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Detonation/ rattling under load

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by steveshow, May 19, 2010.

  1. steveshow

    steveshow New Member

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    My wife has an 08 with a little over 50k miles. When under load (climbing a hill) with the AC on, the engine "rattles". This sounds like classic detonation to me. It stops when I turn off the AC or she lets off the gas. I have tried running several tanks of super unleaded with no improvement. I have searched here and checked a few things others have mentioned as well, such as a loose hood prop rod with no success. The car just started doing this around 3-4k miles ago. Last week I changed the spark plugs, even though they are way under the mileage where I should change them. The plugs looked normal, a light tan color, with no unusual deposits or anything out of the ordinary. . Last night I checked and the engine coolant was a little low, so I topped it off. This had no effect as this afternnon on the way home I heard the same clatter when climbing a long hill. All this started back in march when the outside temps were still in the mid 80's... I wonder if it is possible that the pistons already have carbon at this low of mileage (?)
     
  2. jyoungprius

    jyoungprius Member

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    I hope someone can help you out with this, as I have had the same problem with my '09 Prius for a few months now. It only has less than 26,000 miles.
     
  3. derkraut

    derkraut Member

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    What you guys are describing is NOT normal. Since your vehicles are under warranty, take them to the dealer and have them diagnose the problem.


    Whoops! Guess the '08 is out of warranty. But I'd have the dealer drive it and check it out.
     
  4. jyoungprius

    jyoungprius Member

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    I had a local dealer's service dept. chech my car with "no problem found"...thinking I should get a second opinion
     
  5. northwichita

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    I wonder if the valves need adjustment.
    Edit------
    Sound is the main trigger for inspection of the valves from my recall.

    I've heard the valves rattle in my car a few times in very cold temperatures, when I accelerated before the engine had warmed up, and I backed off of course. The engine was fairly cold, the condition didn't last when the engine warmed up.

    175k on mine, and I've never looked at the valve train.
     
  6. edthefox5

    edthefox5 Senior Member

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    Have you figured it out yet? Running some higher octane gas through it without stopping the pinging is disturbing.

    I might have an idea but first I need to know what is your oil change schedule like? How often and what kind of oil your using please?
     
  7. V8Cobrakid

    V8Cobrakid Green Handyman

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    this may be a far fetch... but what about ignition coils? i had one fail yet experienced similar effects up to about 5,000 miles before the change. it was only a "problem" when the coil actually gave up and one cylinder was no longer firing.
     
  8. edthefox5

    edthefox5 Senior Member

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    I like that V8. That makes very good sense 'cause whatever it is is peventing the knock sensor activation from pulling back timing.
    If he is indeeed hearing pinging its in a world of hurt. Its way out of ecm control.

    I go with V8 and it has a mortal wound.
     
  9. Stephenblow200

    Stephenblow200 New Member

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    Dear Northwitchita,Me again.The same thing that you are experiencing seems to be what I am too.Although,I have never received a recall for this problem.Also mine never did have the hill problem only when the energy monitor read one bar purple did it struggle going down the road(up hill etc.)!I really apreciate your input in the last two to you so.Can you tell me how to force idle is there a switch or something?Also my engine has 117K and I may replace the spark plugs and have the coolant flushed because I talked with my mechanic and he says that this car has like a fuel filter/coolant type of device and that it is normal for people to have this cleaned or replaced in time because the engine will run a little better(like new plugs for the older cars,new filter etc.)somewhat.Also,I think that your problem is normal but I would get it checked if you have recall on it.Please tell me how you fare,so I might check this against mine.Thank you.I will watch for your post.Steve Blow.
     
  10. northwichita

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    Yes, I had brief detonation under load with a 'cold' engine, I just avoid that situation, I just take it easy the first couple blocks.
    There are a lot of good threads covering some of your other questions , searching this forum will give you better information than I can . Buying a repair manual also helps, though most of the information is found on the net if you look long enough. I did ask about forced idle in this thread and got some good answers .
    http://priuschat.com/forums/gen-ii-prius-technical-discussion/81611-safe-rev-in-inspection-mode.html
    I would pass on the fuel filter replacement, that is not a regular serviced item (its part of the fuel pump in the tank).