2003 Sport track p0171 and p0174 CEL Codes

[kev7554]

Ok my CEL came on a couple of weeks ago so I took it and had the codes pulled off and they were P0171 and P0174. Tech said to replace both Oxygen Sensors. I didn't have the money so I just drove without fixing and everything seemed fine. Yesterday when i went to start it it was tough to start and stalled a few times. Also when at lights or stop signs it almost stalls and sometimes does. So I did some online research and found out that its usually never the o2 sensors. So I looked for Vaccum leaks and I found a pretty big one. Went and purchased the new rubber hose/boot from ford and put it on.

Had the codes cleared at autozone and thought the problem was fixed. Well half way home from autozone the light came back on and it seems to be idling rough again. I also noticed that when i rev the engine it gets to about 3000 RPMs and it starts to stutter REVS HIGH then low High then low no matter how far down i press the pedal it gets to 3000 and wont go any higher. So does anyone here have any ideas what to check next or should i just replace the o2 sensors. Thanks in advance

 

[John_Rock]

I also noticed that when i rev the engine it gets to about 3000 RPMs and it starts to stutter REVS HIGH then low High then low no matter how far down i press the pedal it gets to 3000 and wont go any higher.

That's the computer keeping you from over revving your engine when there is no load on it.

 

[gguerra]

I had the same codes on mine and the same problem (rough idle) and it ended up being a faulty vacuum hose. The guy at the shop found the problem right away using one of their diagnostic machines. There are other causes but I would check the obvious first before spending a lot of money. Another common cause is the MAF sensor. Check out this page for more info http://www.aa1car.com/library/ford_lean_codes.htm