Why is my lil' Na6 running nice ? - Coolant sensor broken !!

kazjim · Postby **kazjim** » Mon Aug 30, 2010 9:23 pm

Hey all, got a strange one for you ....

Most mornings my lilttle Na6 with Loch Stewart intake is a little 'lumpy' and usualy stalls as i get to the end of my street .... no biggie ..

But i noticed on the weekend that the coolant sensor on the thermo housing was cracked and sitting 'loose' in the nut ..

Took it out, disconnected the wire and took it for a drive ... it runs nice

so, i started it this morning (cold start in Gosford ... a bit chilly) and it didnt stall !

So, i ask you ... what has happened, and should i bother fixing it !

havnt taken it for a long drive yet, so dont know if fuelling / Fuel usage has been changed

Cheers

jerrah · Postby **jerrah** » Mon Aug 30, 2010 9:56 pm

Is it the front or the rear sensor that controls the fans?

kazjim · Postby **kazjim** » Mon Aug 30, 2010 10:05 pm

Hmmm, I"m guessing the front one ...

its small, one wire and vertical... sits above the thermo housing

so, it only controls the fans ?

No worries then

manga_blue · Postby **manga_blue** » Tue Aug 31, 2010 1:15 pm

I'm not sure what the setup is on the NA6 but on the NA8 the engine coolant termp sensor (ECT) feeds a temp signal to the ecu. The ecu uses this to determine mixtures and to control the fans (among other things). If you disconnect the sensor then the ecu falls back to an assumption that the engine is a bit coolish and sets things a bit rich. Maybe if your ECT sensor had been feeding bad signals then the ecu may have been doing all sorts of things wrong and the fallback position is better, although you could now find fuel economy is awful. For my car I'd get a new sensor asap - about $90 from Mazda (ouch), unless someone knows of an aftermarket alternative that works (usually around $10-20).

jerrah · Postby **jerrah** » Tue Aug 31, 2010 2:12 pm

NA6 has two sensors. One for the fans and one for the ECU. The fan sensor controls the fans directly without ECU involvement AFAIK?

jerrah · Postby **jerrah** » Tue Aug 31, 2010 4:53 pm

miataturbo.net seems to say the front one is the fan control. Are your fans still switching on?

kazjim · Postby **kazjim** » Tue Aug 31, 2010 9:51 pm

Cant really say, been too cold here and I've only made short trips .... will know tomorrow - off to work in the city ...

Cheers all

manga_blue · Postby **manga_blue** » Wed Sep 01, 2010 12:37 am

jerrah wrote:NA6 has two sensors. One for the fans and one for the ECU. The fan sensor controls the fans directly without ECU involvement AFAIK?

Yeah, my bad, just checked the NA6 service manual, Jerrah. You're right. For the NA6 this is just the fan switch. NA8 is very different.

kazjim · Postby **kazjim** » Wed Sep 01, 2010 9:43 pm

Well, funny story ....

So you know how today was a bit warmer ?
Guess who got stuck in traffic ?

It got a bit hot so hard-wired the fan switch to permanently on.....
saved the overheating i think, but I"ll be PM'ing MazdaTenFive any second now

Cheers all