at idle long enough the temp gauge will rise. But as I start driving the temp gauge starts going down. So it doesn't hold a constant temp when the temp outside is around 50 degrees or lower. This is my 3rd motor in the car. Each motor had a different thermostat. Same problems though. The radiator is new and the cooling system was flushed prior to the new radiator. Is there anything else but the thermostat that can cause my problem? Need help here. Thanks

 

Most likely a stuck open thermostat, had a prob like that in my teg, replaced the Thermostat and it is fine now.

 

So you are not over heating, right? When you start driving the temp should go down a little, thats normal. Does it drop all the way down on the cold side? Do you have an after market gauge? Or is it stock cluster?

 

it's stock cluster. The needle drops all the way down to the cold side, but the engine stays warm enough that vtec still kicks in. The heater works, but it's not as warm as it should be. My car doen't overheat (or at least the temperature says its not). But yea I'm going to replace the thermostat now, I was just wondering if anything else can cause this. Another suggestion was the ECU. I have a B16A2 with a JDM p73 ECU. I don't know if that has anything to do with it. But I am open to other suggestions.

 

go get an oem thermostat from the dealer, do not use an aftermarket thermostat

 

Same problem, 3 motors, 3 different thermostats..... hmmm, this is a toughie, did you think that maybe it's not the thermostat and is a problem with the car?