Just recently purchased an '01 F-150 SuperCrew 4x4 with the 5.4L and I love it. The previous owner did some performance enhancements like a Volant cold air induction kit and installed dual tail pipes from the low restriction muffler. Shortly after I got the truck, the service engine soon light came on. A code reader says P0171 "System too lean" (Bank 1), and P0174 "System too lean" (Bank 2). I've noticed a few replacement fuel injectors and I don't think any are dirty or clogged. Could the OBD2 need to be reflashed because of the cold air kit? Maybe a dirty fuel filter is restricing fuel to the injectors? The truck idles and accelerates fine but when cleared, the trouble light comes back on. Bought truck from dealer "As is - no warranty" so I'd rather not have to pay dealer if I can help it.
Any help you'all can offer will be appreciated.
Thanks.

 

try and clean the maf , the dumb pre oiled filters get oil on the signal wire and stop the air signal to the computer thus causing the lean condition...............if not get it on a scanner and see what the upstream o2 sensors are reading..............

 

Cleaned and let dry the MAF sensor a while back with battery disconnected. Buttoned everything up, reconnected battery and took 'er for a drive... trouble light came back on. Sorry, I forgot to mention in first post. All I have is a hand-held trouble code reader. Would I need to pay the $80 - $100 for a reading from the real deal diognostic machine at a repair shop for checking the 02 sensors as you suggested?
Thanks.

 

you may have to bring it to a repair shop then and have them look at the live data to what the o2 sensors are doing .........

 

Okay, Thanks for the advice.

 

also you may want to look into a tuner to correct the air to fuel ratio when your truck is running lean it means it is getting to much air prob due to the cai kit that you have on your truck and correct me if im wrong but i think around that year up to around 05 theese trucks ran lean from the factory so adding the cai only worsens that problem if you cant afford a tuner try to get the stock intake setup for cheap and see if the problem goes away

 

Thanks for the suggestion. Do you think the MAF and intake ducting from an '03 F-150 4.6L (heritage) would work? The company truck I drive could become a temporary donor.
Thanks again.

 

to be hones with you off the top of my head i dont know i can get you an answer tho my brother happens to be a ford master mechanic so im sure i can answer any of your questions i will do my best to find out what he thinks but it wouldnt be that hard to look under the hood and compare the two setups also ill get back to you soon bro

 

I sure do thank you for your help.

 

my 01 v6 has the same code readings. been told it could be the maf, the intake being replaced or even the dual exhaust straight out with no muffler...

but now mine has 105k on it, and running rough as ever... autozone ran it and said it was running lean and it need a new maf sensor. replaced plugs and wires hoping it was just miss firing but that didnt solve it. also have been told it could be coil packs... and then yesterday my wiperblaids and fluid quit working and now that its stop raining my windows wont roll down nor dome light turn on. checked all fuzes and only one was number 15 fuse which happens to be speed control which i havent done the recall on the cruse control...

urgh... bout ready to just sell it and be done with it!!