Stock Airbox vs. Cold Air Intake

[roadbiker_2]

All, I have a 05 ZHP that was purchased with a K&N Cold Air intake setup and have had issues with throwing P0171 and P0174 codes at highway speeds with both cruise on and general driving. Speed has been around 75-80 MPH.

Anyway, the first time it did this I had the car taken to a BMW independent shop as the car was 4.5 hours away and had them look at it. He smoke tested it and said it had some vacuum leaks and the CCV needed to be replaced.

I did the CCV replacement and put the Cold Weather CCV on the car as it didn't have it on there and I live in Illinois and replaced all of the boots and other rubber items including the o-rings on the fuel spreader. Cleaned things like the ICV and throttle body and rebuilt the DISA with the Titanium rod kit available on the internet.

The car runs beautifully, but I still get a nuisance set of codes every now and then on the highway. Sometimes it will go a week, other times it will throw the code in say 50 miles or so.

Anyhow, today I went to a Certified Mechanic and we used his Snap-on scanner to look at the Fuel and O2 sensors and everything appears to be in line, we even did a scan before cleaning the MAF in case it was causing the issue with being dirty. Signals look very similar both before and after cleaning the MAF. It was suggested that I go back to the stock Airbox as it is more stable and can prevent a harmonic issue as he was calling it, at speed. In other words, the cone shaped air filter was causing some resonation issues and was causing false readings at the MAF.

Has anyone else experienced issues with their Cold Air Intake, and would they care to share their experience? Also, is anyone selling a standard stock Airbox on a car that is being parted out?


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[cornercarver]

Haven't had this issue on mine, but as I understand it the MAF doesn't like turbulent air. Ideally it should be getting sucked straight through, so look at your CAI and see if the way the air enters the box is causing it to blow at the filter from an angle.

[Reasoned1]

I installed a K&N CAI on my 2004 330xi last year, and I like it--no issues other than the common jingling at light throttle. I'm about to install the same on my 2004 330i ZHP. I'll let you know how it goes... although I won't be running it until springtime.

[roadbiker_2]

All, not sure what the jingling you describe would be, this car runs so smooth at idle that you almost can't tell it is running. Anyway, perhaps the air is getting disturbed, does someone know what the stock filter looks like for the K&N? I will post what is on mine and let me know if this is right. Perhaps the prior owner put on a different filter.


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[roadbiker_2]

This is what is on the car.


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[hcbeck2689]

I have a stock box you can have if you want it.


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[Rovert]

Do you have that screen on that evens airflow out? You put it in between the filter and MAF. Or is that only S54? I had a stalling issue then i realized I need to use the screen inside my OEM air box. Once installed I've never had an issue since.

[roadbiker_2]

http://www.knfilters.com/mobile/mPro...x?prod=RC-4630


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[roadbiker_2]

This is the filter that should be on that intake. Interesting that it has the cover at the front


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[3ZHPGUY]

I've had a Dinan CAI for years and didn't have any issues with it until a few years ago. Had it checked by the Steelership and thy said I need to start with replacing the MAFS. The car doesn't give me any performance issues except an occasional rough idle. With the MAFS being +$300.00, I jut live with it.

I've heard the oil on the CAI may have something to do with it.


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