P0171 Lean
 

So i am getting the P0171 code. lean on bank 1. I have a 99 with 150k.

The MAF was replaced at about 85k and cleaned about 1 month ago. Could this be the issue again?

I have read several post about this code and I dont see any effective way of narrowing it down. I'd hate to buy $100 sensors not knowing if its going to fix it.

Could be. Do you have a K&N oily air filter?

no. regular paper filter

check the following...
 

If you have any vacuum leak, will give you a P071, take a look at all of your vacuum hoses and replace them if they cracked or loose. And inspect the pcv grommet or just replace it, their cheap. You can tell if you have a vacuum leak when you press on your brake pedal and feels soft, instead of being firm. Next change the fuel filter and air filter if you haven't done so already. If these don't fix the P0171, then replace the maf with a toyota/denso part.

You can go around the engine with a propane bottle opened slightly and if the idle speed changes, you have a vacuum leak and it will also be real close to where the propane is. A dirty or defective MAF would give you some noticeable power loss. Any symptoms besides the code? I seriously doubt the MAF you replaced 85K miles ago is already bad unless you're getting water in it or something.

Does an kN air filter cause this code..i clened my filter yesterday and now i have that issue..

Can this issue be caused by a KN air filter.. i cleaned mine testetday and now i have this code...

yes, when you oil them and you use too much (it's hard to use the right amount) the oil gets sucked through the fitter and coats your MAF which then gives this code mentioned above, so now you get to find the MAF write up and practice that one, next time when you oil it shake it out a bunch of times to get the excess off, or try not to be such a bro next time and just rock the paper filter like everyone else, lol, j/k and just giving you a hard time, the k&n's are ok but they do have this issue, just watch it next time.


to the op, i see like the others do, vacuum leak>MAF, much more likely to be a vacuum leak in your case, how does your 4wd engage? if it lags it could be from these lines, but really could be coming from anywhere , the propane one is a good one but i prefer to just go over with a flash light and take my time before i start doing things like that, though that does work it does freak me out a bit, i'm just not as manly brian in some cases, lol ;-)

Can you help me find it.. im on my phone and it takes for ever...the truck came wirh this filter.. is there a diffewnt cone option i can get.. and can i clean my maf??

yes you can clean your maf, it's a bit scary at first but very easy, just be careful not to knock any dirt further down, go slow and be very clean.

write up
4Runners.org - Cleaning Your Throttle Body and MAF

my learning experience with this
http://www.toyota-4runner.org/3rd-ge...-we-speak.html

book mark this page on your phone...seriously...do it.....do it now....it has all of the write ups in one place and can answer a ton of questions quickly without having to post here.
http://www.toyota-4runner.org/3rd-ge...reference.html

soooo you got a cool air intake thingie huh.....as far as alt. filters for those i don't know go to the performance section of this thread and ask that or see if someone chimes in here, best bet in that case is to just be careful when oiling or pull it out, but i aslo don't know about that either as i don't run the cold air intake....and honestly unless your super charged or have a way to make better use of the cold air i think those things kind of useless on our motors....imo, sorry i can't help you more on the "cone" filter question, it's just not my area of expertise , ask someone who's (still) running one of those
and see what they say, i just know more then a few fellow users ditched them after a while....