how does the sub zero start assist work?
 

i have searched forever looking to find anything to tell me how it works, all i can find is how to test it and how to remove it. i know mazda had a tsb to remove it. but how exactly does it work? anyone? it is driving me nuts:scratch:

it is supposed to dump anti freeze into the combustion chamber to help with cold starts. It didn't work as designed so mazda ditched it

There's a temperature sensor on the engine and that tank on the right hand side of the engine bay. (The tank is near the back under the wiper motor on US spec cars... I don't think it's on RHD cars.) The tank is full of 90% Ethylene Glycol (Antifreeze) and 10% water.

When the sensor detects the engine is below freezing, it triggers the pump on that tank to put some of that solution into the intake... Sometimes ice can form inside the intake manifold when it's cold out. The antifreeze makes sure that doesn't happen.


To remove it, simply pull the tank out. Follow the hose from the tank to the intake, and remove that hose too. Cap off where the hose used to go.

I forget which sensor is associated with that system. There's so many temperature sensors on these engines... One behind the water pump... One in the thermostat housing... One in the oil pan...



You can use the tank for other purposes:

-Dump the antifreeze and fill with windshield cleaner. Hook it up to your windshield sprayers. Reroute the wiring for the windshield spray pump to the pump on this tank... Moves weight toward the center of the car.

-Fill with a light oil. Hook up a button to the pump and you have an instant smoke screen. James Bond, eat your heart out.

-Fill with water for water injection and decarbonization...

Actually, it has to be well below freezing to run the cold start. When you turn your key, you energize both the bendix to your starter and the cold-start pump. The cold-start pump grounds through the thermostatic switch in the oil pan, which is only closed below a certain very low temp that escapes me right now. If it's warm, the pump never grounds and doesn't run. It ONLY runs while you're cranking the engine.

Since water's incompressible, the little bit of glycol in your combustion chamber temporarily bumps the compression ratio up which is good for both cold engines and low-compression engines which can be hard to start.

I used to run mine to a switch and fill the reservoir with ATF for smokescreen/deflood duty.

antifreeze also doesn't combust at all resulting in fouled plugs, you get the idea which is why it has always been a useless system.

exactly what i was looking for, thank you:icon_tup: