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    fuel_miser New Member

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    I've experienced the cold start engine knocking on my 2010 Prius. A Google search displayed a lot of people reporting the same problem. Does anyone know if Toyota's engineers are actively looking into this problem in regards to the Gen III Prius model? Has this issue been acknowledge by Toyota?
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    32kcolors Senior Member

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    They're aware of it but as with any companies they won't acknowledge until they come out with a solution. Many threads on this subject so do a search.
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    Skoorbmax Senior Member

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    I'm sure Toyota is aware of it but I haven't even seen so much as acknowledgement from them. It's impossible to know how many people have had this or any long term impact at this point because Toyota is deliberately staying mum.
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    Pri4Us Junior Member

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    Yours makes the 20th thread on this issue now... and after reading all of them, I recall a few PC posters who reported the dealership service representative they questioned admitted that they were personally aware of this anomaly. At this time, however, Toyota has not acknowledged this Rough Engine Start problem.

    Incidentally, at least one 2011 owner has also reported this issue.:(
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    Skoorbmax Senior Member

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    20 threads? Perhaps we need 30 for Toyota to speak to this. Or 40. I imagine we'll hit that count eventually.
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    cwerdna Senior Member

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    Yep.

    I'm not sure starting new threads will help. I know Doug Coleman and his colleagues posting as Prius Team and/or in podcasts have said something to the effect that it's best to contact the Toyota call center and get the complaint logged in their database. I suspect having enough of those will get the attention of the proper folks or bump up the priority.

    If a dealer service department logs nothing and blows off the problem, then there's a good chance that it's not get trickled further up. Even if it is, they may not have a good feel as to how common the problem is.

    Examples posts (even if these are OT):
    http://priuschat.com/forums/freds-h...er-heard-problem-toyota-line.html#post1140153
    http://priuschat.com/forums/gen-iii...ng-start-brake-noise-merged-7.html#post964400
    http://priuschat.com/forums/prius-h...app-ready-sync-fighter-ces-2.html#post1239586
    http://priuschat.com/forums/prius-h...ll-little-more-information-6.html#post1064441
    http://priuschat.com/forums/prius-h...ll-little-more-information-4.html#post1061546
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    The Electric Me Go Speed Go!

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    Has Toyota made any progress fixing the engine knocking on the 2010 Prius?

    I believe the answer is: Not that anyone is going to publicly admit to...

    I hear you knocking but you can't come in....
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    Chris2128 New Member

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    It could be that the oil used in these cars is way too thin, 0w-20 and/or your oil level might be too low. I do hear a very very slight and vibration when I start it cold but it's negligible compared to the older cars I have had
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    bisco cookie crumbler

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    how can you have a 2010 on order?:confused:
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    JimboPalmer Tsar of all the Rushers

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    As Mr. Coleman so frequently demonstrates, there is no hint that anything said of Priuschat ever reaches anyone at Toyota. Eventually after the Class Action Lawsuit is certified, Toyota in the US will become dimly aware there are unhappy owners and begin actively hiding this from the folks in Japan who might actually correct this.
    By the time Toyota in Japan is aware, the Gen IV Prius will be using a new ICE, so it will only be of academic interest to them.
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    Felt Active Member

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    I have not heard any knocking .... which could be a blessing of being a bit hard of hearing. But seriously, I assume some have the problem and some do not. It would be interesting to know if the problem is regional (confined to one area of the country)(the original poster of this thread lives in MD (close to sea-level)); fuel could be an issue?; octane? ethenol?; condensation in the fuel?; is the vehicle garaged? Oil was mentioned ....

    It is hard to imagine designing anything for a world-wide market with so many environmental, driving habits, elevations, quality of fuel and etc. variables ... I look at TV and see all the Toyota trucks hauling weaponry in Lybia ..... I wonder if they worry about a knock when starting? LOL
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    cwerdna Senior Member

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    Wow, I wouldn't go far as to say that. Some of the issues that have been discussed here have made it to him and his colleagues. In Detroit, Doug knew that some of us know how to inflate our tires. :D]

    I recall that Doug in http://whatdrives.us/podcast/episode-50-special-guest-doug-coleman discussed some difficulties w/some of the issues that arise. Some are fairly straightforward like the HID headlights. But for issues like the seat being uncomfortable, it's not as straightforward. IIRC, examples he gave were like, well, in what way? What if they make a change? Will that it make it uncomfortable for even more people or others? (This is from memory, someone else please correct me if I have this wrong.)

