servion

setup: turbo b18c with a low mileage water pump, a new PWR radiator with a large slim fan, a new thermostat, AEM EMS.

When driving constantly for more than 15-20 minutes or so, the needle on my temp gauge (in the stock gauge cluster) will start to rise. I can actually get quite high. If I get the car coasting and drop the RPM's for a while to let some cool air flow over the radiator, once I get the RPM's up a bit again to get the water flowing, I can get the temp gauge to drop down, sometimes back to normal. The point is that the gauge appears to act like the engine is indeed starting to overheat. Note that this is not triggered by spirited driving (i.e. boosting), but just by curising around town.

Here's where it gets strange: I had my AEM EMS hooked up the other day, and I had the privelege of being able to watch the temperatures. I was able to catch the car when the stock gauge was rising way above the normal level and I found that the coolant temp shown to the AEM EMS was normal. There was no difference between the readings from the AEM EMS between when the stock temp gauge was at normal operating temp location and when the stock temp gauge was nearly pegged (almost in the red).

Is it possible that both gauges are accurate? I dont think so, because the sensors for both readings are both on the side of the head, and they're very close to each other. The only difference that I can think of at this point is that the sensor for the stock temp gauge is 1 wire, while the one for the ECU has 2.

Any thoughts?

NJIN BUILDR

You may still have air in the system.Sensors have a tough time reading vapor.
The air gets in the pump and the pump spins in the air.No coolant flow.
Glenn