Okay so here goes, My 03 recentally just threw some codes. P0171, and P0174, Syetem to lean bank one and system to lean bank 2 i belive, i dont have them written down in front of me. Also i am getting really ****TY gas mileage. I used to be able to go right at 150 to a quater tank of gas, this go around it was excatally 154 to half a tank. Engine runs fine and idles nice and smooth. Tune up last summer whole 9 yards. Cleaned the MAF mid december along with the throttle body. I did just spay down the tube. I cleared the codes and the light has stayed off but im still seeing the crappy mileage. Any insight would be nice. Thanks.

 

how many miles are you at? Sounds like front O2 sensors are on their way out

 

faulty 02 sensors do not set lean codes, especially both banks at the same time...what they DO is tell you your running lean. You either have a lack of fuel pressure or a vacuum leak. Most probable is vacuum leak.

 

Thats what i was thinking. I got some intake cleaner and started spaying everywhere while the engine was running. No change in rpms ever. I spayed all lines alll around the intake in the back by the pcv valve nothing. Then I took off the intake tube in looked up inside and it looked as if water had been slpashed up in there. So i took the intire assemblly off fender to Throttle body and cleaned it good. Iat and maf everything got a through cleaning. Went to the parts store cleared the codes and hasnt set anything off yet. Im thinking something got onto the MAF, im not sure about my mileage yet tho havent drvin enough to tell if its back to normal. Thanks for the replys guys ill keep ya posted on the mileage.

 

Okay am I missing something here. NO engine light or codes present. Truck runs like dream, ALL mantaince done. Tires propely inflated. Yet im still only getting 100 miles to a quater tank compared to my 150 i ussally get. Also i keep my foot off the gas as offten as i can and drive senseable. Im at a loss here guys, anyone got anything to add?

 

Hi

I am chasing the same codes. Sometimes it takes 2-3 weeks for my codes to reappear after I clear them.

Harry

 

even though your codes may not be re-appearing the lean condition may still be present and hasnt hit the threshold to flick on the light. The only way to know for sure would be to bring it to a shop that can monitor your fuel trims and see if they go high positive anytime you are driving it. If its compensating by dumping in extra fuel to keep your A/F ratio in spec it will make your milage go for crap.

 

Went down to the ford dealer today and had a chit chat with them. Found it it is 99.9% sure its the intake gaskits inside the intake pleumm. Im droping back by tomarrow to pick them up along with the bolts. Lucky the federal gov gave me some money back so i can afford to buy the 140 dollar kit. Probely gona get to changing them this weekened. Will keep yall up to strach with what devolps.

 

Okay so i have changed my intake gaskits and im am sad to say im still getting bad mileage. Im at my wits end. 15mpg. Yeah i know that sounds the norm for some but it dont explain the 18 to 15mpg drop. Whats everyone think about the thermostat being stuck open? Or maybe even the cats clogged?

 

Winter blend fuel. You could try changing the front O2's. If the stat were stuck open your temp gauge wouldn't come up to the middle. If the cats were clogged, you could rev it up and feel the exhaust at the tailpipe, and it would be weak.

 

Winter blend fuel shows up in my gas mileage big time.

Bring on the warm weather & it's much better gasoline!

 

Dave, get out of the KC metro area into more rural KS and buy gas with no ethanol. The KC area's winter blend is 10% ethanol and is terrible. Your metro summer blend isn't much better. ALL gas in MO is 10% so if you are going over there to get cheap gas you are getting what you pay for.

 

The thing i wonder is how come i wasnt getting bad mileage back in nov dec and jan, Feb came along and thats when it started doing it. 300 miles to the tank this go around and it was ALL highway. Guys there has to be something going on here.

 

I have the same truck with the same engine, and its the same year. Unfortunately, I have the same problem. I tried cleaning everything, talked to the dealership and got no answers. I ordered another code reader that can monitor some of the systems like emissions and fuel to see if I can finally figure it out, or get a better understanding of what is going on with the truck. Sears is supposed to have it to me by tomorrow.... I know what you are going through, and if I find anything out with my truck, then I'll pass it on to you.

The problem is there are so many things it could be. When I went to the dealership, not only could they not answer my questions, but they showed me the book with codes and possible causes. For the p0171 & p0174, it was about a page in length for possible causes.

FYI: I don't know if your truck is like mine (what a dumb statement) my truck didn't have a pcv valve, it was just an elbow. I have no idea, but that was where the pcv was supposed to be.

 

We drive FORD trucks...whats gas mileage?