Gregs04.5

I just recently picked up the 2000 996 shown on the left, there are a few issues (IMSB is not one of them, thankfully)
While searching codes P0154, and P1119, I saw a common thing, that is the K+N cai. The PO did keep, and give me the original air box, I think I'll swap it back in.
I'm thinking the K+N flows more air, but at a lower velocity, thus messing with the expected values from the MAF.

Any thoughts?

Thanks, Greg

wyovino

There are many, many threads about that here. Most would suggest that you re-install the original air box . Your car, your choice. But I would read the threads. And congratulations!

hatchetf15

^^^+1

dporto

Original or 997.1 air-box only anything else is a compromise.

Flyfishnick

All I can say is that I was in exact same boat. PO just installed before selling to me, I got codes, cleared them and they kept coming back every few weeks, so I went back to stock and have never had a code in 2 years. Sold the K&N kit to 808Bill and he has had no issues. Can't explain it why it works for him and not me--definitely odd for sure.

az968gpw

You can certainly swap them and see the differences, easy job. You'll likely gain a few hp and lose a few codes.

Gregs04.5

I have the stock air box, and am convinced that re-installing it is a good idea. I need this to run without codes so I can pass emissions here.

Thanks, Greg

Weazer

When I purchased my 996, it came with a new K&N cold air kit uninstalled. So I installed it and got one code, cleared the code and it never came back. I like the look and sound of it compared to the original, and it has a sheet metal box/shroud that isolates the conical air filter from the rest of the engine compartment and vents directly to the original cold air snorkel. I dig it and its not causing me any problems, so I'm keeping it!

pdxmotorhead

One key to a MAF functioning correctly is laminar flow across it,, I would not be a bit surprised if
the root of the problem is the positioning of the sensor and the overall install of the Filter.
Hot wire MAF sensors don't like buffeting air, its why many applications have a honeycomb air director
before them in the intake. The more tube in front of the MAF the better (to a point) And
avoiding anything that would cause the air to tumble ..

If the oiling is uneven on a K&N it can do
some weird stuff. I switched out a Hilllborn K&N setup to a Foam Media system and it got rid of
some surging problems when the car hit cross winds.. The car pulled better a thte top end with the
K&N so the owner like to run it..

Eventually changed the hood on the Sprint to go lower on the
leading side and that fixed the issue, and this wasn't even a electronic system.

I eventually figured out how to really get a good consistent coat
using a cheap harbor freight paint gun to apply the oil.
And run a over filter sock so I could pull it off between heats and
put a clean one on to easily get rid of the mud that would build up.
(Remember this K&N was 30" long, 14 wide and 14 high.. It covered the whole system. )

az968gpw

My 996 came with an Evolution Motorsports air box. Never any codes. Air box includes a snorkle so it pulls in outside air just like a stock box. Dry air filter cone so it doesn't get oil on the MAF. I like the looks and sounds and it probably adds a few hp.

Had a k&n on my 968 with the modified air box and it was great, esp since the air box forced in outside air thru velocity stacks.

Have an AES cold air intake on my Tacoma with a Green filter and love it. It also has a forced air intake.

But I've read not good things about the k&n with the 996. I think it the lack of forced air so it pulls hot air from the engine compartment, thus robbing hp and seems to throw error codes.

YMMV.

808Bill

Over oiling is the biggest issue fouling MAF's..

lowpue

Dundon tested air temp and HP with and without cold airbox. We got better performance with stock. We found that more engine heat was sucked in with cold air kits....in my case we measured 20F higher air temp for "cold" air kit....

808Bill

I believe it.
My new motor will go back to stock (not quite) 3.8 upgraded airbox if I can find one.

lowpue

Definitely the way to go. Totally agree

Flat6 Innovations

If you want a choppy idle, MAF readings that are improper at idle, and hotter air inlet temperatures, go ahead and buy an aftermarket system.

Last week we made 480HP with a bone stock 3.8L OEM airbox. #FACT