I have a 1999 F150 with the 4.6 i want to put a cold air intake on but do i need a custom tune before i do so? if i dont get the custom tune and still put the cold air intake on will it cause my engine to run rich or lean?
they usually cause a bigger problem than you need.
No, because putting a cold air intake on will do nothing at all. Your truck already has a cold air intake that is quieter and more efficient than any aftermarket kit you buy. Cold air intakes are one of the biggest wastes of money performance-wise there are. They are just pure hype. Most people never run their truck in an RPM range where intake restriction would even be a factor.
I'm not aware of any need to get a specific tune for a cold air intake. Since the nature of AIR can be COLD or WARM - even HOT, I'm sure the computer will figure all that out on its own. Your intake should consist of a MAS (Mass Airflow Sensor) which measures the amount of air the engine is ingesting. Based on that information the computer will set the amount of fuel injected into the engine. As the engine burns the fuel / air mixture, some unburnt oxygen will go out the exhaust. The O2 sensor measures the amount of unburnt oxygen and makes further refinements to the fuel / air mixture to optimize fuel economy AND pollution control. So I don't think your engine will run Rich OR Lean. Should be business as usual. Good luck. :)
