Ever since I've had my 99 Ford KN Laser Auto, I've been plagued with idling issues. When I first got it, it was barely idling at about 500 RPM. I've replaced the plugs, TPS and crank sensor after it shorted out. Now it usually sits around 8-900, except when it doesn't.

At cold it idles at 1500 and doesn't come back down once the engine warms up. However if I cut the motor and restart it, the idle drops back to 8-900. Likewise when driving, sometimes I'll notice the engine running on when my foot is off the accelerator, when I drop it into neutral it's idling at 1500. If I cut the engine and restart it, it returns to back to 8-900.

Any idea what might be wrong with it?

  • Does the car have an OBD port? If so, have you read the codes? Jun 5, 2021 at 23:06
  • Confirm that the coolant temperature sensor is working.
    – Jupiter
    Jun 5, 2021 at 23:12
  • @DavidSupportsMonica, I went down the OBD2 rabbit hole once before and as far as I can tell these Lasers use something else. reddit.com/r/cars/comments/1pl8tl/… fordlaser.com/forum/viewtopic.php?f=2&t=88630
    – Ian Oakes
    Jun 6, 2021 at 8:11
  • @Jupiter, good point but the temperature gauge seems to work just fine. When you start car with a hot engine it idles just fine, until it doesn't, and then you have to 'turn it on and off again'
    – Ian Oakes
    Jun 6, 2021 at 8:13


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