I am installing on someones and in the instructions it says MUST HAVE A TUNE. Im not understanding why? Anyone install without a tune? Since when does it matter if you have a tune or not for a k&N filter
I had never installed one, but i figured it out once i opened the kit. Its the same as any vehicle, you get a bigger MAF you need bigger injectors. Or a tune. This kit comes with a aftermarket MAF housing, that allows for more air. Good idea, but you now need a tune because without more fuel youre correct youre going to run lean. Pretty simple idea i guess. Good way to make money off of a tuner.
You need a tune because the MAF housing is larger then the factory unit. in turn throws off the MAF sensor. I beleive the have to modify the MAF transfer functions in order to compensate for the larger MAF housing.
Also the reason you run lean is because the maf is taking say a 2.5V reading at Part throttle. With the larger MAF housing. But with the stock maf housing the same Throttle position might make the maf output a 3.0V reading. so essentially the MAF reports its getting less air passing through then it actually is because its calibrated for the smaller housing that doesnt allow as much air to pass by the sensor relative to that throttle position. so then its getting to much air but the injectors are of course putting out fuel for the amount of air the maf thinks its drawing in. then at the end of the chain is your O2 sensors which start to throw a lean code because there is way to much air in the emmisions according to what the pcm thinks there should be relative to the MAF's reading. and this is true. why because the larger maf housing.