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Rattling/vibrating at low throttle

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by mattcav30, Apr 25, 2017.

  1. mattcav30

    mattcav30 New Member

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    I have a 2010 Prius III that I bought new in November 2009. It has about 140k miles on the clock and I get ~42 mpg (per the display, not hand-calculated) in mixed highway and stop-and-go driving. I don't know about any oil consumption (I didn't realize that was an issue to look out for until I started poking around on here - whoops!).

    In the last couple of months, the engine has started rattling, sometimes causing the whole car to shake. It only does this at certain times though. Specifically, when I back off of the throttle and get close to the point where the engine shuts off and it runs on the battery. For example, if I am on the throttle fairly heavily going up a hill on the highway, everything will be fine, but as soon as I crest the hill and start to go down the hill, I'll let up on the throttle most of the way (though not enough for the engine to shut off), and the vibrating will start. It has nothing to do with speed, as I can replicate it at virtually any speed, and as soon as I back off the throttle entirely, the vibrating stops, regardless of speed. Similarly, if I am accelerating, no matter how quickly or gently, it runs fine. So it doesn't seem to have anything do with the engine running at a certain RPM - it is only when I am backing off the throttle.

    Additionally, if I am in traffic and the battery runs down low enough for the engine to have to kick on (when the battery indicator shows only two bars left), as soon as I start to accelerate gently, it starts making a loud rattling noise and the whole car starts shaking fairly violently (louder and more violently than with the other issue I described above). If I accelerate quicker (which I can't always do in stop-and-go traffic) or if I back off the throttle entirely, the rattling and shaking stops.

    Neither of these issues have lit up the CEL.

    In the last month or so, I have changed the spark plugs, cleaned the EGR pipe, cleaned the throttle body, changed the transmission fluid, changed the engine coolant, changed the inverter coolant, and changed the air filter (thanks @NutzAboutBolts for those!). A couple of weeks ago, I had the EGR valve changed at the dealership under the TSB. It initially seemed to be running a bit smoother after all of that, but within the last week, it has been back to its vibrating self. I took it back to the dealership for them to take a look at it, but they didn't come up with much other than wanting me to pay them $450 to take apart the intake manifold so they could poke around in there. The write-up said "possible EGR port inside intake manifold clogged; other possible causes could be camshaft gear noise or engine coupler between engine and transmission." I'm not inclined to pay them that much to just start poking around unless it's absolutely necessary. On the other hand, I wouldn't be excited if the engine dropped out of the bottom of the car because I didn't get it taken care of somehow.

    Thoughts?
     
  2. Former Member 68813

    Former Member 68813 Senior Member

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    IMHO, cleaning EGR pipe and valve may not be enough. You need to clean intake and maybe even EGR cooler.
     
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  3. Raytheeagle

    Raytheeagle Senior Member

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    Welcome to Prius Chat (y).

    +1.

    Sounds like you are the DIY type. The intake manifold is a 1.5 hour job. What did you see when you cleaned the egr pipe?

    How much oil is the car consuming and disna light on the dash let you know the level got low?

    Keep us posted
     
  4. mattcav30

    mattcav30 New Member

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    Thanks for the welcome. To say I'm a DIY-type might be overstating it a bit. More like brave-and-cheap-enough-to-attempt-a-DIY-fix-if-there's-a-great-YouTube-video-about-it-type (again, thanks @NutzAboutBolts).

    When I cleaned the EGR pipe, it was probably about 25-50% clogged.

    I think you misunderstood my comment earlier about oil consumption - I don't know how much, if any, it is consuming, as I didn't realize that was something to look out for until the last couple weeks when I started poking around on this forum. I just got the oil changed less than 1,000 miles ago, and the level seems fine now, but that may change after another 5,000 miles. I'll definitely be keeping an eye on it.

    No lights on the dash - I recall ever having a CEL on the car in its life.

    Do you know of any good tutorials on the intake manifold job? Or the EGR cooler job that @friendly_jacek mentioned above? Is the Haynes manual any good?
     
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  5. Raytheeagle

    Raytheeagle Senior Member

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    If you can wait until Sunday I'll have both of them ready:). @m.wynn and I will give it our best effort anyway as Saturday is when there is an Upstate NY meetup;).

