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Hi in the past 1000 miles I have had the P0171 check engine light code come on roughly 4/5 times and I erase the code but comes back. It looks like it comes on when sitting at idle for a bit never came on while driving..only in idle. looked up what is may be(maf sensor,02 sensors,vacuum leaks) I cleaned the maf with crc cleaner and check the hoses amd they all “appear” to be ok. Ats 2.0t all stock except kn drop in filter. 51,000 miles. Any idea what it can be that I’m missing that I don’t know about. Thanks.
 

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Your K&N install makes me think that might be the problem - did you clean it recently?

K&N filters are terrible... they let through all kinds of dirt (you see it in a UOA (used oil analysis)) and they generally don't add power either. I've had friends install them on their cars, and end up with all kinds of MAF issues. More often, I see this when they clean it and end up over-oiling it... which is even worse.

The fix? Get a MAF cleaner spray and try cleaning the MAF, and then switch to a paper air filter and see if that fixes it. It often does, in my experience.
 

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Your K&N install makes me think that might be the problem - did you clean it recently?

K&N filters are terrible... they let through all kinds of dirt (you see it in a UOA (used oil analysis)) and they generally don't add power either. I've had friends install them on their cars, and end up with all kinds of MAF issues. More often, I see this when they clean it and end up over-oiling it... which is even worse.

The fix? Get a MAF cleaner spray and try cleaning the MAF, and then switch to a paper air filter and see if that fixes it. It often does, in my experience.
Thanks for the reply. I just installed the kn filter yesterday(brand new) but still got the codes before install and one again after about 30miles after install. I also did clean the maf sensor with crc maf cleaner during the install. I supposed I can get a paper filter and see what happens. Kind of weird though only at idle when I see it..
 

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Its a lean bank 1 error. Look for a vacuum leak. Check the intake track connections. But could be the fluid you used burning off. MAF could be bad too. Nice thing is they are only $46!

Been using K&N since 1986 on every vehicle I have owned. Have never had a problem. Saves a lot of money over the lifetime of your vehicle and makes a smoother running engine.
 

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I've used K&N before as well, and you certainly can run without a problem if you follow directions. Besides which, many older cars didn't always have MAFs so they couldn't get adversely affected (the car I ran it on had a VAF, for example).

However, if you do even a SINGLE UOA you will see all sorts of silicon from dirt in the oil, because it's not very good at filtering. I have proof myself on my car, and there are many similar results from many other people.

There are better oil-type filters out there than the K&N that don't let through dirt (last I checked, ages ago, Apexi had foam/oil filters that did great) but in the end none of these really improve performance much, if at all, as proven by many independent tests.

If it makes you feel better, then knock yourself out. I'll stick to the facts and keep a cleaner oil... and prevent from ever seeing any MAF issues.


Back to the issue at hand, as others suggested, check the vacuum fittings and such too. And you may try a replacement MAF... maybe get one from a store where you could return it if it doesn't fix the problem. I had a friend with his K&N and he could not clean the MAF to solve the problem (he admitted to over-oiling it)... only replacing it fixed it in his case.
 

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I've used K&N before as well, and you certainly can run without a problem if you follow directions. Besides which, many older cars didn't always have MAFs so they couldn't get adversely affected (the car I ran it on had a VAF, for example).

However, if you do even a SINGLE UOA you will see all sorts of silicon from dirt in the oil, because it's not very good at filtering. I have proof myself on my car, and there are many similar results from many other people.

There are better oil-type filters out there than the K&N that don't let through dirt (last I checked, ages ago, Apexi had foam/oil filters that did great) but in the end none of these really improve performance much, if at all, as proven by many independent tests.

If it makes you feel better, then knock yourself out. I'll stick to the facts and keep a cleaner oil... and prevent from ever seeing any MAF issues.


