Overdrive

Discussion in 'Drivetrains' started by Emdog, Mar 3, 2011.


  1. Emdog

    Emdog New Member

    Messages:
    19
    Likes Received:
    0
    Trophy Points:
    0
    I have a 91 ford escort lx automatic transmission. i noticed that there is no noticeable difference between drive and overdrive. i had a 95 and there was a difference. I don't have any other transmission problems besides a acceleration issue but i believe that is just a bad injector. Anyone have any ideas, i read the codes just a air temp vane code and i just replaced it. Also i know this has nothing to do with the topic but does anyone know the size of the gas tank that this year and model has.

    I have researched other problems with other cars and they say computer.
  2. denisond3

    denisond3 Moderator Staff Member

    Messages:
    5,286
    Likes Received:
    449
    Trophy Points:
    283
    Location:
    south TX or northern VA
    I think the fuel tank on all of the 2nd gen. LX's was the same; 11.9 U.S. gallons. I once put 12.1 gallons into my 92, having driven it till it was empty on purpose; then filled it up till the fuel filler neck was also full.

    Also I believe the automatic transmissions would be the same for a 91 and a 95, the F4EAT. The transmission control module is a separate item on the 91, while on Escorts after about 93 that function would be incorporated into the main engine control module (aka the PCM) - but the control doctrine should result in the same shifting.
    The 91 should have 3 sensors located on the metal tube running from the lower part of the thermostat housing back toward the firewall, while the 95 would have only two of them. That 3rd sensor on the 91 is -I think- used to tell the transmission that the engine is warmed up, so it can begin using OverDrive, (the 4th gear) instead of just Drive (3rd gear). It could be that sensor is defective, has a bad connector, or even has crud blocking the water from heating it up. Im not even sure if that sensor is a thermistor or just a thermal switch.
    Of course your problem might also be other things; like the control circuit for the 3-4 shift or the solenoid on the valve body not working, or something preventing the 3-4 shift valve inside the valve body from moving.
    I think any 2nd gen. Escort with the 5-speed trans only has the two sensors. The one with two wires to it tell the PCM about engine temp, the one wth a single wire to it just operates the temp gauge on the dash.

    The good news is that your transmission is likely to last longer; since the clutch pack that does the 3-4 shift is what often wears out first on the F4EAT. I keep mine in 'Drive' when running around the suburbs - which is 95% of our driving. This saves a LOT of 3-4-3-4 shifting in the 30-45 mph speed range. I only put it into 'OverDrive' when running at steady speeds above 55, like on the interstates. Running the car in 'Drive" at 60-65 wont hurt anything. I seldom go 70 anyway.
  3. Emdog

    Emdog New Member

    Messages:
    19
    Likes Received:
    0
    Trophy Points:
    0
    Thank you, i will check them out i recently bought the car and i did notice there was a connection that connected to the transmission or transfer case. That was disconnected the guy who owned it before me redid the ground wire all the way back. So i reconnected it and i had a better acceleration at take off, maybe i need to disconnect it and clean it and then use dielectric grease.
  4. denisond3

    denisond3 Moderator Staff Member

    Messages:
    5,286
    Likes Received:
    449
    Trophy Points:
    283
    Location:
    south TX or northern VA
    The Escorts have several ground connections here and there - and I think all of them are important for something or other. I replaced that strange connector at the negative battery terminal by soldering all of those wires into one bundle, and grounding that to the new ground cable I installed, The original Escort ground cable got soldered to my new ground cable too.
  5. Emdog

    Emdog New Member

    Messages:
    19
    Likes Received:
    0
    Trophy Points:
    0
    Sorry it took so long to reply back but i cleaned all the connectors around that area just to make sure. i believe it to be about 7 or 8 connectors and it didn't change a thing.

Share This Page