Serious Engine Knock less than 4000 miles brand new, done with Toyota

Discussion in 'Gen 3 Prius Main Forum' started by mwok86, Nov 12, 2010.

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  1. teeasal

    teeasal New Member

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  2. teeasal

    teeasal New Member

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    I read in an article on the newspaper auto section a while ago. It says that drivers should NOT have loyalty to any brand of gas, and should rotate filling up with various brands because different gas brands have different cleaning detergents so using all of them have less chance of leaving some deposits untouched.

    I always use Petrol Canada though, only because they have 2 cents off per litre with their City Master card.

    Maybe we should also report on what brand(s) of gas in Bob's poll?
     
  3. lolder

    lolder New Member

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    These cars don't get carbon buildups, especially with such low mileage. The current fuels, oils, lean burn and low blow-by have all but eliminated carbon for years. The Atkinson ICE also has high cylinder pressures and temperatures almost all the time so you don't have to "floor it" to blow it out. This is something else that is malfunctioning. I'd be surprised if it didn't leave a code but maybe not. Toyota should look into this.
     
  4. teeasal

    teeasal New Member

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    You sounded very positive and knowledgable about "these cars" but, where's the proof? Your "generally speaking" opinion isn't convincing enough, sir.

    I'm guessing that by "these cars" you mean similar designed new cars. But we are not talking about "these cars", we're specifically talking about the GenIII Prius, and the GenIII Prius is absolutely different in design from "these cars".

    Please explain if it's a malfunction then why it quiets down after people flooring it, and why it does not happen again untill 9k miles later?

    The Atkinson cycle's high pressure high temperature is exactly the cause of fuel dieseling if the pressure and temperature inside the cylinder goes marginally higher due to marginally higher carbon buildups.
     
  5. timo27

    timo27 Member

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    Interesting--they also mention Techron. When I had an old ('85 I think) Golf, the Techron or (I think it was called) BBK-40 were the only things that would keep it from getting carbon buildup to the point where the thing wouldn't run. Expensive, too, about $7/bottle at the time, and by the time the car was a few years old I needed to use it every thousand miles or so.

    The general behavior of that car was different than what the youtube here sounds like, though--in the Toyota case it lasts a few seconds and goes away--it does sound horrible, though, and I could understand peoples' angst. Could carbon deposits disappear that quickly? If it is carbon deposit, and it's showing up so early in the lifecycle of the car, I wonder what it will be like when we approach 100K or so. Hopefully it's something else; the fact that people seem to see it when they've just moved the car a bit, and later re-started it, suggests perhaps so. Let's keep our fingers crossed.

    Regarding the high-speed-European-country-of-your-choice tune-up, a mechanic once told me that with modern fuel injection systems, and ubiquitous detergent in gasoline, that would no longer work--that it was more suited to carbureted (sp?) engines. I do not know. I think cars, like people, probably benefit from a little exercise now and then...

    ~T
     
  6. Skoorbmax

    Skoorbmax Senior Member

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    I do floor this car every once in a while.

    I think no issues for 9k in my case were probably just luck, tbh. As far as I know nobody has been able to convincingly replicate this problem. Once they can, I definitely want to see if I can. At that point Toyota would actually have something to go on.
     
  7. fuzzy1

    fuzzy1 Senior Member

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    Where do you two get the idea that the Atkinson cycle ICE in the Prius has high pressures?

    Nearly everything here has pointed to our engines as having very ordinary ho-hum pressures.
     
  8. SW03ES

    SW03ES Senior Member

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    I agree with lolder, very unlikely that you would have any sort of significant carbon buildup in this engine at such low mileage.
     
  9. teeasal

    teeasal New Member

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    I didn't say "significant carbon buildup", I said "marginal carbon buildup". I DO NOT know for sure that the Prius atkinson cycle has higher pressure than other "normal" cars. I look at the symptoms and deduce that the Prius ICE was designed very close to the limit of fuel dieseling and that any marginal carbon buildup will trigger it, especially when temps are colder and the cylinders shrank in volumn overnight. I also deduced that this carbon buildup is easily blown away by flooring it because it's just MARGINAL.

    If you insists that I'm wrong, please list your reasons, not just throw out some expert statements like "these car don't have carbon buildup" without any reason/experience backup. I do have 15 (well, more like 5, the last 5 years of its live) years of carbon buildup experience with my ex-Honda Civic.

    I'm still waiting for someone, anyone to explain why, if this is a mechanical/electical/electronic defect, that it goes away after the drivers floor it, and it does not come back untill after 9k miles for one member, and some happened only after cold starting it and moved it a few feet, stopped and restart it again. All these symptoms point to MARGIANL carbon buildup.

    I don't have this happening to my Prius because, I REASONED, I routinely step on it in PWR mode thus blowing away any marginal carbon buildups. I invite members who experience this problem to "floor" it once in a while to see if this problem goes away, or it still comes back thus PROVING ME WRONG, not just speculating/declaring that I'm wrong with unsupported statements.

    Thank you very much.
     
