When the coolant temperature is below about 40*F, my coolant temp reads wrong, which I think is screwing with my ability to tune the cold-start.

I've tried the numbers from brainiacs write up, and I've tried the numbers from DIY's site, and I think I tried a third set once from some other website, and I don't actually remember which numbers are in there right now.

Last week it got down to about -10*F, which left it at about 0*F in my garage, but the coolant temp still read 16*F. This error gets smaller as the temp in the garage rises, but it's pretty consistent day to day.

Is there some way to fix that problem? I'm using the stock mazda sensor. FWIW, the GM IAT sensor reads right on at those temps.

And these readings for cold starting are taken when the car's been sitting at least overnight, usually a couple days.

 

standalone is easy. r7 and r4 should both be installed. Gm defaults for the AIT and Rx7 defaults for the CLT. 2490 bias for each.

does your AIT match your CLT temps?

 

No. I'm sure I've used those numbers before, maybe one of those resistors is missing? I'll check it out when I get home.

 

Since you changed the values I would suggest taking the sensor out and testing the resistance value at three different temps. DIY should have a guide on how to do it.