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I have a 2003 Ford Escape, 2.0L, manual transmission.

I am experiencing a very strange issue.

If I am driving (moving), and shift into neutral, the RPMs will rise up to 3500 about, and stay there till I come to a stop. I am in neutral the whole time. The car idles fine, but if I shift into neutral while the car is moving (while shifting between gears), or if I shift into neutral before coming to a stop, the RPMs rise much too high. But as soon as the car comes to a stop, the RPMs return to normal...

I replaced the idle air control valve, and throttle position sensor, and there are no engine codes. I did disconnect the battery after replacing the components, to clear the computer. No vacuum leaks that I can find either... I can't imagine the connection between wheel speed and idle speed..!!

Any ideas on where to start looking?

Thanks! Ben

UPDATE - RESOLVED - Replaced plugs and wires and issue was resolved.

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  • Welcome to Motor Vehicle Maintenance & Repair!
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Sep 15, 2018 at 23:14
  • Is this a new behavior or something that has always happened? I ask because my wife's 2006 Mariner has done the same thing.l since new. It's an automatic though. What you describe would drive me nuts to live with.
    – zerpsed
    Sep 16, 2018 at 0:06

4 Answers 4

Reset to default
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Im going to bet that you did not replace the IAC with a new Motorcraft brand. There is a large batch of aftermarket ones that are causing the exact symptoms you describe. You were probably correct in replacing it, but it needs to be a Motorcraft.

I had a 2003 Ranger with a high idle complaint. With bi-directional controls, I was able to command the duty cycle in 10% increments, and the expected behavior should have been a 100-150 rpm increase for each 10%. With the aftermarket IAC valves (note that a few different suppliers were used) the rpm would jump from 800 to 1500 rpms in the first 10% and then hold that higher rpm until 50-60% was commanded and then continued to rise. With the use of a labscope, I was able to verify the PCM's duty cycle was performing as commanded with the scanner, and a genuine oem IAC was indeed the fix.

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  • Thanks for the reply! However, I had the same problem before I replaced the IAC... When I replaced the throttle position sensor, the problem became much more apparent. before, it only happened from time to time...
    – Ben
    Sep 16, 2018 at 7:16
  • @Ben- Did you replace the TPS and IAC with oem?
    – Milison
    Sep 16, 2018 at 13:06
  • IAC is replaced with HITACHI
    – Ben
    Sep 16, 2018 at 14:52
  • Can you explain why the RPMs return to normal when the vehicle stops moving? What does vehicle speed have to do with anything??
    – Ben
    Sep 17, 2018 at 2:36
  • The ECU does not command the lowest RPM until the vehicle is completely stopped. We would not want the RPM to drop to 800 between shifts. It is best to test the IAC valves ability for smooth and even operation through it's full range using a professional scan tool. -reddit.com/r/MechanicAdvice/comments/7yalkb/…
    – Milison
    Sep 17, 2018 at 12:49
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that definitely sounds like an interesting issue you have there. originally i was thinking that the vehicle was equip with shifting rpm hold and it was going on the fritz. but that seems unlikely. it doesn't sound like it would be a vacuum leak because it would idle at 3500 all the time. sounds software related to me. i would try to do a capacitor discharge. disconnect both battery terminals from the battery, wait a minute then touch both terminals together for a minute or two (WITHOUT CONNECTING THEM TO THE BATTERY). this will ensure a total reset of the computer. hopefully this helps, it has saved me a few times from some head scratching situations. best of luck to you!

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  • What is a shifting RPM hold? I am very curious about that... I did reset the computer as you suggested... .... also, after reconnecting the battery, is there anything I should do to properly re-learn the computer?
    – Ben
    Sep 16, 2018 at 7:14
  • My understanding of shifting RPM hold is basically the ecu trying to match flywheel rotational speed with the next expected input shaft speed. Input shaft speed varies based on the next engaged gear. The ecu is guessing either one above or one below the previously engaged gear; maybe with some logic to approximate whether the human will be downshifting or up shifting based on the level and direction of acceleration with the last engaged gear.
    – zerpsed
    Sep 17, 2018 at 14:15
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nothing special to re-learn, just drive normally. may be a little rough at first but will smooth out as the ecu re-learns adaptive values. shifting rpm hold is a new-ish feature on some models. i know the new manual mustangs have it. when you shift the computer will let the rpm drop to the next gear ratio and hold the rpm for a few seconds so when you release the clutch pedal it is a smoother shift

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  • Please add this as a comment to your other answer.
    – Zaid
    Sep 18, 2018 at 13:00
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Replaced plugs and wires and issue was resolved.

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