  10. lolder

    lolder New Member

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    If it was carbon buildup, it wouldn't go away after a few seconds of running. Something is malfunctioning. Flooring it may temporarily clear the problem (maybe for thousands of miles). Yes, the Atkinsons are operated on the margins of knocking by design. They operate at large throttle plate opening settings all the time to run near the maximum torque available at the computer chosen RPM. Each combustion is optimized to be at the best efficiency which is near wide open throttle. There is little relationship between the throttle plate opening and the accelerator pedal position.There seem to be no complaints from older Prius's?? Carbon buildup came from low temperatures, idling, oil blow-by, leaded fuels, etc. None of these exist in the Atkinson hybrids. Something is not working correctly; a EGR valve, vapor purge, ignition timing software, injector operation, valve timing, etc. It could be dozens of things. This is a bad knock. It's not like a hydraulic lifter pumping up. It's not an advanced timing ping. It sounds like pistons hitting valves which would soon be catastrophic. I would hope that the system valve timing design precludes something like that. Has anybody checked for a trouble code soon after an event?
     
  11. qbee42

    qbee42 My other car is a boat

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    The Prius engine does not have unusually high compression, and given the way it operates, it is unlikely that carbon build-up is at the root of this problem.

    Tom
     
  12. bwilson4web

    bwilson4web BMW i3 and Model 3

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    If we can find a way to make it reoccur, I'll use my Auto Enginuity but it only reads out the emissions codes, not the full diagnostics. Still, it does record all of the emissions related data and I believe it also includes the spark advance.

    As for the knock, it is really hard to say. My first thought was 'rods' but that didn't make a lick of sense. I've not heard piston-valve impinging so I'm not sure. The only other knock I've heard in the past is low octane fuel in a high octane engine and to me, it seemed to have some of that characteristic.

    SPECULATION: ignition too far in advance induced knock?

    It would only have to happen for a few seconds and the knock sensor could retard the spark and make it go away.

    Bob Wilson
     
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  13. teeasal

    teeasal New Member

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    That's exactly what I think it is, but ignition too far in advance can be caused by dieseling due to too high compression ratio when the volumn in the combustion chamber becomes too small, maybe due to carbon build-up, or cold engine shrunk overnight, or both. It stops knocking in a few seconds is, maybe, due to carbon deposits being knocked loose, cylinder warms up and expand to normal volumn, and as you said, knock censor auto adjustment, or all of the above?

    I still can't believe that it's mechanical defect cause noway it will stop by itself in a few seconds.
     
  14. Skoorbmax

    Skoorbmax Senior Member

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    Must be fuel or air or timing or something like that. If it was a carbon deposit shook lose simply by idling, the idling, and throttle use normally would pre-shake it before it had time to get that bad to begin with.
     
  15. Fuel Miser

    Fuel Miser Junior Member

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    To Eliminate carbon as a possible problem I am currently running a tank with Redline SI-1 Fuel System Cleaner. If there are any deposits anywhere this stuff will get rid of it. I will then run a maintenance does and see if it returns. In the mean time I will continue to ask my dealer whats going on. I want an answer.
     
  16. teeasal

    teeasal New Member

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    Here's another thought, we know the Prius' Atkinson cycle is really a virtual Atkinson cycle by leaving the intake valve open longer so part of the air/fuel mix got pushed back into the intake manifold. Now if there's any minute loose carbon in the cylinders, what stops it from being pushed back into the intake manifold and possibly stay there amd accumulate. If the carbon build-up is occuring in the intake manifold and grow to a certain size over time, one eventful day it will be big enough to be sucked into the cylinder during the first crank of the ICE cold start and cause enough reduction of space leading to higher compression ratio and knocking occurs. Now this chunk of carbon is loose in the beginning so it's easily broken/burnt/blown away in a few seconds so the Prius ICE becomes normal again.

    Possible?
     
  17. Former Member 68813

    Former Member 68813 Senior Member

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    The talk about carbon deposits, dieseling and compression issue in Prius is just silly.

    I have a carburated engine in my boat that has those issues and I can assure you it is nothing like the knocking in Prius. The carbon deposits can indeed produce preignition and dieseling but on HOT engine after some high RPM runs.

    This doesn't fit with the cold engine Prius knocking. As the official TSB hinted (for 3 different engines I'm aware of), Toyota has mechanical issues with VTT/valvetrain and that is where the noise originates.
     
  18. teeasal

    teeasal New Member

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    Wow, calling someone SILLY who's sincere to discuss problems for other members is really friendly, Mr. Friendly!:mad:

    If your experience with a boat's carburated engine entitles you to be an expert in the Prius, please accept my kowtow, Master Friendly.:rolleyes:

    But tell me Master Friendly, if fuel dieseling can ONLY happen to HOT and high RPM engines, how on earth does a COLD Diesel engine ever start?

    You still haven't explain, as you expertly declared unilaterally, if this problem is mechanical in nature, WHY does it stop by itself after a few seconds of knocking?

    I'm NOT "declaring" expertise and saying this knocking problem of the Prius is definitely caused by carbon deposits. I'm just throwing out my thoughts and experiences as a suggestion.

    Prove me wrong and I'll be grateful. Throw unrelated experiences and expert-like statements WITHOUT PROOF at me and call me silly does NOTHING to me. It only prove your friendlyness and your expertise, or the lack there of.:D
     
  19. Former Member 68813

    Former Member 68813 Senior Member

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    The only comment I have is that I said "The talk about [...] is just silly." It clearly produced a rather big explosion here as I see. Yes, we do have a variety of people driving Prius.
     
  20. teeasal

    teeasal New Member

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    Since I'm the only one who's "talking about" it, and everbody else is pretty much against my idea, I took the liberty of interpreting your "silly" comment as pointing to me.

    This "big explosion" of mine is caused by post ignition (by your "silly" comment), not by pre-ignition high temp high pressure spontaneous combustion fuel dieseling though.:D
     
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