97 Expedition

Discussion in 'Other Auto Tech' started by COramprat, Jun 17, 2007.

  1. Took a little trip this week and when I gave my Expy some gas to pass, the RPM's would run up like it had dropped into 3rd but would slow like I had a tranny slipping. With the cruise on the engine would jump from 2 grand to 3 on an incline but would actually slow speed wise. I'd have to disengage the cruise and just hold steady pedal to keep it at an agreeable speed and slowly get it up to the speed limit again . Getting on an on-ramp was like pedaling a bike in a head wind. Just had to take about twice the normal distance to get up to 70 since it would not accelerate at all at WOT and was very sluggish at 3/4.

    Moderate acceleration in town traffic it would do fine. Drops into lower gear and moves along OK...but when going past 3/4 it peters off. Also have two codes...PO171 and PO174. Not sure if these are related to the problem.
  2. Yea...I've found the post on why I may be getting the codes but it doesn't seem related to the drivaibility issues. :shrug:
  3. A lot of OBD-II scanners won't pull the transmission codes. You'll have to either find a buddy with one of those Snap-On scanners, rent/buy a high-end OBD-II scanner that specifically lists code-scanning capability for transmission codes, or have a dealership pull the codes for ya'.

    It could be something as minor as a sensor of some kind throwing off the tranny, since most new automatics are electronically controlled - hell, even a bad plug wire can screw with your shifts, sometimes (it did on the 4.6L Crown Vic, Cougar, and T-Bird that I've owned) - but it might also be something more severe.

    Is your "O/D off" light blinking? If so, that's an indication that you've got stored tranny trouble codes.
  4. No other indications other than the two check engine code. I reset them just ot see if they come back. So far nothing...

    Someone suggested a clogged cat. That may explain the codes but I'm not sure if the drivability issues could be related. I do have some hesitation but I attributed it to whatever is causing the power drop.
  5. p0171 and p0174 are lean codes. first things to check for with your symptoms would be a fuel pressure drop or a misfire.. ( misfires can lead to a lean code because the 02 sensors pick up the unburned oxygen and assume that the mixture is lean)