I just put in an air duct house from Home Depot in my 89 Mazda 626 with a cone air filter. While it did wonders for my throttle response and smoothed out my acceleration, I noticed that my engine no longer heats up to the middle of the indicator on my instrument cluster. I know a car uses more fuel while warming up, so is this going to bog down my mileage? My question also has regards to my 97 maxima as i thought to install a pipe also in order to achieve a cold air pathway.

Thanks

 

cooler engine (but not cold) is good...
my car is much faster when the temperature outside is cold...my engine is already siiting there for 10 minutes..but the temp gauge stays lower than usual...
I am not complaining....
=]

 

I'm not sure how a pipe that directs air to the cone filter can possibly affect engine temperature that much. Even on a freezing day, the engine should reach normal operating temperature in under 10 minutes.

You are right in that you use less gas when the engine is warmed up already. The optimal temperature for the engine to operate is between 180 and 190F I think, and if you running lower than that, you'll waste gas. If your engine isn't warming up properly, the first I would check is the thermostat. It could be stuck in the "open" position.