    I have done both myself. They are not hard, but the egr cooler is best done when the windshield wiper cowling is removed. It is also a bit fiddly:(.

    I'll try to give you a good tutorial (y).
     
  6. mattcav30

    mattcav30 New Member

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    That would be fantastic. Thanks!
     
  7. m.wynn

    m.wynn Senior Member

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    It may be not suitable for small children, but we will have some sort of documentation detailing an entire EGR circuit cleaning. The spanners will be flying in the WynnStar (Star is my wife's name) team garage Saturday morning.

    mattcav30, did Toyota really give you an EGR valve with no CEL and P0401?.. One less part of the circuit for you to have to clean yourself, anyway. It's an odd thing they've done with that TSB, throwing a part at a code in what amounts to nothing but a stereotypical "parts changer" move, leaving the actual problem completely unattended to. Then waffling about a possible blockage in the intake manifold:rolleyes:... At least the factory trained techs have a hunch that your intake manifold, EGR circuit is packed full of black sludge:cool:. The cam gear and coupler nonsense is solid gold, though. This is how you build a multi-billion dollar corporate empire, peeps. Good intuition by you to not let them have at it. It seems the only way it will be done right is to DIY or explain to a good independent mechanic what needs to be done.

    In seriousness, it will be good to address your somewhat severe sounding symptoms in a timely manner. Part of the function of a cooled (or even non-cooled) EGR is to keep combustion chamber temps and rates down. It's not crazy to think these fully blocked circuits are contributing to the Gen 3 head gasket failure plague from detonation. I don't have fact to back this theory but I've personally upgraded Gen 3 EGR issues from performance nuisance to potential engine killer. And I've said several times now, Toyota needs to own this design fail.


     
  8. mattcav30

    mattcav30 New Member

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    Thanks, I'll look forward to whatever y'all come up with.

    Yes, they gave me the new EGR without a CEL. I was as surprised as you are. I didn't even really have to fight them for it; I just gave them the symptoms and they went ahead and did it. But yes, it doesn't look like replacing it actually did much of anything. Hopefully the manifold and EGR cooler cleaning will take care of it.
     
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  9. Raytheeagle

    Raytheeagle Senior Member

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  10. mattcav30

    mattcav30 New Member

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    That's fantastic, thanks! Let me ask you a few more questions.

    I thought I heard you say in the video that you had drained the coolant - is that necessary or can I just clamp off the hoses that attach to the throttle body? I just changed the coolant a month ago, so I'd rather not go through that again if I don't have to.

    Are there any special tricks to clean the intake manifold? Brakleen? Purple Power? Wire brush? Is there anything in there that I can break if I start poking around too hard?

    As for the EGR cooler, from what @m.wynn said in the other thread, it sounds like you just hose down the whole thing with Brakleen and wipe it down a bit. Anything more to it than that?

    I'm going to try to get at it this weekend, so we'll see how it goes!
     
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  11. Raytheeagle

    Raytheeagle Senior Member

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    No problem on follow up questions :).

    I've done this twice:
    • once with draining the coolant and plugging the hoses (lost about 1-2 ounces of coolant)
    • Once with draining the coolant and lost 4-5 ounces.
    If you do not drain the coolant, not only will the hoses be full of coolant, you will also have a full egr cooler of coolant.

    If only removing the throttle body, you can probably clamp them, but the manifold is difficult to get out, so dodging a couple of clamps may make removal more difficult.

    If you are talking about clamping the 4egr cooler hoses, it is already a constricted area, and you may not be able to successfully clamp the hoses and avoid a significant amount of coolant everywhere. If you just replaced the fluid last month, what I would do would be find some clean containers, drain it, set it aside, then put the same fluid back in. The coolant is composed of water, so extra moisture from the air will not hurt anything ;). Also, you would have to add coolant anyway after the amount lost, so why not try and save as much as you can, rather than end up with a lot of slick surfaces.

    We used wire brushes first to clean the intake manifold passages, then went with brake cleaner. For the egr cooler, I tried compressed air up to 120 psi and there were still deposits remaining:(. So I'll try carb cleaner next;). It should be the safest material to use, but other solvents will work.

    Good luck with your weekend project. If doing the egr cooler, a second or third pair of hands come in handy;).

    Keep us posted and take pics along the way(y).
     
