My 91 Nissan Sentra 1.6 fuel injected engine has recently experienced a fast idle problem. I have no tachometer, but I can tell its a few hundred rpms faster than it should be, like it's running when it's cold. Could this be my fast idle control valve? They are kind of pricey, so I want to be sure before I replace it. This car has been great and has 211K trouble-free miles on it. Any thoughts to what the problem may be?
I would find a shop that had a Motor Vac machine to de-carbonize the intake and throttle body.
If your willing to gamble on a little of your time try doing what I suggest below.
What I would do first is clean the throttle body and the idle speed control motor. I bet it has never been cleaned and this could be the whole problem.
If it gets dirty enough it will increase the idle speed and cause the Idle Speed Control Motor NOT to move quickly enough or smoothly.
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