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Discussion Starter #1
I have a 2002 Ford Focus SPI. A few weeks ago I noticed the engine running rough after idling for few minutes and not to long after that the CEL came on. I took it to Autozone and the code is P0171. Since then the rough idle has got worse and the car has cut off once. I've noticed that if I turn the AC on or put it in neutral that the rough idle stops.

After browsing the forum I wanted to rule out the cheap options. I got a pcv valve and some MAF cleaner from Autozone but they ended up having the wrong PCV valve. I cleaned the MAF and also cleaned the PCV as well as making sure that it rattled when shaken. I also looked over the vacuum hoses for leaks paying close attention to the bend in the hose connecting to the PCV valve. They looked fine from what I could tell. I reset the CEL after this but it still did the same thing and after a couple days it came back on.

I initially thought my next steps were either replacing the MAF or O2 sensor. But after some more searching it seems more likely that the EGRV needs replaced due to the fact that the AC causes the rough idle to cease.

Am I going down the right path? I don't have in depth mechanical know how so I'm trying to piece together chunks of stuff here and there. Should I rule anything else out before replacing the EGRV?

Any advice is much appreciated!
 

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P0171 is SYSTEM TOO LEAN

EGR has a different code so should it be throwing it if it was EGR ?
If you cleaned the MAF then it should be fine. O2 could be an issue, but let me ask you this.

When was the last time you replaced your fuel filter ?? Did you have a fuel pump recall done on your car ? There is one.
 

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9 times out of 10 P0171 is the fuel filter, they only last efficiently for 25,000 miles...most people never change them

they are what we call "forgotten filters" in the auto parts business

the point of that code was to tell you exactly what the problem was, did the AutoZone employee not give you the code's description or advice on how to fix it?
 

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Discussion Starter #5
I’ve had the car a few months and havent changed the fuel filter so it should definitely be changed. I’ll also check for any leaks past the MAF. Would the fuel filter explain the rough idle stopping when the AC is on?

I wasn’t aware of the fuel pump recall so I’ll be calling Ford in the morning. I entered my VIN on their website when I got the car to see if but seem to remember it kept telling me it couldn’t find my VIN so maybe I was fat fingering it or something.

Yea Autozone gave me a printout with the code but they didn’t have much advice. I don’t have the printout with me but it did list several potential causes including the MAF and O2 sensor but the EGR wasn’t in the list. The AC symptom is what got me sidetracked down that path.

Much thanks for the help!
 

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yea mine does the same thing but not the thing with the ac
but im pretty sure its a vac leak
 

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Could the breather hose be the culprit? At least I think thats the name of the hose. It's the hose on the SPI that runs parallel along the back side of the valve cover and makes a u turn into the left side.

I found some cracks around the bends but I'm not sure how this fits into the equation since penguin and others said to check for vacuum leaks past the MAF.

I'll be replacing the fuel filter and this hose over the w/end but hoping this might be the problem.
 

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Ford does have an updated pcv valve for the spi engine. I use carb cleaner when checking for vac.leaks, we also have a smoke machine that works great. If you don't find the leak it maybe the pcv valve (i know you've replaced it, but the one you got from autozone may be a copy of the earlier design.) If you would like, give me your vin and I can check it out for FSA or TSB's pertaining to this problem.
 

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Well, no answer from the OP.

I replaced the pre-catalyst O2 sensor on mine, too. It did improve tractability at light throttle, but it did not make the light go out or make the code go away.

Dirtbrown, did your light go out by itself after replacing the sensor?
 

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Try changing the fuel fitler, it's easy to do...
 
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