Really Fast idle in park and neutral only
05-07-2009, 07:06 PM
#2
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Could be a few different things but two of the most common are a vacuum leak and/or a bad IAC (idle air control valve).
How high is the idle? Check Engine Light on?
I have a 93 with the 4.9L and a manual tranny and mine idles about 250-300 rpm high. I am still hunting the source of my problem though.
How high is the idle? Check Engine Light on?
I have a 93 with the 4.9L and a manual tranny and mine idles about 250-300 rpm high. I am still hunting the source of my problem though.
05-07-2009, 11:52 PM
#3
Check for codes, this thread explains how: https://www.f150forum.com/f10/how-retrieve-trouble-codes-obdi-10907/ Possible bad park/neutral switch which tells the computer when the truck is in park or neutral so it can lower the idle.