Probably a dumb question but I keep seeing guys say you need a tune after putting an intake on otherwise your engine will run lean. I don't understand how this happens. You have the mass airflow sensor that will correct the fuel mapping for the extra air preventing the lean scenario. If I'm wrong please feel free to correct me.

 

It's because the amount of air flow with a CAI exceeds the parameters of the program. You are correct that there is an adjustment made by the reading at the MAF but it has limitations. There is a max and minimum in the table. The custom program redifines those parameters.

The lean condition is primarily with the 2004s and 2005s that came from the factory in a near lean condition. However, there have been a few later models that have thrown a CEL. It isn't just that, your PCM was programmed for the stock intake, and unless you have a custom program redefining the parametrs, you are not getting but maybe 50% of the benefit from a CAI. To me, as much as the CAIs cost, it's a waste of money without a custom tune.

With a custom tune, it's been shown on a dyno that you get almost as good results with the home intake mod.

 

the 3 valve motors have electonics taht are very sensitive to air inlet changes hence the lean issues



a 3 valve motor with a CAI and a custom tune for the mods on the engine usually get better mileage as well (depedning on driving habits)

the 2 valve motors aren't as prone to running lean but once a gain a custom tune for the mods allows your motor to maximize them

 

Yep, I should have been more specific. The lean issues are with the 5.4 3v. However, my comments concerning power benefit from CAIs applies to all.

 

agreed, however you worded it much nicer in your post than I did

 

Thanks for clearing that up everyone.

So on another note, would changing said parameters void warranty or make it hard for the dealer to trouble shoot problems when they hook up their computer?

 

If you hae a CAI on it at the dealer and there is an engine problem, they could void your warranty if they so desired. If a CAI has been on it and removed, they will not know it. The tuner is a little different. Supposedly, Ford provides dealers with software that will tell them if a tuner has ever been installed. There has been some debate of the software's existance, but I was told by a service manager that it exists. So, if a dealer wanted to check it out or Ford asked them to, they should be able to see "footprints" from a tuner.

 

I am good friends with a service technician at my local ford dealer I will ask him if they have software to check if "footprints" from a tuner can be detected.

 

yes

 

You said the pcm is programed with stock intake wich is true. But when you install the cai your suppose to disconnect battery atleast for my volant I was suppose to. Then the memory is cleared and your engine learns to run with the cai. The first few days after install i had really bad mpg then it went right back up and for city went higher by a mile or two. Throttle responce increased drastically.

 

Yes, the battery disconnect is to clear what the computer has learned from your driving patterns. It still does not make it able to detect a volume of air outside the parameters set in the program. That is not possible.

 

erasing the kam doesn't do a darn thing for the transfer rate and the reading of the amount and velocity of the air pass the maf....