Koyo runs too cold

[twofortyesecks]

I've replaced my radiator when it cracked with the Koyo one. It does a good job cooling, too good. When I'm on the freeway it drops in temp and then I get a check engine light. My friend said to put a piece of cardboard in front of it but with then rain or even car washes it'll get all soggy. I don't want to think about trying to pull cardboard out of the fins. Any suggestions? Is there some way to counter act this without just blocking off the radiator?

[toptechracing]

Put a good thermostat in the engine.

If the thermostat is working correctly then the engine won't be able to run that cold.

[Ubernoober]

Use plastic instead of cardboard. If you want to get real fancy, you can use a vinyl fabric with a zipper like big-rigs do. It will allow you to adjust cooling to the season.Unless you needed the extra cooling (high compression or turbo) a factory replacement would have done you just fine.

[InsanityInc]

Honestly, if you can afford the koyo, buy a better thermostat, ghetto rigging it will just cause more problems.

[jinsoku]

ill get you a brand new radiator and you could just ship the koyo to me...