Cold air intake issues (K&N) (P0171 code) "system too lean"

Not really sure what your point is here, oiled filters screwing with sensors is a well known issue. As far as people being dumb, ya people are dumb, some even buy oiled air filters even though they give no benefit, give inferior filtration, and are known to cause issues. The op asked for help and a MAF sensor fouled by oil is a legitimate cause for that issue, not misinformation.

 

Whoa dude, chill. You came in strong suggesting that all K&N oiled filters are garbage. We are simply providing proof that K&N filters when oiled properly are not a problem. Obviously incorrectly / over oiled filters are likely to cause MAF sensor issues.

It's just not a set-in-stone rule that K&N filters will coat the MAF.

 

Group A understands.
Group B thinks group A is crazy because they can’t achieve the same results. People will do what they’ll do.

 

Group A spent money on it and must justify there purchase
Group B sees the data and understands all the possibilities

 

You made a blanket statement, and there is evidence that it's not the whole story. Doubling down on it isn't going to win you an internet award. No need for the group a/b tension.

 

HE STARTED IT

 

I'd be shocked if the "first oiling" from the factory caused issues. From what I've seen the issues arise when the end user supersaturates at the first re-oiling interval. I ran a K&N for long enough to get past that first re-oiling and didn't douse the thing, and never had MAF problems. But my DIY expertise doesn't end after I put a box together with 6 pre-threaded screws either.

 

I would think it's similar in terms of logic to the don't change your transmission fluid if you haven't before. The customer probably gets a new intake / filter cause they have poor performance or maintenance issues, and then after that the light comes on. It's gotta be the intake, cause that's all the touched.. when it could more likely a be handful of other things which just happened to surface at that point.

 

Or it could be a fouled MAF sensor, due to oil being introduced to the system by an oiled air filter .

 

Love beating the dead horse don't ya?

The OP said it happened after a day. The filter would have to be SERIOUSLY over oiled for the maf to get coated that quickly. So like I said originally:

 

Follow this other thread too. Same issue but with a supercharger involved and other procedures completed.

https://www.tacomaworld.com/threads/p0300-p0303-p0171-diagnosing.762787/

 

Do K&N Filters protect against 5g

 

Only if you oil them twice a month. Otherwise they amplify it

 

Is your new air filter closer to the MAF sensor than it was before when the air box was there?.....I have a 2004 Escape that gave me a p0171 code after CAI install, and the only issue was my new filter was too close to the MAF sensor and it couldn't read all the air coming in properly as it's a lot more air a lot faster than with the box......it doesn't have to be exactly where the old filter was, but close to the same distance or further away.....preferably pointing directly at an air source coming in to your engine bay....I ran mine down to where the holes are in my bumper for the fog lights and pointed the filter right there and the code cleared itself......99% of the time it's something stupid.....just remember p0171 means unmetered air....so your problem will most likely always be right at the sensor or after it....but never before it....if you were having any kind of fuel deliver issues prior to installation, you may want to check that too as a weak pump or clogged fuel filter can throw the same code.....

 

Now that it's two years later, pretty sure he solved the problem.
Given that it threw the code after he put the K&N "CAI" in, it's pretty clear what the cause of the code was.