Back to the issue at hand, as others suggested, check the vacuum fittings and such too. And you may try a replacement MAF... maybe get one from a store where you could return it if it doesn't fix the problem. I had a friend with his K&N and he could not clean the MAF to solve the problem (he admitted to over-oiling it)... only replacing it fixed it in his case.
In regard to your anti-K&N stance. I have proof on my cars too. Dozens of them. All running MAFs. 100,000+ miles on the odometer. All running like new. The fails you speak of exist with paper filters too. The issue is always with the owners lack of maintenance. Its gossip. Your K&N fears are wives tales. Rumor. With all due respect I strongly disagree with your entire argument. But then again, that's why we have this wonderful forum.
 

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In regard to your anti-K&N stance. I have proof on my cars too. Dozens of them. All running MAFs. 100,000+ miles on the odometer. All running like new. The fails you speak of exist with paper filters too. The issue is always with the owners lack of maintenance. Its gossip. Your K&N fears are wives tales. Rumor. With all due respect I strongly disagree with your entire argument. But then again, that's why we have this wonderful forum.
Gauze style filters do work... But, IMHO they offer very little in the way of performance. They are expensive compared to paper filters. They are a PITA to clean ($ for cleaning solution), dry and re-oil (More $ for oil).

Lastly... many folks over oil the filter and end up contaminating the MAF (more $ for cleaning solution).

OBTW - The K&N 32oz cleaner is about $12 and Black Magic Bleach White is $5. Both are using the same main chemical (Sodium metasilicate)
 

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The bottom line is the factory usually has it dialed in for all around function. Can the air intake be tweaked to give a lille better performance, yes. But, at what cost.

Dodge has it all over GM in the cold air department.

Hellcat Challenger uses the headlight to get cool air in.


2019 Scat Pack Has a grill opening that can be use for cool air in with a few parts from the Hellcat.
All of this can be retro fit back to about 2015.
 

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Like I sad, I didn't say it's not possible to run without MAF issues. Please read my reply more carefully. I also agree that it's due to poor cleaning procedures that most of these issues arise.

As for wives tales, the UOAs I mention are facts. Will these automatically destroy your engine? No, of course not... but it will lessen the total longevity. That said, with engines being so well designed these days, it's probably not that big of a deal... after all, losing even a month or year on a 150k mile car would typically only drop the life to what 9 years (assuming 15k a year for a 150k car, you can certainly do much more than that in most cases)? Most people wouldn't complain about that, so they wouldn't notice.

Again, my choice is to save the life as the power increase is not noticeable. As you said, you can disagree and make your choice... but that doesn't mean anything I said is a "wives tale".
 

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So that's what that is! I have a Hellcat that parks next to me at work. I could not for the life of me figure out how she/he got a light punched out when the car looked pristine.
 

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So looks like it was the Maf. New from Amazon was 38.00 pretty cheap. Also was a different part number than the my old one. After looking around online I believe it’s maybe a newer version but the new part number is correct. This was after spraying the old maf with crc maf cleaner which did not work.
 

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You might check your trims in a week if you have the ability to do so. Seems like no 2 MAFs every read exactly the same, although generally are close enough to not warrant touching anything in the tune.
 

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I'll leave this here:
http://www.billswebspace.com/AirFilterTest.htm

As for the video above, no one here has said it doesn't increase some airflow... but even that video doesn't test actual filtration, so it's a bit of a moot point. Beyond that, it's a terrible test since he throws out 2/3rds of the data (taking only the best of 3 runs)... that's a scientific no-no and basically invalidates the results anyway. What's funnier is how his clean-air filter accel test showed a DECREASE in performance versus the dirty filter test. That, alone, tells us that his test repeatability is terrible... he needs to have more data points and USE them, not just throw them out because they don't agree with the desired results.

Again, I'm not saying the K&N won't help airflow, and I agree it will probably increase power slightly. BUT at the expense of filtration, as the ISO test I linked shows. I'll trust an ISO (ie, REAL science) test over this nonsense any day.

Lastly, I repeat, I have personal experience with UOAs showing higher silicon after installing a brand new K&N, and then lower silicon when I removed it. There are many other similar results on the BITOG forums where people obsess about UOAs. The experts there (more expert than me) agree with my findings as well...
 
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