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Thread: Car slows for a split second every 3 seconds

  1. #1

    Default Car slows for a split second every 3 seconds

    I'm not sure what is going on... I have noticed this for a while now, but it seems to be getting a little worse. I notice it most at 45mph and above. Approx every 3 seconds my 1989 GM seems to slow for a split second... almost like the brakes are applied for just a split second. Just curious if anyone else has experienced this before. Also, it seems to be the same whether I am in OD or not.
    Also, I don't have internet at my house anymore (Provider (Cricket) trying to make me upgrade my phone, which I won't do) so It will be a few days in between checking messages.
    Thanks in advance.
    Eeic

  2. #2
    I'm an air-conditioned gypsy gadget73's Avatar
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    do you have the AC or defrost turned on? Sounds like the AC compressor engaging and disengaging because its either low on refrigerant or its just not warm enough. Turn the climate control completely off and see if it stops.

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  3. #3
    all the CFI are belong to me
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    Quote Originally Posted by gadget73 View Post
    do you have the AC or defrost turned on? Sounds like the AC compressor engaging and disengaging because its either low on refrigerant or its just not warm enough. Turn the climate control completely off and see if it stops.
    I will +1 this. My 84 cycles the low pressure switch and when you get those extra ponies back for a few seconds, you notice it.

    Another possibility, though it may seem unlikely, is sticking brake calipers, but you would have a pull that went to one or both sides alternately. I drove my 83 with sticking calipers (which eventually resulted in a grease fire on the ball joint) and after they got pretty hot they would pulse. It's worth checking if you aren't using an AC mode at the time it happens.

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  4. #4
    GMN Regular DerekTheGreat's Avatar
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    LoL I will x3 this!

    Reminds me when we were driving through Florida the first time and I felt what seemed to be a jerking or tug at the back of the car every few minutes or so. Kinda felt like a misfire and I was about to start freaking out when I just decided to turn the A/C off. Jerking went away and I deduced it was the A/C compressor engaging. Wow.
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  5. #5

    Default

    Quote Originally Posted by gadget73 View Post
    do you have the AC or defrost turned on? Sounds like the AC compressor engaging and disengaging because its either low on refrigerant or its just not warm enough. Turn the climate control completely off and see if it stops.
    Thanks! That just might be it... The AC was not on, and everything was in the off position, but the fan selector was on Auto. I remember hearing a funny noise the last time I had the hood open and the AC compressor was definitely the culprit... I can't exactly recall the sound, but it did not sound proper, lol... sounded like ball bearings rattling around from what I can remember. The AC worked when I bought it, but that was over 6 months ago now and a lot can happen in that time.

  6. #6

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    Quote Originally Posted by kishy View Post
    I will +1 this. My 84 cycles the low pressure switch and when you get those extra ponies back for a few seconds, you notice it.

    Another possibility, though it may seem unlikely, is sticking brake calipers, but you would have a pull that went to one or both sides alternately. I drove my 83 with sticking calipers (which eventually resulted in a grease fire on the ball joint) and after they got pretty hot they would pulse. It's worth checking if you aren't using an AC mode at the time it happens.
    I was kind of thinking this as well as my rotors definitely are slightly warped, but the AC compressor will be the 1st thing I check.

  7. #7

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    Quote Originally Posted by DerekTheGreat View Post
    LoL I will x3 this!

    Reminds me when we were driving through Florida the first time and I felt what seemed to be a jerking or tug at the back of the car every few minutes or so. Kinda felt like a misfire and I was about to start freaking out when I just decided to turn the A/C off. Jerking went away and I deduced it was the A/C compressor engaging. Wow.
    It has been windy, so I kind of ignored it myself, but I started paying attention and it was happening at regular intervals, and I was getting a little concerned myself... I was worried it was a transmission problem.

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