Hissing Noise

[HARLEYTRUCK]

Hi, I have a 2002 supercharged harley davidson f150 and i recently put a K&N Intake on it and now when the truck starts when its cold it makes a hissing noise until it warms up. Does anyone know what that is or have experienced it themselves? Thanks

 

[blue88mustang]

K&N kits and/or stock replacement filters typically allow more engine noise to be heard from inside and outside the vehicle.

I would double check your hose clamps, but odds are it is completely normal to hear more of a sucking/hissing noise coming from the intake.

 

[HottRodd351]

what about the obnoxious intake moan? I changed the iac and it moans all the time and i do mean MOAN LOUD!!!!

 

[oki]

Very normal to hear the K&N moan...it is so easy to spot/hear that a ton of ricers do only that or anyone in any car just change to the K&N and say they have work done to their cars. Get used to it, as it won't change

As for the hissing...its the filter allowing more air flow and just generating more audible sound. If you don't have a CEL then you don't have a vacuum leak anywhere...of course you can check to see if you do as the CEL won't always turn on but 99.9% of the time it does.

Once I started increasing the power in my truck, even before it was built, I had the K&N CAI GEN II on there and when I let up off the gas after a WOT blast, it literally would sound like a blow off valve shooting air out.

Get used to it, as it won't be changing.