4.6 3v po171 and po174

Hello all, I have an 06 explorer limited with 82,000 miles that started kicking po171 and 174 the last couple of days. I installed a k&n fipk about 3k miles ago.
Ive been poking around here and on the web and every one seems to think its a vacuum leak, however I have sprayed the engine down with carb cleaner and I can not get the idle to increase. The engine almost feels like it is missing not really under load but more when you let off the throttle. I plan on getting some maf cleaner tomorrow to try, even though I pulled it out tonight and it looks spotless. All of the references to this problem point back to the older explorers with the 4.0 or the 2v 4.6, I cant really find any info on the newer stuff. Thanks in advance!!

had the same problem. ranchero saved me major time with this link:

http://www.explorerforum.com/forums/showthread.php?t=314670

try to find this elbow and get a good look at it. it might not even looked cracked on first inspection, so take it off and get a real good look at it.

apparently my explorer is different being a 2006 3 valve, mine does have a hose there but is a solid unit from bend to bend, anyhow I took it off and put the ole sucker on it and it held tight for a good while. I checked all the vac hoses that I could and they all visually look good. Hopefully there are some other suggestions out there. It also appears the gas mileage is suffering significantly I will get some exact numbers on the next tank and I will keep you posted.

Well I cleaned the mass air sensor and still no better any body have any suggestions?

i have the exact same problem. i have an 06 with a 4.6. i put a k&n intake in and after about 300 miles it popped both codes. i tried maf cleaner and even a new maf neither of those worked. i ended up getting a tube of k&n sealing grease and i put it on all the seams. so far its worked. ill let you know if it stays that way. as far as gas milage goes, mine hasn't changed from before i installed the intake. im averaging 16.5 mph.

P0171 System Too Lean (Bank 1)

Basically this means that an oxygen sensor in bank 1 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.

Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.

P0174 System Too Lean (Bank 2)

Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is generally the side of the engine that doesn't have cylinder #1.

Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.

Now go check your O2 sensors. My buddy's 98 Ex 4.0 had these codes. Changed sensors and it fixed the prob.

So cleaning the MAF wont neccesarily cure it. There are sites on the internet where you can look up these codes. You should also have a book that came with your scanner. Or go to Autozone, O'reilly, Advance, NAPA etc. They can read them for you and tell you what they are.

I changed the maf today and so far it seems to be better I probably put 150 miles on her today and no light yet. I got almost 18.5 mpg today but I have the intake and the hypertech programmer.

Well its been a couple weeks and now the cel is back on. Ive ordered a couple of downstream o2's from Rock Auto. Anybody else have any suggestions?

well i changed the o2 sensors and the cel came back on within 50 miles... running out of things to try here anybody else have any suggestions??? I feel like im talking to myself...

i dont think your sensors are off, they are probably doing their job. if you installed a new intake, somewhere there isnt a clamp tightened down enough and too much air is being sucked in giving you a lean code.

after double triple and quadruple checking and hosing the entire intake down with carb cleaner there is no leak on the intake...

any other suggestions????

i put the k&n sealing grease on each connection i also put hose clamps on every connection. that was in mid april and its now june. i've yet to have the codes come back. it was a cheap fix and it worked.

Did you reconnect the breather tube from the passenger valve cover? what did you do with the hose that connects to the stock intake tube from the brake booster line?