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Acceleration Shudder

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jedi_Chic, May 3, 2015.

  1. Jedi_Chic

    Jedi_Chic New Member

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    Hi All! I have searched several prius / hybrid forums for my problem without any luck. So I may have an unusual problem. But just in case any of you have had this, any advice would be appreciated! I am afraid that the dealership techs are going to be just as ignorant as I am!

    Problem: 2006 Prius begins to "shudder" when accelerating over 10 mph
    Symptoms: The shudder feels like going over a "washboard" dirt road. It mimics the normal "cough / hesitation" that occasionally happens when the MG2 switches to the ICE while accellerating, or vice versa at a stop light. However, unlike the normal switching, this is continuous. It ONLY happens when accelerating; as soon as I lift my foot from the gas, the shudder quits. Although it is worse in stop-and-go, it is also noticeable on a clear freeway. It is worse with a cold engine, but continues from speeds of 10 mph all the way up to 80 mph (and probably higher.) The shudder is slower at lower speeds, and faster at higher speeds. It is most dramatic when making a left turn from a dead stop - the whole vehicle shakes. Weather conditions vary, but usually it happens on dry, paved roads, anywhere from 30-degrees to 75-degrees (F).
    Frequency: first noticed a few months ago, gradually becoming more frequent. Now, it is almost every time the car is started. (Sometimes it accelerates without any problem at all.)
    Diagnostics: The "Check Engine" light has been on for about 5 years (dealerships couldn't find anything wrong and it turned out to be the MG1 battery.) But when this new shuddering happens, the "Check Engine" light blinks continuously until the shuddering quits (i.e. let off the gas or brake.) There are no other indicator lights on (no triangle of death). And the diagnostics mode tells me nothing.
    Other Info: The MG2 battery has not been replaced in the entire life of the vehicle. The MG1 battery was replaced, however, about 2 years ago. Regular oil changes have been kept up, along with air filter replacements, brake pad replacements, tire rotations, and all the other standard maintenance. It has had one owner, and is at 255,000 miles. MPG is currently at about 44.4 and has not changed since this problem started.

    I love my peppy little Prius and this issue is making me nervous!
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    There is only one battery, not an MG1 and MG2 battery.

    Just the fact that you've got an acceleration symptom, that wasn't present, then cropped up, and continues to get worse, coupled with warning lights, doesn't sound good. There should be codes present if there's warning lights, get them checked out?
     
  3. JC91006

    JC91006 Senior Member

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    Did the dealer check this out? There should be dtc that will point to the problem. I'm suspecting a bad coil and you're getting a misfire and you may have an issue with your transaxle, specifically mg2.

    You need to get the codes read.
     
  4. sfv41901

    sfv41901 Masta S

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    Without having the codes read, it's gonna be a guessing game of "maybe it this" or "maybe it's that".

    VS980 4G ?
     
  5. bisco

    bisco cookie crumbler

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    sounds like your tranny is in its death throes.
     
  6. Jedi_Chic

    Jedi_Chic New Member

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    Thanks for your responses!

    When in diagnostics mode, there are no codes present. Is there somewhere else to look for codes?

    Haven't taken it to the dealership yet. Past experience has told me to go only when I have some idea about the source of the problem. ;-)

    sfv41901 - I am afraid that might be the case. :-/
     
  7. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Blocked up egr valve? Assuming the gen2 has one?

    If not, air flow meter issues?
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    Someone (maybe Patrick) said second gen doesn't have EGR.
     
  9. Jedi_Chic

    Jedi_Chic New Member

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    So there are four codes:
    P0304 - Cylinder #4 Misfire
    P0011 - "A" Camshaft Position - Timing Over-Advanced or System Performance (Bank 1)
    P0012 - "A" Camshaft Position - Timing Over-Retarded (Bank 1)
    P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Your OP says the car has logged 255K miles and you are the only owner. When were the iridium spark plugs last replaced?

    If the plugs were replaced more than 100K miles ago, start by doing that. Inspect the spark plug coming out of cylinder #4 in particular (this is closest to the driver's side fender).

    The two Prius batteries are the 12V battery and the high voltage traction battery. Which of those two were replaced, two years ago?
     
  11. Jedi_Chic

    Jedi_Chic New Member

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    Thanks, Patrick! The spark plugs were replaced at approximately 200K (only 55,000 miles ago). The 12V battery, I believe, was replaced at 204K (it is the little boat battery in the back that runs the dome lights, etc.) It may have been more than 2 years ago. The other battery has not been replaced.
    Took it into the dealership. They did a general tune-up, replaced the spark plugs, and the ignition coil on cylinder #4 (as well as a recall on the steering intermediate extension shaft). Problem seems to be solved at the moment. Been driving it in various conditions for several days, and the shudder has not returned. So maybe it was just a bad spark plug and coil? Time will tell....
     
  12. 69shovlhed

    69shovlhed Surly tree hugger

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    probly just the #4 plug, but they did a coil too anyway. if you get that hard misfire again, don't be driving 80mph...