[redpoint5]

The most repeated myth I find on car forums is that a CAI will improve FE. There is no amount of reasoning with people because it's a religious topic.

Below is just part of a discussion I attempted to have on the jeepkj forum.

redpoint5 - Fuel injected engines routinely get better fuel economy at higher altitude for 2 reasons. The first is that the thinner air is easier to push through, which is very important in a vehicle that gave no consideration to aerodynamics. The second reason is that the throttle must be opened further to produce the same power as at sea-level. A wider-open throttle has less pumping losses. An open throttle allows the engine to breath more freely and the pistons have less vacuum to work against.

Pressing the throttle further doesn't mean the engine is "working harder". The throttle merely controls how much air to restrict to the engine. The ECU then injects an appropriate amount of fuel according to how much oxygen the engine has.

People who are most concerned with fuel economy will install a warm air intake (WAI) to reduce the density of air entering the engine. This reduces peak engine power, but it also forces the driver to open the throttle further for a given amount of power. This is a proven method to improve fuel economy in nearly any vehicle.

Check out this post at ecomodder.com. These guys are serious about getting every last mile out of a tank of gas and they do ABA testing to verify their results.

To sum up this post, if you want more power, install a cold-air intake, drive when it's cold out, and at sea-level. If you want better FUEL ECONOMY, install a warm-air intake, drive when it's warm out, and at elevation.

tjkj2002 - Boy you need to stop thinking everything you read on the internet is true or lay off the wacky weed.

You will get worse mpg's at higher altitude,known fact and has been known for over 70 years.You loose HP and higher altitude,again another known fact for over 70 years,which means your engine must work harder at higher altitude thus worse mpg's.For how much power you loose at high altitude is far greater then the advantage of driving through thinner air.

Where your throttle is has everything to do with how much gas you use as the TPS sends info to the PCM to match fuel flow for throttle position.The KJ already comes with a CAI right from the factory.

Your whole post and everything in it would leave,like myself,any ASE Master Tech rolling on the ground laughing and give most automotive engineers a heart attach.