Miata/Exocet coolant re-route (ghetto version) acceptable water temp sensor position?

Hi guys

On the Exocet I did a ghetto coolant re-route. I just switched the water necks and added an extended coolant hose - I used to run an open thermostat (as a stop gap) and the coolant sensor in the middle of the extended hose. I've since put a thermostat in the rear water neck and put the temperature sensor for the ECU back on the front of the engine (on the front water neck). It seems to read a bit cooler than the engine is since I can feel the thermostat opening, is this an issue? It's not cold, cold - but definitely ~10* cooler.



 

I don't know the details of Miata coolant routing, but if the ECU sensor always has coolant flow to it (as in can't have coolant flow diverted from it by the engine thermostat) and is only 10F below the outlet at the rear of the engine, you can get away with it, even if it isn't ideal. If the ECU sensor isn't getting warm coolant until the thermostat opens, that can cause the engine to run badly below full operating temperature and if you drive it in the winter (unlikely, being an Exocet )

Lol - I just got done running errands in the Exocet. Not actually too bad (sunny day though, low 40s).

Unless I'm mistaken I'm pretty sure that part of the engine should always see coolant flow. I can just feel the thermostat side getting hot (it has a 190* thermostat) - so I know the reading is a bit low. I guess I can check what the maps doing. It's a MSPNP2 with a regular ol' miata 1.6 basemap. 

As long as it's consistent, it should be good. You just might have to tweak the cold running parameters to reflect what the ECU sees at normal temp.

In reply to Keith Tanner :

Sweet! Thanks GameboyRMH & Keith. It's so fun to drive - I need to get a phone mounted for a speedo or something. You just want to be sidways everywhere (very cold, very old r888s aren't helping anything). It's also geared hilariously since it's a 4.3 + 6 speed + 13" wheels. Lol - will probably be more sane when I finally swap in the 4.1. 

Exocets are never sane. They are a constant bad influence.

In reply to Keith Tanner :

This.

This is a thing I like to hear. 

 

Keith Tanner said:

Exocets are never sane. They are a constant bad influence.

I’ll vouch for this statement