Need Help With P0174 Code Please

Discussion in '1996 - 2004 SN95 Mustang -General/Talk-' started by justadodgeman, Feb 23, 2014.


  1. justadodgeman

    justadodgeman Member

    Joined:
    Jan 27, 2014
    Messages:
    37
    Likes Received:
    0
    Trophy Points:
    7
    Ive got a mustang gt that runs great and idles great until the cel pops up then it idles like crap and im not sure how a lean miss sounds but im pretty sure that's what it is. I can delete the code then drive it for maybe 30 miles, shut it off, and turn it right back on and the cel pops up and immediately it starts to idle weird. heres what ive done to try and figure out this code.
    -cleaned MAF (I think it would cause P0171 and P0174 anyways)
    -Replaced all hoses
    -sprayed brake cleaner all around intake and hoses(no change in idle)
    -blew cigarette smoke in intake and did find a leak but I don't know what the thing is called and if it is supposed to let air out or not ill post a pic of what im talking about
    -switched o2 sensors to try and through the p0171 code
    -unplugged each fuel injector one at a time to see if it changed the idle and they all did so that's a good sign
    -new fuel filter
    so what else should I check
    41120-image-02.jpg
    ignore the other circles the leak is coming from somewhere around the thing with the arrow pointed to it
    #1
  2. Thatsweetstang

    Thatsweetstang Active Member

    Joined:
    Nov 4, 2013
    Messages:
    103
    Likes Received:
    7
    Trophy Points:
    29
    Location:
    Ca
    That's your egr, your gasket could be bad that connects it to plenum/tb. Or the vacuum line that goes to it. That code usually pops for a bad o2 sensor.
    #2
  3. justadodgeman

    justadodgeman Member

    Joined:
    Jan 27, 2014
    Messages:
    37
    Likes Received:
    0
    Trophy Points:
    7
    I switched front o2 sensors to see ifit would through a p0171 code and it didn't so im pretty sure they are good and thanks for info about the egr valve
    #3

Share This Page