Okay this has been bothering me for a while and I've searched to no avail.
It's an S5 N/A:
My gauge for coolant temp never goes past the two little marks on the bottom.
Is this TOO cold?
Also my AFC tells me a different RPM than what the Stocker gives me. They remain close at low RPM's but climbing the AFC gets ahead of the stock tach... Which should I trust in your opinion?

 

Someday you might see if there is a thermostat installed or if someone left it out. Then again, I'm not familiar with series five gauges, only series four. And while there, see if it's a 180* thermostat or not. Should be imho.

 

When I rebuilt it a month ago, I made sure to replace the t-stat w/ the Oem one...
forgot to mentioned this

 

The OEM speedo is directly linked to the transmission so it should be pretty accurate. I wouldn't expect that much accuracy from the AFC.

You may have a busted gauge or maybe your are just experiencing over-cooling? Wouldn't surprise since the gauge basicly has 3 positions.

 

Ok. But, I've been buying what I THOUGHT were OEM thermostats from Mazdatrix, and low and behold they're 160* thermostats. I had to go buy a aftermarket one from Autozone for 180*. Well, I guess I could have gone to the Mazda dealership and paid some infalted bullshit price instead. Just some FYI.

I'm inclined to go with the SAFC tach.

 

He's talking about the tach, not speedo. I'd trust the AFC over the stock tach.

 

Depending who installed the AFC... Check the harness of the AFC, (does everything else on the AFC work accurately?), Check the connection of your tachometer system. Den report back promptly.

 

Damn, you just beat me to that.

And yes, he's the one who taught me that :-P

 

Oh well I just woke up...
I installed the AFC myself. I think I'm mk w/ soldering.
I'm POSITIVE the T-Stat is OEM... Got it from Racing Beat. All they sell is OEM
Mazdatrix even tells you they sell Stant sometimes, gotta call em for the oem.
About the tach, I always tell myself "the stock is accurate because it's STOCK, BUT the AFC is hooked directly to the ECU... AHH! *ripping hair out*

But really it's no biggy you guys, just something that bothers me and wanted some opinions

 

S5 coolant gauge only has 3 steps. cold normal meltdown.