I have myself a '94 Sprite and I don't think I've ever seen it read Normal on the Water Temp Gauge.
A typical reading is very low on the gauge. [C.I...N.....H] for example. If I toodle around town (I don't live near town so not often) it will go up to [C...I.N.....H] a bit below Normal however as soon as I get to a 40+ stretch of road within minutes it's back down to very cold on the gauge.
I've done some research and I gather it's most probably the Inlet Manifold Temp Sensor on the under-right side. Now, should I go ahead and replace the part(?), clean it out first(?) or is it not a problem altogether?
I'm sure it should read Normal, Normal is Normal and therefore I want to get to the bottom of this. Can someone with experience in this help me in conjunction with Sprocket's post (below).
I will be investigating and cleaning out the Sensors connections tomorrow as long as I can get to it without disconnecting the Inlet Manifold. You may suggest an easy way to remove it the Inlet Manifold so I can get to it but have heard it's possible to get to it from underneath.
Many thanks everyone.
Sam (Minify)
Sprocket's post on the matter:
The coolant temp sensor is the black sensor located in the inlet manifold. It can be found underneath at the right side of the manifold as you stand at the front of the car.
The coolant temperature sensor works on the same principle as the air temperature sensor, where by as the temperature falls the resistance rises or vica versa. Problems arise when this sensor reads out again for the same reasons as the air sensor. This has a more dramatic effect on the fueling of the engine. If its so far out the ECU may never leave the cold start and warm up programs wich are open loop control where the signal from the oxygen sensor is almost ignored. Again this sensor will usualy read out low. A permenantly rich condition will result. This sensor is connected directly to the ECU and then the ECU provides a signal to the Temp gauge on the dash. The gauge should read not quite mid way, just a little below the white line when the engine is warm. If it reads any different then there is a problem with the engine controlling the temperature. Or the sensor is faulty. On that note it is worth while checking the plug connectors as these can suffer contact corossion. This sensor can only be acurately checked with the diagnostic and a calibrated thermometer. If there is any doubt and you are unable to have a diagnostic done then I would advise replacement but thats only if you are suffering a rich condition and the temp gauge reads below and never anywhere near the mid white line, not above as this would probibly be a cooling system fault.
Again if this sensor is faulty and causes an over rich mixture for long periods, the Oxygen sensor will usualy fail too, as discused above in the air sensor section.
It also may be worth noting that if the thermostatic control is not working correctly on the cooling system that both a hot and cold condition can result so it is in your best interest to fault find this first. For instance if the cooling system fault causes cooler engine temperatures then the ECU will see this as if the engine is still warming up and stay in cold start.
Here is the sensor removed from the manifold, it differes some what from the ones used on the carb engines.
And here is its location on the underside of the manifold in line with the water heating pipes( this picture is taken with the manifold removed and upside down)
Edited by Minify, 17 January 2012 - 12:20 AM.
