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Bucking when stopped

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by scotthershall, Jul 10, 2012.

  1. scotthershall

    scotthershall New Member

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    Good evening all,

    I've been lurking around here for a while, but here's my first real issue.

    After I start my car and put it in D, car stopped and foot on the brake, I can feel the car bucking a bit. It only happens when the engine is cold, and it goes away after a half mile or so of driving. I notice it the most when I'm leaving work in the evening - start car, drive 50 feet or so, and am waiting to pull out into traffic. Its pretty subtle as if someone is giving the car a gentle nudge. No drivability concerns other than this. It's done it since I got the car around 43k miles about 18 months ago. The car currently has around 67k.

    Is it normal? Anything to be concerned with? Any possible causes?

    Thanks folks,

    Scott
     
  2. PriusCamper

    PriusCamper Senior Member

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    Mine runs rough when cold too... Also sometimes when cold and engine turns off at stoplight it starts dieseling, as in engine turns off but it keep going a little longer. Researching on here I found out that it's a recall issue with the intake manifold on the Atkinson engine and if you're still under warranty they'll replace your intake manifold with a better one but you have to complain beyond all the excuses they give you to keep you quiet. Earlier today I read that the GenIII has the same problem? Or maybe I've confused the two generations? Regardless, I'm willing to bet it's yet another reason why whoever owned my car before was so fast to sell it as soon as their 100,000 mile extended warranty was up.
     
  3. cwerdna

    cwerdna Senior Member

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    Sounds normal to me. There are a bunch of threads on the rough ICE shutdown on the Gen 2.

    Google for site: priuschat.com rough shutdown (remove the space between the : and p).
    Source? I think you're totally confused. I think you're talking about Toyota announces service campaign to fix exhaust on 28,000 Prius V hybrids which is only the the Prius v wagon, NOT the Gen 2 or 3 liftback.
     
  4. edthefox5

    edthefox5 Senior Member

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    The throttle body & maf need to be cleaned.
     
  5. scotthershall

    scotthershall New Member

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    Thanks for the replies so far.

    Just to clarify, the engine is running when I feel the bucking (in warm-up mode). It's pretty rough when it shuts down too until it's fully warmed up, but I know that's relatively normal.

    Yeah, cleaning the throttle body and MAF seems like a good suggestion. When I changed the air filter when doing the 60k maintenance, it seemed to be a lot dirtier than I expected (for any car let alone one whose ICE doesn't run all the time). I suspect the filter wasn't changed at the 30k maintenance interval. I'll have to do some research on cleaning the MAF. I know some MAFs can be super sensitive. Hopefully a can of electrical parts cleaner will do it.

    Side note: about 50 to 75 miles after changing the air filter (and adding a can of Chevron Techron fuel system cleaner) during the 60k maintenance, I got a CEL. It went out about two days later. I attributed it to car having to adjust the fuel/air mixture due to the restricted airflow with the dirty filter. I didn't bother pulling the code to find out what the problem was.

    Scott

    Edit: spelling
     
  6. edthefox5

    edthefox5 Senior Member

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    They sell a spray can of cleaner specifically for MAF's in the auto parts store. Search back my old posts I have a very detailed post about cleaning both TB & MAF including tools needed. Its pretty easy. Also in that post is a method to clean the Variable Valve Timing oil filter.
    I found the bucking lessens alot with Mobil 1 oil in the engine and it gets less and less as the car gets older.
    With the CEL check all fluid levels carefully. You may be low on oil.
     
  7. scotthershall

    scotthershall New Member

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  8. edthefox5

    edthefox5 Senior Member

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    Y thats it. I like the long cloth strip thing to clean the TB. Cleaned many a TB and that system works really good. It prevents alot of the cleaner fluid from getting into the intake and cleans very thoroughly.
    Good Luck!
     
  9. AZDriverMan

    AZDriverMan Member

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    My Prius also does a "bucking" when stopped sometimes. It does not matter if the engine is "hot" or "cold." Do you think servicing the MAF and the throttle body will work? I have also read that sometimes the PCV valve can cause rough engine idle. It is not only when stopped, sometimes the Prius will have a hard time accelerating (will hesitate sometimes, and will use more power than usual to accelerate). I have checked the 12V battery and all the voltages are reading normally (while on and off both).

    Also, I have noticed when the ICE is on, when I go from drive to park, the engine will usually jump. It is almost as if the ICE tries to shut off yet does not. It almost bucks or "jolts." Is it normal for a Prius to "jump" or buck when going into park when the ICE is on? It sometimes jumps a little going to park, although it is far less often than when going into park.