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Problem:
Installed aFe Magnum Force Stage 2 Si according to the instructions, but two days later the CEL light illuminated while I was idling. (Install pictures attached)

Code:
P0171 - Bank 1 Too Lean

Corrective actions taken:
Unmetered air seemed to have been getting into the system somehow. Re-seated silicone coupling, double-checked the MAF sensor to confirm that it is facing the proper direction of flow. Cleared code.

Results so far/Notes:
I noticed that the MAF insertion point fits loosely compared to the OE intake tube. The stock O-ring does not seem to be large enough to accommodate for the increased size of the hole. No other O-ring was included in the box.

Question:
Has anyone else run into a problem like this with an aFe intake box, and if so, how did you correct it?

If this code continues to come back, I cannot use this intake box on my car, which would be a shame because it sounds very good, and I am happy with the sealed design. I have read some threads about this problem, and many said they fixed it by re-seating the silicone connection as it is a little more sensitive to sealing than the OE connection. The code has not yet come back, and I do not subjectively feel any negative changes in how the engine is running.

Solution:

Create a small foam seal around the MAF, or buy a larger O-ring. The O-ring can be found at AutoZone. The part number is 80024.

[Jeff@TopGearSolutions]

Contact AFE and see if they made a revision and or will send you a replacement. They usually do with enough pictures and info supplied. Seems like a manufacturer defect which should be covered under their warranty.

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Originally Posted by Jeff@TopGearSolutions

Contact AFE and see if they made a revision and or will send you a replacement. They usually do with enough pictures and info supplied. Seems like a manufacturer defect which should be covered under their warranty.

It's very possible. I am going to give it another few weeks and see how it does. I just remembered that the silicone flexible coupler came in the box as round, and not oval-shaped. It could be that it just needed to conform to the N55's oval-shaped ducting.

As for the MAF sensor, I'm going to look at finding a larger O-ring just to be on the safe side. It's probably not leaking at all, but O-rings are so cheap that it's best to at least give it a shot.

It's P/N 13627532318, but I don't have any other diameter/cross-sectional information. I might just have to bring it into a store and eyeball it.

If anyone is skilled enough, this is an O-Ring chart I can use to order a new one online. Any help would be greatly appreciated.

http://www.oringwarehouse.com/files/...-sizechart.pdf

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Update. It's been a little under a week since I've re-seated the silicone coupler, and the code has not yet come back. It looks like everything is all good. It must have needed some time to conform to the proper shape.

[Shashkastorm]

Hey guys - I'm a relatively new BMW owner (about 6 months into my 2011 M-Sport 335i). I actually had the exact same issue with the aFE Stage 2 sealed intake - about a week after the install I got an "Engine Too Lean" code. I may take a look at trying to adjust the seating of the silicone coupler - how much did you tighten your pipe clamps - I may have gone overly tight based on your photos.


I ended up buying MAF cleaner from a local auto center, sprayed the sensor down and reinstalled which did clear the code. Unfortunately a few weeks later, I got new SES codes referencing a "Cylinder Misfire at Bank 1" (along with a few others I can't remember right now). At that point, I decided to reinstall the stock drop in filter, and the codes have since disappeared.


I definitely love how the intake sounds, and there does feel to be slightly less lag in spool time, but don't want to drive around with an SES light all the time. Does anyone have any suggestions as to possible causes for the misfire - could it be related to the coupler / MAF seating on the intake, or something else?

My thought was that maybe my spark plugs / injectors need to be replaced soon - I'm only at about 35K miles, but have been running a software tune for the past 5K miles. Other than the tune, the car is completely stock (besides the currently uninstalled aFE intake).

[SUPAN]

I am on same air intake ... Have similar issues ... took them out and refix it ...

issues gone ...

Spark plugs and ignition coils has to be in top condition as well.

I am on NGK plugs for the n55.

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I spoke too soon. The CEL came back, then went away after 3 duty cycles, then came back again. I reinstalled my stock intake, and after 3 duty cycles the CEL went away again. In fact, all I did was idle for about 20 minutes and it turned off by the 3rd time I started the car up. Wherever the leak is coming from is just barely enough to trip the light.

Power delivery is immediately more even and smooth as well. Unfortunately, I can no longer hear my turbo spooling

Seems like it's defective. I'm fairly disappointed, I loved how it sounded. I am going to get an RMA for it and hopefully get either an answer about why this code is coming up, or get a refund. I did notice how loosely the MAF sat in the housing upon removing it, so maybe leaks were coming from there. The MAF sits very snugly in the stock intake. Oh well.

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Just in case someone else out there on the internet runs into this problem:

aFe sent me a new intake. Same problem, same test results. When I reinstalled the BMW intake and did 3 duty cycles, the CEL went away naturally.

I noticed that the MAF fit inside of the aFe intake loosely again. Before sending it back to them and getting a refund, I decided to give one more idea a try. There are only two places it can leak: the coupler, and the MAF. The coupler seals fine, so I took that out of the equation. I did a smoke test and saw the MAF was not sealing properly.

I headed to AutoZone and looked for some O-rings that might work. Lo and behold, one of the O-rings for various distributors fit. Sorry, no picture of it since I've already got the MAF installed, but it's pretty darn easy to find the right one. Just line up the O-rings with the intake and find the one that just fits inside the hole. After replacing the MAF O-ring with one of these, it fit like a glove.

Here's a picture of the pack. The part number is 80024.



It was $4.99 in the misc. parts section. Head over to where they keep power steering caps and whatnot, you'll see these distributor O-rings there.

I'm going to give this another week and see if the CEL comes back. If not, then success! If it does, well, I'm out of ideas.

[GR1P]

Please be sure to send this info to AFE

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Yep, I've been sending all of this info on over to them. They're just as confused as I am! They want me to meet up with someone from aFe in my area to take a look at it, but he's 2 hours away and I don't have my heart that set on this product...

They said they've sold 11 of these in the past month and no one else has contacted them about the issue. Seeing as my car is as stock as it gets and isn't modded (yet ), it's very odd indeed.

Their customer service and support has been phenomenal throughout the whole process.

[PeteA]

I have this intake. My O-ring didn't seal like OEM either (neither did AnooooooH's)

I noticed this during the install, so what I did was surround the opening with a rubber / foam strip. I then installed the MAF sensor and screwed it down which caused it to seal up nicely.

I doubt many do this though, as it was just my OCD kicking in. Not had a single error code in 6 months of use.

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New O-Ring seemed to fix it. I let them know about it. It's just millimeters too large. Good idea on the foam seal

[Shashkastorm]

Following NBA Jam's advice, I purchased the same set from AutoZone and made the replacement - I used the second smallest O-Ring in the set, and it is very simple to choose the right one (especially when comparing them to MAF's stock O-Ring after removing it). The MAF definitely fits more snug with the new ring and I'm happy to say that so far everything is working without SES notifications.

Thanks again for the writeup - It's great to hear that turbo again!

[mike@x-ph.com]

Glad you got it solved