DEBUNKED ! Cold start , stop , restart = No knock

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by danlatu, Dec 30, 2017.

  1. danlatu

    danlatu Senior Member

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    It is 23 degree's outside with 19 degree's on the engine. Both engine's are cold and have not been started at all. I made these video's showing a 2010 and 2011 prius' being started and stopped WITHOUT proper warm-up to prove that engine knock does not exist when using an Oil Catch Can <-------------------Thread.

    I have read here that people are recommending to never start and stop a prius engine when it is cold or the prius will knock/shake/vibrate. The reason these engine's are knocking is from the oil/water/fuel that is sitting at the bottom of the intake manifold. Upon start-up the oil/water/fuel is sucked into the combustion chamber creating higher than normal compression ratio's. It accumulates there because the pcv valve blows it into the intake plenum from crankcase pressure also known as blow-by.

    The control. Meaning = to test or verify (a scientific experiment) by a parallel experiment or other standard of comparison.

    Video A. The 2011 prius has had an oil catch can since 297k from rebuild with a thoroughly cleaned egr cooler, egr pipe, intake plenum, intake and exhaust valves. This engine now has 305k.

    IMG_0221.JPG


    Video B. The 2010 prius has had an oil catch can since 80k from zero rebuild, zero egr system or intake plenum cleaning. This engine now has 115k.

    IMG_0222.JPG



    Both cars run great. All other routine maintenance intervals have been completed.

    These videos are unlisted and can only be seen through these links above. Enjoy.
     
    #1 danlatu, Dec 30, 2017
    Last edited: Dec 30, 2017
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  2. Mendel Leisk

    Mendel Leisk Sand Pounder

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    The "theory" was you start up cold, shut down in a matter of seconds, then the car sits, say for a further 24 hours. Then you get the knock. This is is what happened with ours, just the once.
     
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  3. danlatu

    danlatu Senior Member

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    Has it done this with an oil catch can? Having the car sit for 24 hours would allow contents on top of the cylinders to leak pasts the rings and into the crankcase/oil pan with that amount of time. The oil catch can would have prevented this knock because the intake plenum is free of contaminant. The contamination (oil/water/fuel)is what causes that knock. I know that the 2010 prius has knock on a cold start shut off because my girlfriend has forgot something inside. Has come back to start the car with a knock while engine was not fully warmed up. I shrugged at it the first time and thought she was crazy until it happed again. This was 3 years ago and since the oil catch can has been in place. It has not knocked since.
     
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  4. Mendel Leisk

    Mendel Leisk Sand Pounder

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    No, this was the once, pre-can. Yeah I think one of the parameters was the goodly delay to second start. I'm afraid to experiment, lol. I'm pretty biblical about avoiding short start up and shut down. If you're game to try, it'd be good to see how that goes.
     
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  5. 91TB78

    91TB78 New Member

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    What catch can are you running?
     
  6. iskoos

    iskoos Active Member

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    I started believing in this oil catch can and I think I will buy and install one when I start doing the routine maintenances.
    My car is at 143k. I got it last month at 142k. It is clean and runs good but it did this cold-start knocking on me once for about 5-10 seconds (and another time for like a split second). I was surprised when it happened but then I realized it is a common issue with Gen 3 models.
    I asked the previous owner. He said it never done it to him. Well I still love this car. It is an awesome daily driver.
     
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  7. danlatu

    danlatu Senior Member

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    A ball jar with stainless steel cleaning pads on the 2010 and ruien catch can (i would prefer more baffling) found on amazon for the 2011. I would have to put another catch can in series to see how effective both are. I know it does not trap 100% of the contaminant because of the discolored hose going to the intake plenum. I know they both work and I'm sure there's a better one. But how much better is it? It is a work in progress. At least the cars are running well. I don't like replacing head gaskets.
     
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  8. danlatu

    danlatu Senior Member

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    It never did this to him? That is why he was so eager to sell it maybe? I find that fishy. When it first happened to us @75k ish, the first thing I thought was trade it in. At the time I did not have the time to look at it cause I was out of town and my girlfriend told me about it over the phone. I was not happy because we owed money on the car and It was out of warranty. I bought it because it is a toyota. I found the problem and installed the catch can and knew about priuschat but was not a member at the time. I wanted to push more miles and time on it to verify it was the fix for the problem. I have read a lot of threads pertaining to blown head gaskets here on the 3rd gen prius. That is why I did not post anything here before I was sure. It was then I bought the 2011 with a blown head gasket to take a look inside to see what all the fuss was about. The cylinders and valves were heavily coated with carbon, signs of oil being burned in the combustion chamber. I bought the car because it was cheap and would give me the opportunity to get to the bottom of this and post my findings. I have always known of oil catch cans from racing but never thought in a million years that a prius would ever need one.
     
