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Old 01-21-2013, 04:02 PM   #5
Focus Rookie
Join Date: Jan 2013
Fan#: 108520
Location: Portland, OR
What I Drive: 2003 Blue ZX3

Posts: 19
FF Reputation: 1 rycodge Good Standing Member
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Major update! I believe I have this one figured out.

One thing I've noticed is the engine idle and rpm behaves exactly the same if the car is cold or normal running temperature. This lead me to test the thermostat...

So I put the car into diagnostic mode on lunch today and the engine temp never climbs above 130F!!!. The upper coolant hose is always warm and you can feel the water flowing. Its been hovering around 32F outside, the radiator fans never kick in and the radiator is cold to the touch.

The heater gets warm, warm enough to properly warm the car, but its not piping hot either now that I think about it.

For what its worth I did have a bad iac valve. The replacement brought the revs down but the failed thermostat is keeping the engine in warm up mode. Gas mileage has also been terrible confirming the stuck open thermostat.
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