Learn me: heat resistant plastic bags.

My Ecu on the nc has no plastic cover on it anymore (a cold air intake will do that.) 

so there are a few options. https://davefab.com/shop/mk3-nc-mx5-miata-ecu-cover-splash-guard/

this guy makes a bracket. I'm not paying him to make something I can do in the garage. But then I thought about a simpler option- a heat resistant plastic bag to keep the Ecu dry, should a radiator hose let loose. I don't have hood vents. 
i have the bottom engine bay cover on. So it's well protected from the elements, but not a radiator hose or radiator leak. 
what's a simple, cheap, durable plastic baggy? Ecu is probably 1ftx1ft?

edit: asked the chef BIL, he says the oven bags for cooking aren't durable at all. Basically one time use. 

https://www.amazon.com/Henry-BH200WB4559-Blueskin-Self-Adhesive-Waterproofing/dp/B00373PKGG

anyone used this stuff? It might protect the edges. Not sure if it would protect the molex plugs. 

Look for silicon sous vide bags.  Not sure on price, but it should be easy to find at least.

In reply to Mr_Asa :

Thanks. Those might be the ticket. They even come in fun colors. BIL thought I meant for food use, which is why they throw them away after one use (food contamination)

What about a conformal coating spray? It's used to seal control boards. I could hose down the Ecu edges and the ends of the Denso connectors to make it water tight and still look oem. 

The only problem I see is it might prevent future diagnostics at the connectors since it would, likely, prevent multimeter leads from making contact. 

Does the cold air intake actually make a difference in power output?

Just get some of those bags you cook turkeys in??  

Seriously though, I'd just get a piece of sheet metal and drill two holes:  one for the M8 stud on the left of the ECU and one for the right, or that ground stud.  Make a tent to cover your ecu connectors, and bend it so that water channels away and call it good.  Or just call it good as-is.

The ECU on my Subaru-converted Vanagon is wrapped in a heavy plastic bag with a ziptie closure. It's a little ghetto looking, but the ECU is sure a lot cleaner than the bag is. It's not a special bag, just a thicker-than-normal plastic unit. A gallon ziplock freezer bag would probably work. 

Most ECUs in the engine bay have a moderate level of waterproofing anyhow because their environment is not waterproof.

In reply to Stefan :

The AEM does, it puts the cone filter directly in the bumper opening. It's actually illegal in STR unless you move it behind the front bumper opening. The intake,  Along with full exhaust and header and a tune, produces a lot in the mid range. (For NA tuning). 
 

for consideration: https://www.mazdatalkforum.com/viewtopic.php?t=438&postdays=0&postorder=asc&start=60

This too provides some good reading on the subject. https://www.sacramentoareamiata.org/files/NC_Full_Exhaust_Tune.pdf

In reply to Keith Tanner :

Thanks. Was trying to go for a simple "5min" install, but also make it look less ghetto than a sammich bag

Tyler H said:

Just get some of those bags you cook turkeys in??  

 

 

Seriously though, I'd just get a piece of sheet metal and drill two holes:  one for the M8 stud on the left of the ECU and one for the right, or that ground stud.  Make a tent to cover your ecu connectors, and bend it so that water channels away and call it good.  Or just call it good as-is.

The oven bag is a thought, though it would be the silicon type, as that's more reusable. If I can find a black one I will. Though I doubt it. I just know how much those ecus go for online. I don't want to have to replace one. 
 

a metal bracket I can do, I just know how ocd I am when I make brackets, and this would cost me probably $50 to do it to the caliber I like. An oven bag is $5 for several. If I can seal it (for free) it'll look pretty.