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  12. Tanderson82

    Tanderson82 New Member

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    Did you end up doing this? Did it correct the problem? My car is doing the exact same thing. I am worried about potentially damaging something if I keep driving it this way. Thanks so much.
     
  13. mattcav30

    mattcav30 New Member

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    Yes, I was meaning to update this thread, but I kept forgetting about it. I did do the suggested steps - I took off and cleaned the manifold with brushes and brake cleaner, and then I took out the EGR cooler and hosed it down with brake cleaner until crud stopped coming out of it. While I had the manifold off, I also cleaned out the intake ports (not sure if that is the correct name) going from the manifold to the engine (2 clean ones and 2 dirty ones are pictured below), which were pretty disgusting. The manifold is easy to take off and put back on, but the EGR cooler was extremely difficult to get to. Access is very restricted, and my failure to follow someone's advice about stuffing a towel below it resulted in the loss of a socket into the depths of the engine bay. Also, when I turned the car back on for the first time after I put it back together, it was blowing a tremendous amount of dark smoke out of the exhaust, but that went away after I drove it on the highway for 10 miles or so.

    Having done all that, the good news is that I managed to get everything back together and running, but the bad news is that it helped the problem only marginally, at best. Gas mileage seems to have improved somewhat and the rattling is somewhat less intense, but it definitely did not eliminate the problem. So now I'm mostly back to square one.

    Anybody have any additional thoughts on what could be causing the problem?

    IM clean.jpg IM dirty.jpg
     
  14. Raytheeagle

    Raytheeagle Senior Member

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    Thanks for the update and sorry to hear about the loss of the socket:(.

    How many miles are on the Prius now? Have you resolved how much oil consumption (if any) you have? Can you quantify gas mileage now and has it only been 10 miles you have put on the car since the cleaning? Did you hold a light up to the cooler to confirm most passages were clear? Does it hesitate at all during any stage of throttle position?

    As always, keep us posted (y).
     
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  15. Hsieh2017

    Hsieh2017 Junior Member

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    I have actually a CT200h which is equipped with the same hybrid system as Prius gen.3.
    I have exactly the same problem as mattcav30 has. It took me almost 2 months to try to solve the problem.
    I check everything I could do(spark plug, egr pipe, egr valve,throttle body, loose clips,loose under cover...).
    Now I am planning to clean the intake manifold.
    However, I am quite shocked that after mattcav30 doing that much, the improvement is not very good.
    Did you try to unplug the egr valve connector to disable the function of the egr? This may tell us if the problem is really on the egr system or not.
     
  16. b100

    b100 Member

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    But.....did you cleaned the four small holes in de intake manifault? Those are the most important because when these are full of carbon your engine is going to shake.
    IMG_5987.JPG
     
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  17. Hsieh2017

    Hsieh2017 Junior Member

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    Let me share my experience of cleaning intake manifold for solving the same problem.
    I took down the intake manifold and the small egr gap passages inside the manifold did not clog seriously.
    Anyway, I cleaned them up. I used cleaner spary and brushes to clean the passages. Not easy to make sure the cleaning was complete, since the egr passages looked like a maze inside. I am sure the small holes and passages are unblocked but not sure they are complete smooth and distribute gas evenly.
    Finally, my CT still have small rattling noise under low throttle especially when backing off my throttle.
    I will try to remove egr valve and clean it. It is not a easy job since it is connected to egr cooler.
     
  18. Hsieh2017

    Hsieh2017 Junior Member

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    l unpluged the egr valve connector (deactivating the egr) and drove around today.
    Engine rattling remains. However, the situation when rattling shows seems a little bit different.I think the egr is not the problem or not the only problem.
     
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  19. davidvedenskii

    davidvedenskii Junior Member

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    @Hsieh2017 and @mattcav30 guys, I'm experiencing the same problem as you - engine is rattling/knocking/shaking at low RPM or when battery is low. Just paid $544 for cleaning IM, EGR Pipe, EGR Valve, changed spark plugs - didn't help the problem still exists. @Hsieh2017 after u plugged egr valve connector back in did the Check Engine light disappear by itself?
    @mattcav30 did u fix the rattle?

    I'm having 2010 Prius Two 169k.

    Thank you!!
     
  20. kc410

    kc410 Active Member

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