    #8 danlatu, Dec 30, 2017
    Last edited: Dec 30, 2017
  9. bisco

    bisco cookie crumbler

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    the catch can may be the answer, not sure how toyota would have implemented it as a fix, or why they dropped a bundle on improved intake manifolds that didn't work.

    the only way to prove it is to do as mendel said, and for a long enough period of time to be scientific. it doesn't always happen, which is even more frustrating because it's hard to show the dealer. conditions have to be just right.
     
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  10. iskoos

    iskoos Active Member

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    Well, I can't really say much but he told me it didn't do it to him. If he is lying, then he is lying. He just didn't seem that kind of guy to me. A nice husband; a dad to two kids. If he had said "Yes he experienced it", nothing was going to change anyways. I bought the car as-is.
    When you are buying a used car, there is always a risk. I looked for one accident-free (no body repair and paint job). You can't expect everything to be top notch.
    We will see how it goes with the car. So far, it has been running great (except the knocking I experienced). The car has been serviced at the Toyota dealer during the previous ownership. I got the service records and checking what has been done to the car in the past few years.
    Then I will devise a plan and start doing certain maintenances (like IM, EGR, PCV cleaning, Spark plug etc...)
    I have a spare car; that would take the pressure off me when doing maintenance...
     
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  11. iskoos

    iskoos Active Member

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    Correct. I read the entire 46+ page Knocking issue thread and found out that this can happen to any Gen3 owner (probably less the ones that use catch can and doing routine maintenance) at any time. It doesn't have to be cold, or hot,, or warm-up cycle interrupted, or anything. In that thread, there are many different scenarios where people experienced this issue.
    I wish Toyota would just install a similar device that would catch oil instead of spending money on that useless IM upgrade.
    I am pretty sure that they damn well know what the issue is. They just couldn't find a easy and economic route to get out of it. Instead they elected to ride it out. Now with the Gen4 is out, I am sure they feel more comfortable and let the time cure the wounds this embarrassing issue caused to company.
    But there are still a lot of Gen3 Prius out there and it will take many more years for this model to be completely out of the market.
     
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  12. bisco

    bisco cookie crumbler

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    i had it happen once in summer, after driving for awhile and pulling off of a 40mph road into a parking lot. i don't know if it was the same thing, but my father even asked me what all the racket was. shut it down, went shopping, got back in and it was gone, and never happened again.
     
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  13. danlatu

    danlatu Senior Member

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    I was at the stealership and asked to talk with a hybrid tech or master mechanic and they just laughed at me:) in regards to the start up knock and catch can. I don't think they want a fix. They know it will run great just past warranty so they can make money fixing the car. It is funny that other car manufacturer's are including catch cans as a stock item in the cars now. Some people are just late to the show I guess. It is also bad for business when things don't break. I read an article on jalopnik regarding Toyota struggling to catch up with the electric car tech. Maybe toyota has it's efforts in making 100% electric and has stopped research in combustion technology.
     
  14. bisco

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    i wonder if there are any reports on the gen 4 engine yet, it will be interesting to watch.
     
  15. ChapmanF

    ChapmanF Senior Member

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    That has a scientific sound, and got me started thinking about just what steps would be needed to approach this in a scientific way.