    I'd be curious if ken1784 or any other Japanese Priuschatters whether this occurs on JDM 3rd gen Priuses and whether they've gotten an answer from Toyota. Some folks in Japan might have better connections w/Toyota engineering and/or whoever handles these issues.
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    Skoorbmax Senior Member

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    Of course a huge problem diagnosing this is the incredible rarity with which it occurs. We've had it 2, maybe 3 times in 21k miles. It doesn't worry me, frankly (ok maybe it does a TINY but, but I mean really tiny. I'd more like to hear of resolution just for the heck of it). I am likely to purchase the car when the lease runs out. I still love the car regardless, and that was before gas prices took their recent jump.
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    cycledrum PSOCSOASP

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    If it happens, it bothers you and no satisfying response from dealer, call corporate at

    (800) 331-4331

    File a case. This is the channel where info is supposed to get to Japan. Engine knocking on startup is not quite so cool.

    Some of the videos I've seen are seriously not cool. It would piss me off in a new car. Any car actually.
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    Felt Active Member

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    No intent to be argumentative, but ..... isn't a "knock" associated with pre-ignition? Aren't there two cures ... raise the octane of the fuel, or retard the spark advance? And, I suppose carbon deposits in the combustion chamber?

    Because of the "rarety" of the occurrance ... I am suspicious of the fuel. From unintentional water in the tank? to criminal diluting the gas? Perhaps under-refining the fuel where it's octane is below the standard? I "think" the on-board computer should properly adjust the spark advance.

    Are there any reports of the ICE "knocking" in Europe? Asia? Latin America?
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    Pri4Us Junior Member

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    There have been numerous keywords used in related threads to describe the sound emanating from the engine compartment. "Knocking", "Clattering", "Rattling", "Bucking", "Clanking", "Banging", "Shaking", and "Violent Start-Up". I think most of the posters are characterizing the sound they heard, not its specific cause.


    Yes, there are a few. Two cabbies come to mind. One in the UK(GrumpyCabbie) and the other in Greece(socratesthecabdriver).
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    Skoorbmax Senior Member

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    Further it's almost universally caused after the vehicle during its last trip was driven a short distance (like from driveway to garage) and did not reach operating temperature, was shut down for some hours, then restarted and during the restart the knocking sound. Even then, it's rare.

    Nobody has yet identified a way to recreate this on demand every time, at least not on these forums.
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    Pri4Us Junior Member

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    Agreed! I'm convinced its cause is related to an interrupted ICE warm-up cycle coupled with the ICE restart after a yet undefined time period(which Toyota terms a 'cold soak').

    I don't think it's particularly 'rare'. I've logged 173 owners on PriusChat alone who have reported this issue. These PriusChat forum members represent a tiny subset of the total number of Gen III Prii sold worldwide but constitute a rather large percentage among Gen III PriusChatters. If one extrapolates this same rate of occurrence among the total number of Prii out there, the number of owners experiencing this phenomena has to range in the thousands... perhaps even tens of thousands.

    Actually, we appear to have one PCer who claimed to be able to reproduce this anomaly at will(hsiaolc). Others have had multiple occurrences of this problem when they inadvertently repeated the conditions you described above.
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    Skoorbmax Senior Member

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    "will(hsiaolc). "

    What did he do? The conditions I had this twice I applied one time and could not reproduce...
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    paprius4030 My first Prius

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    I happened to me again this am. This is the 2nd occurance in 47kmi. I just moved the car into the garage to put it away for the night and it wouldn't go into EV mode so the ICE started up. I let it run for mabe 2 or 3 mins. so this wouldn't happen in the am, but it did anyway. I was surprised it happened so I guess you have to let the ICE run quite a few mins. before turning it off.

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