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Old 03-16-2011, 11:14 AM   #1
charlie.cross2
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p0171 (system too lean, bank 1) wont go away...

Hey all,

So I've been dealing with this code p0171 (system too, lean bank 1) for around 1250 miles now. I originally suspected the o2 sensors as i had about 125k on the car. Changed out both upstream and downstream sensors. Also changed the wires, plugs, fuel filter, air filter for good measure. The code didn't go away after the o2 sensor change, so I erased the code with a scanner tool thinking maybe it just needed to be reset. Well it came on again after about 100 or so miles...

After some inspection I noticed the number 1 plug wire was shaking, and when I pressed on it with the engine on, I got a slight puff of white smoke and a tick tick tick.. I pulled the wire and plug; it seems like the plug wasn't all the way secure (also about 1/4 of it was black... I dont know if it was because it was loose or) so after tightening it car ran well. I decided to erase the code again...

This time it stayed off for about 500 miles and allowed me to pass emissions... About a week ago though it just popped on again!

I've been researching and took a look at my pcv hose for cracks etc. It was recently replaced and looks great. The valve itself looks burnt and very dirty, but it clicks when shaken, I've heard that meant it was ok still.

I've heard from other people this could be an injector issue... I took a listen to the engine and I hear a distinct tick tick tick from around the fuel rail. Could it be a faulty injector? I'm pretty much stumped at whats causing this code. Thanks for[reading!


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Old 03-16-2011, 12:28 PM   #2
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OK Maybe this will give you an idea of where to look.

P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:
Fuel system
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Induction system:
Air leaks after the MAF.
Vacuum Leaks.
PCV system.
Improperly seated engine oil dipstick.
EGR system:
Leaking gasket.
Stuck EGR valve.
Leaking diaphragm or EVR.
Base Engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
A SHRTFT-1,2 PID value between -25% to +35% and a LONGFT-1,2 PID value between -35% to +35% is acceptable. Reading beyond these values indicate a failure.
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Old 03-16-2011, 11:07 PM   #3
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Thanks for the info! That's a ton of stuff lol. I think i'm going to try visibly inspect the injectors, see if the o-rings are leaking etc.
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Old 03-17-2011, 11:21 AM   #4
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you wont be able to see anything wrong with your injectors although dirty injector can and will throw a p0171. does the car idle rough ever? also even if your pcv still rattles the hose could be sucked shut
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Old 04-06-2011, 12:04 PM   #5
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Pcv valve!

Hi,

Just been dealing with the same thing for 3 weeks, Changed both O2's and a bunch of other stuff. I was convinced that I had a vacuum leak.

SOLVED!!!

$1.99 PCV valve from autozone put in and No code anymore, Idle drop gone as well.

Start there. I am going to buy a PCV from ford, the autozone one is suspect as far as quality.
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Old 07-31-2013, 05:03 PM   #6
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Quote:
Originally Posted by SonicPDX View Post
Hi,

Just been dealing with the same thing for 3 weeks, Changed both O2's and a bunch of other stuff. I was convinced that I had a vacuum leak.

SOLVED!!!

$1.99 PCV valve from autozone put in and No code anymore, Idle drop gone as well.

Start there. I am going to buy a PCV from ford, the autozone one is suspect as far as quality.
So I also have the same code and such is it really something I should be concerned about.. and how is the one you ordered from ford. Was it pretty simple to install ?
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