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      11-06-2013, 04:49 PM   #1
Vanon
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K&N air filter: popping noise from the exhaust?!

Hey guys,

I bought a K&N panel filter today for my car and it seems to run better, a bit smoother, at least above 2000 rpm.

The problem is that when I got back home I noticed a "popping noise" coming from the exhaust every time I took the foot off the gas... a "backfire"!

Isn't it a BAD thing? I mean, a backfire happens when the engine is running lean (AFAIK), but the ECU should re-calibrate the air-fuel ratio, avoiding this kind of crap... so should I be worried? Or maybe the ECU needs some time to get used to the new filter?
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      11-06-2013, 07:44 PM   #2
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yea this is true, i have it also! but only really happens when you floor it and lift up...
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      11-06-2013, 07:52 PM   #3
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This is just a quick response until someone comes up with a more accurate answer.

Some guys here installed the K&N filter. Let's just skip whether it actually improves power....

We do find when the filter goes on, the turbo wastegate is louder, some report a whirling noise coming from the engine bay, possibly attributed to the filter.

I am no expert why the backfire pop happens, but, my car also has this popping sound when I slide down ramps in parking garages. It happens the most in second gear when I am travelling less than 30 km/h. I don't think the popping sound should necessarily be equated to backfiring. You can always have your dealer check for the engine timing or other things, but I guess you're ok especially if you've not noticed any drop off in fuel economy

Hopefully it eases your mind somewhat until more expert answers come along
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      11-07-2013, 12:30 AM   #4
ovekvam
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How can a panel filter from a different brand change the sound? I know open cone filters will do that, but panel filters?
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      11-07-2013, 04:42 AM   #5
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you just made me consider a K&N air filter
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      11-07-2013, 10:22 AM   #6
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The K&N filter was my first mod and yes the 'popping' noise you describe was louder with it.

I've since had the M Performance exhaust added and the noise became louder still, almost akin to a touring car's bark on overrun.

I like it and fuel economy wasn't compromised at all.

I would add that the noise is far more noticeable in Sport and Sport+ mode and more muted in Comfort and Eco.
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      11-07-2013, 12:14 PM   #7
Vanon
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Thank you all for the replies guys!

So there's nothing to worry about? I was a bit scared last night... and BTW fuel economy seems to be almost the same.

Quote:
Originally Posted by rs-6 View Post
you just made me consider a K&N air filter
Ahaha yeah go for it! I always changed the air filter in my previous cars, doesn't improve the performances at all but the engine runs smoother (at least in my experience) at high revs and if you plan to keep the car for some years it's even cheaper than changing the filter every 20k km since you can clean it!
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