Is it normal for the RPMs to go down

Tiny
WALLEYE08
  • MEMBER
  • 2000 FORD F-150
  • V8
  • 4WD
  • AUTOMATIC
  • 132,500 MILES
132500 miles, Is it normal for the rpms to go down then come back up then go back down when I am braking? Because I noticed when I was braking that it went down to about 600 rpms then went up to about 800 rpms then it went back down when I was braking.
Saturday, August 15th, 2009 AT 5:07 PM

4 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Does this happen when you are pumping the brakes or if you keep your foot on the brakes, does it do it? Also, has the check engine light come on?
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Tuesday, April 6th, 2021 AT 12:44 PM
Tiny
WALLEYE08
  • MEMBER
  • 4 POSTS
It does all of the time it does not make a difference if I am pumping the brakes or not. And my check engine light is on, but it has been on for long time so I dont know if it is on for this or not.
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Tuesday, April 6th, 2021 AT 12:44 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Based on what you have described, it sounds like there is either a bad throttle position sensor or idle control valve. If the light has been on, take it to a nationally recognized parts store and have them scan it to determine which one it is. Most will do it for free so there is no money out of pocket.
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Tuesday, April 6th, 2021 AT 12:44 PM
Tiny
WALLEYE08
  • MEMBER
  • 4 POSTS
It was the fuel pump, all set
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Tuesday, April 6th, 2021 AT 12:44 PM

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