Richie_Rich

I drive a 2003 Ford F150 Supercrew, with a 4.6l V8 Engine. I have recently, within the last few months, had my Service Engine Soon light to come on. After putting it on a computer I have had the codes PO171 and PO174. They mean system is too lean in bank 1 and bank 2. I am no mechanic, how can I go about repairing this without taking my truck to a shop? To catch people up, I have replaced the O2 sensor upstream from the catalytic convertor on the passenger side, and downstream of the catalytic convertor on the back passenger side. Please help, I love my truck and cannot afford to get rid of it.

otto457

Cleaning the MAF and checking for vacuum leaks should be your first step. There are how to's for the MAF on this site.

cjcnomor4

check your pcv hoses, especially at the back of the throttle body.

Richie_Rich

I will check these things and hopefully it will solve my issues. Would these issues cause the vehicle to idle bad and die? It died twice yesterday and it has never did that before.

cjcnomor4

if the pcv hose at the back of the throttle body is rotted through it will idle bad and stall.

Toddman38

iTrader: (5)

Try cleaning your throttle body w/ carb cleaner, probably full of carbon. This fixed this issue I had with my 2007 H3 dying on me while idling at a stop!

BUCKSHOT

If it's as dirty as mine was before being cleaned, you will notice a considerable difference in the performance of your truck after the cleaning. I am not talking a slight difference, I am talking a night and day type difference.

Richie_Rich

Thank you for the advice. I will be sure to check all of these and let you know the outcome.

Plague

It depends on how rotted the elbow connecting the PCV line to the the TB is. It would idle bad but it wouldn't necessarily stall if it's just barley leaking.

Either way checking for a vacuum leak and cleaning the MAF sensor should be the top priority to try and track down this problem.

Richie_Rich

Well I cleaned the MAF sensor and cleaned the carburetors and the throttle body as well. I unplugged the battery for 30 minutes. I have driven 71 miles so far with no Service Engine Soon light on, though I know I have to drive farther than that. Now I just drive and wait to see if that did the trick. Also, the elbows on the PCV look fine.