No it all makes sense. I heard of the Gillette hack before. Same same but different.

 

I did the 'orange cap' mod so I could observe results for myself. The following describes my experience.

The Install
Remove 3 hose clamps holding the intact duct to the throttle body (1) and to the air box (2). Gently remove the duct.
I used an Edge shaving cream cap. Firmly press it into the duct where the duct goes into the left air box opening. It will be snug but will go in as far as the ducts shoulder - 1/2 to 3/4".
Trim the excess cap even with the duct. I used a hack saw and cleaned up with a razor knife. Don't nick the duct.
While you're in there, douche out the throttle body. I used throttle body spray cleaner and a couple of paper towels. Repeat as necessary.
The modified hose duct will fit right over the corresponding air box outlet.
Carefully reassemble watching for potential air links.

Observe Results
Sound - Yep, sounds way cool. At more than mid-throttle and above 4K rpm, she sounds like she means business. Way cool.
Throttle Response - Here was my first indication that all may not be well. The throttle feels notchy - over sensitive both on throttle and off throttle. SOrt of like when you were first learning to drive. Hmmm.
Mileage - Fuel mileage immediately dropped 10-15% in street driving. More Hmmm.
Power - lacking a chassis dyno, I can only say that it feels a little stronger.

The Why
Apparently Porsche engineered the little bypass to reduce intake noise. Good for daily drivers, not so good for enthusiasts.
In so doing, they apparently adjusted the tune since only a portion majority) of air flows through the Mass Air Flow (MAF) sensor.
Our 'orange cap' bypass now sends 100% of the air through the MAF. IMO, this results in an overly rich mixture.

My Conclusions
I took the 'orange cap' out after a week and returned to the stock configuration. Sound is cool but not at the expense of efficiency.
I might try it again at a track day to see if it helps my lap times. Hard to believe a richer mixture would generate more power. Lean makes power (within stoichiometric limits, of course).

Questions
When you put in yout cold air system, did you have to put a new tune in your ECU? It seems to me you'd have exactly the same issue.
What is the recommended cleaner for the MAF sensor? I figure hosing it down with the right product might be a good thing.

 

^^^ LOL. Do you even know how the system works? Did your even allow enough time for ECU adaptation? Only on Rennlist are the enthusiast so clueless or ocd that a simple orange cap mod thread goes through multiple pages of mud. I truly am ashamed.

 

Welcome home!

 

I drove it for a week and the ECU didn't adapt.
But thanks for your ahole comment in lieu of useful content.

 

Everybody starts out nice until the same stuff gets onto page 11 for something so simple. Imagine if you had to explain how to turn on the computer to your mother several times. Your tone will start out ok and if she still doesn't get it 5 hours later, you will most likely find yourself shouting.

Something is wrong with your car other than the orange cap mod if you're car is acting weird from that. No one else afaik has had any issues.

Either way you were able to resolve your issue. It's just that you won't have the cool sound like the kids with cards in their spokes any longer.

 

Thanks for the thoughtful reply, Alpine.
FWIW, I'm not a newbie - the 996 is my 5th Porsche over 25 years. ANd I do all of my own work. But the 996 is ... different.
There doesn't seem to be anything "wrong" with my car as it runs like stink, gets respectable mileage (20/26), and I track her on occasion.
May I ask how long it takes the ECU to adapt to significant changes? I figured a week should allow it to adapt, but it clearly hadn't. I assumed it was because of some hard limits Porsche built in and possibly that the MAF sensor doesn't see ALL airflow, only a portion.

 

Are you sure you checked all connections to make sure there wasn't any leaks? One thing you can do if you feel like diagnosing it is to get either a Durametric or an app like torque for Android with a Bluetooth dongle to read and log the MAF readings with and without the mod. They should be very similiar.

OR just replace the factory intake hose with a silicone $30 ebay one. That way you don't have to worry about sealing off the smaller Y hose reducing any install errors. This is what most are doing.

 

Thanks again, Alpine.
I'm pretty careful but a leak is always possible.
The cheapest silicone hose I can find is $79.
Do you have a source for the cheap eBay unit?

 

Hmm, all the air is going thru the maf, even with out the cap mod.
The hose that goes to the airbox, connects to helmhoz resonator and does nothing else than reduces intake noise.

If your car is running lean, there is leak in some other place.

Sorry if you all ready said it, but how did you check your afr's?

 

so the end resume? is it worth spending 300-400$ for a kn cold air kit, or this mod does the same trick? (more noisewise, don't believe in power gains just by swapping an air filter)

 

IMO no, it's not worh it. Stock airbox is good. You can use kn filter inside the stock airbox.

Remove the helmhoz resonator completely from airbox, this will make it flow litlebit more. No I don't have test results for this, based on my experience only.

 

http://www.ebay.com/itm/Porsche-996-...178bf3&vxp=mtr

It also comes in Red, Yellow, Orange, Blue if you want additional HP.

Sound is the main reason. There's been a little improvement shown if you get the silicone hose, remove the resonator box for more air box volume, and get a drop in filter element. That's the best and most economical bang for the buck setup IMO.

I have tried 4 different intake setups. Currently running Evoms but really the combo I listed above is the best bang for the buck and has been dyno'd be a member here to pull in very similiar amt of hp with an otherwise stock setup compared to aftermarket systems. Of course intake companies will have you believe otherwise.