In my 2008 F150 with 108,000 miles, I am having a vibration in the brake pedal. When I am stopping or at a dead stop. I first thought it might be the rotors needing to be turned, but the vibration seems to go away when I turn off the a/c.

Any ideas??

 

when you turn on the air conditioner, the clutch locks up and the compressor starts turning. I doubt the compressor has a vibration. I would guess the extra load of the compressor slows the motor RPM down 50 RPM and the motor is running a little slow and you feel the imbalance. When you are setting idle, turn the AC on and feel the vibration... then push the gas pedal down a little so the motor speeds up 100 RPM and see if the vibration goes away.

 

I will try that tomorrow.

 

There is supposed to be some device to add throttle when the compressor kicks in to maintain proper idle speed. This was a mechanical system in the old days but is a program now. If the compressor slows the idle there is a problem.

 

Vibration in the pedal typically means the rear rotors are warped, resurfacing should run. $15 to $25 for each rotor

 

Rotors will not vibrate at a dead stop.

 

Thanks for that captain obvious. How bout we just provide information that may help the situation

 

I just went for a drive, and it seems like the RPMs get too low and the vibration starts. According to my tach it's getting around 600 RPM and then it starts. These trucks don't have IAC's so could it be TPS?

 

Novuswsr, welcome to FTE. Being new here you might be pleasantly surprised to find that FTE isn't like a lot of other forums where people post in an abrasive, condescending, or flaming manner.

Your post that I quoted in bold above fits in the category of abrasive and condescending. Yeah, I know, I'm being obvious....(pun intended)

Keep it easy-going when you post bud. We like to enjoy our tech forums, not foment or stir up negative emotions. In the vernacular of todays younger folk, that aint how we roll, here.

Now, all of that aside, your Captain Obvious post really missed the target. CritterF1 pointed out something that you completely missed in the OP's first post.

Here, I'll highlight it below for ya, in the re-quoted post:

So as you can see, critter was pointing out something you had missed when you posted up for the OP to have his rotors turned.

Sometimes, even OBVIOUS things in a post still need to be pointed out.

Critter (Captain ) thanks for pointing out what was missed. You can ask the guys in the Ex forum, I have a really bad habit of glancing over/speed reading a post, so I miss stuff like novu did here in this thread.

Stewart

 

Points well taken, thanks

 

Stewart

 

Is there a way to fix the rpm problem?