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Rough Idle and P0171 Code

  #1  
Old 02-18-2008, 09:11 AM
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</>Hi,


I have a 2000 Mercury Mysticle 4cy 2l. I am having rough Idle with P0171 code problems (check engine light on). I have looked at many discussion treads on this subject and understand the problem to be lean bank 1. I have cleaned my MAF with electrical spray (carefully!!). I replaced my fuel filter. The problem still exists. The other day the car actually stalled out on my (at low speed). I managed to get it going again after retrying several minutes later. I still need to check for vacuum leaks on the air intake hose - does anyone have a good picture for reference? I'm working off of a haynes manual which can be a little hit and miss. Also any other suggestions on things to try (short of take it to a garage for detailed diagnosis - which I'm getting close to as it seems like the sensible thing to do to avoid costly guesses!).


Thanks in advance !</TD></TR></T></TABLE>
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  #2  
Old 02-18-2008, 11:29 AM
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sounds like bad o2 sensor and possible idle air contrlo valve is dirty or going bad.. how many miles on the car?
 
  #3  
Old 02-18-2008, 01:02 PM
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Hi,


I think I originally posted in wrong section !


Thanks for the info. The car has 87k miles. My appproach has always been to try and confirm bad parts to save expensive swap outs. Is there a way to test the o2 sensor? Also with respect to the idle control valve. Can I just give this a clean or am I looking at a replacement?


Your help is appreciated!






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  #4  
Old 02-18-2008, 01:27 PM
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can be cleaned up. usually gets restricted from carbon build up and such. o2 sensor is what tells the computer how the fuel mixture is. so if o2 sensor is showing less air and more fuel it will try to compensate and adjust itself.. running lean means not enough fuel and too much air on that bank of the engine.
 
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Old 02-19-2008, 02:41 PM
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Thanks for the inof. I will give it a try.
 
  #6  
Old 03-17-2008, 09:48 PM
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I had the same code...turned out to be a bad maf sensor...if the other things didnt work unplug the MAF sensor and see if it hesitates
 
  #7  
Old 04-06-2008, 10:41 AM
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Hi Vic


Finally got round to working on my car again!


I checked the idle air valve and looks clean and solenoid ohms out okay. I picked up an OBDII scanner. Regarding my O2 sensors. What voltage response should I be seeing from the sensors to confirm whether they are good/bad?


Surf, I diconnected MAF and still idles rough.
 
  #8  
Old 08-31-2008, 10:57 PM
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I know a great trick for vac leaks.


use a hand heldpropane tank. put a rubber hose on the end of it, about a foot long. with the car running. open the propane valve and let the propane out around the vac lines. if the car starts to run smooth when you spray it on a certain line, then you have a bad line with cracks on it. the prop[ane is actually a fuel and will make the car run better when sprayed into cracked vac lines. this is a very cool and easy trick that will save you hours on finding that leak.
 
  #9  
Old 11-17-2008, 01:24 PM
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Fixed it ! It was a bag vacuum pipe from the egr to the inlet manifold. Thanks for everyones assistance !
 
  #10  
Old 12-11-2008, 01:20 PM
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just was reading ur guys and seems have same problem so if theres more air then fuel how do u fix that
 

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