Yes, since he did I have a question. You guys that have the PFC and the aftermarket sensor in the thermostat housing.(Like Rynberg) How much higher is the reading at the housing?

Thanks

 

I see between 10-15 degrees higher at the filler neck.

One other thing, the water temp at the throttle body upon shut down does rise about 10 degrees and then it decreases.

In contrast, the temp at the filler neck keeps going and going to 240 degrees. The only explanation I can think of for this is that the turbos coolant lines feed into the filler neck and so coolant is heated up by the turbos after shutdown. If your sensor is on the filler neck, the temp rises like crazy.

Hence, my auxiliary electric water pump that keeps water circulating until the filler neck temp drops below 200.

 

Disclaimer: the gauge I used for temps at the TB is an autometer and the gauge at the filler neck is a VDO so there could be errors in the values reported by respective gauges.

 

I am sure it's just heat soak. The tb colant lines don't have a large mass of metal present to retain heat in the sensor as the other locations do. I do see indicated temps in the tb line drop quickly with the engine off, but as soon as you start the engine and circulate coolant you'll see the temps come back up to "real time" immediately.

 

poman, I hope so. My fans come on at 225 on my Delfi water temp gauge. Low temp fans come on (with stock thermosensor) at 221. That would be a +4 vs the stock temp sensor. I still need to do the Miata thermoswitch.

 

The t-stat housing sensor reads higher most of the time. Under pure cruise conditions on the highway, they will read identically. Under hard driving or stop-and-go, I've seen as much as 15F degree difference (PFC reads cooler). This is to be expected as the coolant SHOULD be hotter leaving the engine as it is absorbing the heat.

The t-stat housing location is the worst-case reading in the cooling system.

 

Hmm... I'm starting to wonder how consistent the manufacturing specs on the stock sensors are.

 

Just thank your lucky stars this is not an American car. I've seen insane variations on all kinds of things on those cars...almost like they just didn't care *gasp*