98 2.5L 5sp rpm won't decrease during shifting - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 03-04-2011
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98 2.5L 5sp rpm won't decrease during shifting

I have a 1998 Ranger with a 2.5L 5 speed tranny. My problem is while the clutch pedal is pressed in during shifting (foot off of accelerator) the engine rpms never decrease. IAC valve has been changed,no codes thrown. Any help is appreciated.
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Old 03-05-2011
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Vacuum leak somewhere.
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Old 03-05-2011
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This is a normal "dashpot" function of the IAC motor. The engine will retain its RPM during shifts to reduce emissions.

A dashpot is a mechanical device, a damper which resists motion via viscous friction. The resulting force is proportional to the velocity, but acts in the opposite direction, slowing the motion and absorbing energy. It is commonly used in conjunction with a spring (which acts to resist displacement).
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Old 03-05-2011
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a bad pcv valve will cause high revs in between shifts and will not throw a code.
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Old 03-05-2011
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If you want to determine if it's the "dashpot function" or another problem, you can disconnect your VSS sensor in your dash. Can't remember what color wire it is. But if you do it right, your speedo wont work either. The GEM won't think you are moving so the motor decreases RPM immediately. I found this out while recalibrating my speedo.
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Old 03-05-2011
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I've noticed mine will do that if i have the a/c on. But the rpms drop when i do'nt. Not sure if thats the norm or not just norm for my truck.
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Old 03-07-2011
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Thanks for all the help.Found the pcv valve dislodged from oil separator.Problem rectified!!
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Old 03-07-2011
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Icon14

glad you got it sorted out

Quote:
Originally Posted by jettech View Post
Thanks for all the help.Found the pcv valve dislodged from oil separator.Problem rectified!!
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Old 05-05-2011
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Could you post a PIC , where to find the PCV valve, my ranger 97 , had the same problem.
Thanks in advance
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Old 05-06-2011
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the pcv valve is directly underneath the intake manifold driver's side of engine
just look and you will see it.
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Old 05-12-2011
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Mine has been doing the same thing.. Also missing a little bit, i will have to check this when i get home
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