I just installed my BHAF from Napa yesterday and was very impressed with the kick in spoolup I received however after the install I noticed that there was a pretty loud knock coming from the engine compartment. you could only notice it when you were idling. The truck still had tons of power and I checked the fuel pressure yesterday and it is holding at around 12 psi at idle and 7-8 at WOT. I pulled the BHAF off today and ran it at idle with no intake, the knock was gone. I installed the stock intake back on, and again, no knock. I am confused as to how the BHAF could cause that, I thought maybe it was banging against the hood but ruled that out after checking. Any suggestions would help because I loved the way the turbo sang with it on. Thanks guys(and gals).

Bryan

 

Mine seems to suck forward a little when running then thump when I let off of the throttle abruptly. I fastened it down with large snap-ties.

 

Could the metal screen around the filter be tapping on one of the screws on the shock tower that hold the air box?

 

I Would Try To Secure It Somehow Ties, Baling Wire, Etc. The Try It Out.

 

Thanks for the suggestions guys. It is pouring outside right now so I will try it out tomorrow. I will keep you guys updated.

Bryan

 

Mine does the same thing. For the most part I can only hear it when I have the hood up.

 

What is a BHAF filter? Air? Does it help? I've been heasitant to change the stock air box. Is the turbo louder?

 

Big Honkin Air Filter. It's an incredibly large air filter from napa and other various stores. It offers about the best flow you can get through the stock intake and more than the average owner will ever need.

Louder turbo, cooler egt's if the stock filter was a restriction, etc... etc...

 

Anyone have a part number? Is there any differenct between this filter and the aftermarket expensive filter systems?

 

Napa 2790

The aftermarket systems use different filters and usually replace the factory accordion pipe that goes from filter to turbo.

 

You should mount your filter minder in the back side of the filter and then you'll know if its sucking down first off...

 

Does it matter if you have the sock over the filter?

 

Not really - the prefilter just makes the BHAF last longer.

 

Ok, thanks. Just ordered the filter. Big price difference depending on where you get it. Napa web site said $73. The Wix through a local parts store is $69. I ordered it through the local Truck Centers from a Donaldson part# and it's $45.

 

Try here: www.fleetfilter.com:

http://www.fleetfilter.com/SearchResults2.asp

BTW, the prefilter also helps keep water off the paper BHAF.