    1. We would need to know, replicably, how to make the knocking happen in a stock Prius. It doesn't happen to everyone, even everyone who makes short trips in cold weather, so there's already work needed just to be able to say "do these things under these repeatable conditions, and you will observe this when the car is stock." That's the "control."
      • It's possible that, even under strictly stated conditions, the problem can only be made to happen some fraction of the time in a stock Prius, and that's ok; experiments can deal with probabilistic behavior. The control result would end up being given as, roughly, "do these things under these repeatable conditions, and you will observe this with probability p", where p is some fraction less than one.
      • There is no observing p directly: p itself is a parameter of the underlying behavior, that can only be estimated experimentally. If you create the stated conditions and get the knock m times in n starts, then m/n is an estimate of p, but if you repeat that whole trial several times, you'll end up with several such estimates of p. That's what has to happen in order to reckon the tightness of the estimate of p. So the final statement of the control result would look like "do these things under these repeatable conditions, and you will observe this with probability p, which (we have c% confidence) lies somewhere between pmin and pmax."
      • That was all just about the control.
    2. Once a good statement like that can be made about the control, evaluating the OCC is straightforward; it just needs the same kind of repeated trials to be done in the same stated conditions, enough times to come up with a new estimate pocc of the probability of seeing the same behavior with the OCC in place. There will also be some range of confidence around pocc.
    3. Once such experiments have produced estimates of p and pocc, then if pocc < p, that suggests the OCC has some benefit, and the strength of the suggestion depends on how far pocc falls outside of the range of expected variation for p. In particular, the higher and tighter the range for p in the control case can be shown to be, the easier it is to show a benefit of the OCC. Conversely, if the estimate of p in the control case came out either (a) quite low, or (b) loose enough that rare or no knocking could be an unsurprising outcome for a particular trial even in the control case, then even if knocking with the OCC turns out very rare or unobserved, it's harder to show that means much.

    All of that's good, straightforward work that could be done, and would be interesting to read here; from the threads I've seen so far, there's still a need for digging into it, starting right off with (1).

    -Chap
     
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  16. danlatu

    danlatu Senior Member

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    I could throw some oil into the intake manifold right under the throttle body to get the prius to cold start knock. But it is cold outside and I would hate to blow a motor and have to pull it in these wintery conditions. Some people may think the shake/knock is normal and will ignore this article until their car blows up. I just need some more people to post there results like you have stated with/without a catch can for cold start, stop, restart. It would really give this thread some strength. Only great things can happen if we all come together. Thanks Chap!
     
    #16 danlatu, Dec 30, 2017
    Last edited: Dec 30, 2017
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  17. ChapmanF

    ChapmanF Senior Member

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    I imagine if you can get a Prius without an OCC to knock by doing that, you could get one with an OCC to knock by doing the same thing. :) That's ok; we're not actually trying to explain the behavior of cars whose owners pour oil into their manifolds, or to improve the behavior of cars whose owners do that, if there are any.

    The real trick is to come up with a concise statement of actual operating conditions, encountered by people merely operating their cars, not opening them up and pouring stuff in weird places, under which we can say the knock will occur with some high-ish probability.

    After that, it's just a matter of showing that the proposed remedy lowers that probability, under those same actual operating conditions, and lowers it by "a lot" relative to the confidence intervals around the two probability estimates (which implies taking observations quantitatively enough to have those estimates and those intervals).

    That would really give the thread some strength.

    -Chap
     
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  18. CR94

    CR94 Senior Member

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    That test could include both oil-guzzlers and non-guzzlers, if I may introduce another variable.
     
  19. Bill Norton

    Bill Norton Senior Member

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    I'm new to this thread but ^this^ is definitely not toyota's path. If anything they are advertising against the future.
     
  20. avidskier1973

    avidskier1973 New Member

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    New to prius chat. This forum has been invaluable for me.I prchased a 2010 Prius (base) with 250K with a CEL on constant not blinking, the owner (friend) advised me that the check engine light was diagnosed by his mechanic and the mechanic suggested he change the plugs. Ran the codes with an OBDII scanner. P0301 and P0302 came up. Misfiring in cylinder one and two. Some research and everything pointed to EGR system needing to be cleaned. Low and behold the EGR pipe, cooler and intake were completely clogged. I could not believe how clogged. I was able to get the cooler relatively clean (able to see a healthy stream of water when blowing powerwasher through cooler) and pipe along with the intake. Oh, I did replace the plugs before this mammoth task of taking the EGR system apart.
    Plugged OBDII scanner back in and erased codes. Shortly after P0301 came up again. I assumed the system was still getting used to being clean and expelling any additional toxins that may have been in the system. Erased codes again. Fast fwd two weeks and no more CEL but the engine shutter comes back periodically. I like your explanation that in theory keeping the oil out of the intake may make the shutter/knock go away and it's a relatively inexpensive fix. Any other wisdom out there anyone want to bestow?
     
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