Runs fine with scanner? | Ford Escort Owners Association (FEOA)
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Runs fine with scanner?

Discussion in 'ZX2 1998-2004 2.0L DOHC' started by Texaszx2, May 27, 2019.

  1. Texaszx2

    Texaszx2 New Member

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    Has anyone ever encountered an issue where your car hesitates, but runs fine if you plug in and drive with an obd2 scanner? I get a code that's p1633. Anyone?
  2. steve60tuesday

    steve60tuesday FEOA Member

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    Over the past month I've done a lot of driving with various intermittent engine issues caused by--I think--intermittent PCM problems due to waterlogged/damaged/haunted wiring harness(es). I wondered if having the OBDII scanner connected might affect performance, but after several gas tanks of driving (some with scanner, some without), I can't tell the difference.

    From limited online reading, it appears that both the PCMs and their wiring harnesses are quite fragile. Any knowledge you might have about probable damage could be helpful. Has the car experienced electrical trauma that could damage the PCM? E.g., botched jump start attempt, recent welding repairs, contact with power lines, or government space ray damage? Similarly, have there been conditions that might degrade or damage the wiring, such as flooding, heater core leak, rodent infestation, extensive mechanical work, or you park near the ocean? Such knowledge (or evidence thereof) might help direct your diagnostic efforts.

    Good luck.
    zzyzzx likes this.
  3. Defunct SR Owner

    Defunct SR Owner FEOA Member

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    I believe part of my problems began when I removed the IM when repairing a damaged head. The wire for the IAC was likely broken when I tried moving it out of the way.

    Doom on me...
  4. Texaszx2

    Texaszx2 New Member

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    Mine is a definite fix with scanner installed, it reads real time data so I plugged btt in with hopes of finding the issue, and noticed my car stopped the hesitating. Soon as I unplug it it starts up again.
  5. Defunct SR Owner

    Defunct SR Owner FEOA Member

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    Perhaps the scanner is completing what is otherwise a broken circuit; many sensors are wired to other sensors. Do you have a wiring diagram? If so then check which sensor are in the same logic loop and check all of the wires.

    In my case the IAC is an isolated circuit and easier to diagnose
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  6. Swift

    Swift FEOA Donator

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    Take a look at you obd connector, when my Dad had his vehicle go through emissions some years ago the tester bent some of the pins.
    zzyzzx likes this.

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