Problem after engine changeout, 99 Neon

Discussion in 'Neon' started by CenturyTek, Oct 7, 2004.

  1. CenturyTek

    CenturyTek Guest

    I completed the change a couple days ago. Vehicle starts, runs fine. After
    15-20 minutes on the road the speedometer becomes erratic, fluctuating
    rapidly up and down, eventually after about a minute, settles to zero, where
    it remains until the vehicle is stopped and allowed to sit for a while. The
    auto shifting becomes irregular after the speedometer with higher than
    normal revs being required when it does finally change.
    A 30 minute cooldown period allows the vehicle to perform correctly for
    about another 15-20 minutes at which time the erratic behavior happens
    I have seen posts indicating the eeprom might need a reflash.
    Does anyone have any ideas about this problem?
    CenturyTek, Oct 7, 2004
  2. CenturyTek

    Mike Guest

    There is definately something with your computer/sensors. I know that
    until the engine reaches running temp, there are verious sensors that
    are set to open circuit. I do not know the whole list of them other
    then the O2 sensor, which would not cause that issue. The engine you
    put into the car, was it the same as that that came out? If the
    transmission and engine type are not the same as what the ECU was
    programmed for, this would be your issue.
    Mike, Oct 7, 2004
  3. Sounds like a speed sensor problem, or the connections to it. Did the
    transmission get changed with the engine or is it the original? When I
    had my transmission rebuilt almost two years ago, something happened
    to the sensor as a result of the transmission removal/installation.
    The speedometer was erratic, or inoperative. I probably should have
    gone back to the original shop to have them make it good, but I did it
    myself in the interest of time.

    -Kirk Matheson
    Kirk Matheson, Oct 7, 2004
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