ughhhhh, so i have been struggling with this p0171 code (system too lean bank 1)for over a month now...i have done sum research on BC doing sum research and have done literally everything u guys have said and more and i still cant find the problem.....today i brought the car back into the shop to take ANOTHER look...just so u know i actually changed the MAF sensor and it took the car over a week and half to trigger the code again...but anyway a very knowledgeable mechanic that was there took a look around and basically came to the conclusion that the oil that is used on the aftermarket air filter (in the thrasher cold air intake box) is coating the wire in the MAF sensor and throwing off its readings and as a result giving me the code.....COULD THIS BE?!!! lol long story short we cleaned the wire on the sensor and cleared the code and im gonna go for it again and see what happens....ill let u guys know what happens but i just wanted to see if this is seriously a legitimate reason for the code to be coming up....if so what kind of filter should i throw in there thats not so drenched in oil.. :? its not a K&N that comes with the kit its like a SB powerstack filter or something....thanks guys!!!!

Have you tried pulling the boots off of your battery cables and cleaning the cables with a wire brush/wheel?

i did read that here on the site but havent gotten a chance to do so...im kinda going one by one knocking possible suspects off the list...like today i noticed the boot on one of the plugs is touching the 02 sensor which can cause it..so i wrapped it that way they dont touch any longer...and like i said we cleaned the MAF so well see if it comes back on then i can eliminate those as the possible causes and def go to cleaning the battery grounds etc next...i just wanted to know whether or not this whole oil thing on the filter getting on the MAF could be true, ive never heard anything like it before..

The MAF could be causing it.. however...how much oil is on the filter?

Meanwhile.. not checking your battery cables is probably the worst thing you could do, then check your evap connections..

Im plauged with PO171 as well, generally will come on during warm up.
I have to take a look at my battery connections though still

You sir reversed your evap connections. (Yes..I'm that good)

i did check the evap connections and those were good...now what exactly should i be doing with the battery? im removing the connections to the terminals on the front of the battery and just cleaning them off making sure there is a solid connection? to both the positive and negative terminals?

No, you have to completely remove the rubber boots and check the connections inside as well. Just checking the connection points doesn't do it all. Make sure to put a bit of dielectric grease in them when putting the boots back on. its extremely important that the boots be completely removed.

You can remove the bolt from the boot/cable end. Then the boot slides right off. Look for corrosion.

Once the electrical and evap are disqualified, I would check the vacuum lines. You have some unaccounted air. If it is a vacuum issue... that'* a bugger because there is a good chance it is intermitent. You have to have had enough "good" cycles to clear the code without it popping right back.

If you haven't resolved it. Clear the code, keep a can of carb cleaner at the ready. When the code hits, spray all any vacuum connections, including the TB contact with the intake, PCV, EGR. If the engine stumbles you have the culprit.

note.... if the freeze frame for the code consistently has your idle at about 1100 or less, I would take a serious look at the IAC on the TB because you're failing under non-throttle conditions. They are the 8th Wonder of the World. It'* a wonder how such a clunky, seemingly non-precision part, can perform such subtle adjustments to the idle.