Engine behaving strangely and popping hoses off intake manifold

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by anonymous, Jan 13, 2019.

  1. anonymous

    anonymous Member

    Joined:
    May 18, 2015
    142
    84
    0
    Location:
    California/Nevada
    Vehicle:
    2011 Prius
    Model:
    II
    So a couple weeks ago during a trip I noticed the engine behaving strangely: reving up and down repeatedly, reving up while slowing down to a stop as if it was engine braking, and running constant once stopped, when it's not supposed to.

    On the way home going uphill I heard a pop sound.

    Going down hill using engine brake, I heard an unusual whoosh sound while engine braking.

    After that, using the engine again, it was performing much worse, until `CHECK HYBRID SYSTEM` came on and forced me to pull over (near home). Error codes were P3190, P0171, P0101, P3190, P3190

    After restarting it was able to continue but ran very badly and shut down again after stopping at the gate.

    Turns out the PCV hose popped off the intake manifold, causing a massive intake leak. That's what the whoosh sound was from.

    IMG_2896.jpg

    I had a look in the tube and at the time thought it had a lot of build up in it but didn't bother with it.

    IMG_2898.jpg

    So I attached it securely with a worm-gear clamp and thought that was the issue fixed.

    IMG_2899.jpg

    Last weekend, we did the same trip, and noticed the engine behaving strangely again! When I parked and the engine continued running, I had a look under the hood but heard no intake leak. There were no pending error codes.

    Nothing happened until we got home, and nothing happened for most of a week while my father went to work with it, until yesterday; it failed again right when he entered the lot (and he creeped into the parking garage). So he took a rental and next day I went with him to fix it.

    This time the EVAP hose popped off the pressure switch thing. Error codes were P3190, P3190, P3190, P3191

    IMG_3127.jpg

    I put it back on; didn't have any clamps but was going to add a hose clamp at home.

    It appeared that somehow the intake manifold was having a positive pressure, enough to blow hoses off. My hypothesis was that the engine brake caused a positive pressure in the intake manifold… and based on my assumption that the PCV hose had a lot of build up, the PCV valve must be clogged, and was not letting excess pressure through (I thought PCV valves let pressure both ways at the time). And we never cleaned or changed the PCV valve with 212k miles. So I thought we should get a new PCV valve, and also should clean the intake manifold which I thought would certainly be very dirty with that disgusting EGR piping into it.

    After a while of city driving, during and after getting off a freeway, the strange behavior happened again, then POP (during acceleration from stop), followed by the smell of sulfur dioxide (smells like kitchen match burning). So I stopped at a parking lot and had a look with a camera; that hose popped off again! I was able to reach under the air box and plug it back in without disassembling stuff again.

    This invalidated my hypothesis that it was the engine brake, as little or no engine braking was used. (It could have done it a little during regen but the battery wasn't full so I don't think it did)

    When going home (which involves going over a hill) I tested how the hose might be popping off: I powered hard up hill and then used engine brake excessively going down hill. Looked (felt) the hose; IT DIDN'T MOVE A BIT!

    I took out the intake manifold (which was surprisingly quick and simple) to clean it and replace the PCV.

    I realized that what I thought was build-up in the tube was actually the shape of the tube itself!! facepalm copy.png
    IMG_3158.JPG
    (also at some point before I realized that the PCV valve only lets flow in one direction so it wouldn't backflow anyway; or at least I couldn't blow in the opposite direction… I do not know, does it let though with enough pressure?)

    The PCV valve… was perfectly fine. It had no build up, just some discoloration; and it sounded just like the new one when shaking it. (and pressing the spring felt fine too) so I cleaned it with the carb cleaner (wasn't much to clean) and put it back; left the new one to return. What's with people cleaning or changing their PCV valves after ~30k miles?! When ours has 212k and is still perfectly clean! I do not know, maybe it has less than that, but I'm pretty sure it has a lot more than 30k...

    Cleaned the intake manifold… There wasn't much to clean. But I found out how the EGR enters the manifold; I thought it just goes into the major channels and probably gunk them up, but actually it has its own sub-manifold with little holes into each channel of the actual manifold. So the EGR doesn't actually muck up your intake, it only mucks up itself. That was interesting.

    IMG_3167.jpg

    So I didn't achieve much by removing the manifold besides putting worm gear hose clamps on the PCV side of the hose. I put hose clamps on all the other hose connections, on the EVAP line.

    IMG_3168.jpg IMG_3181.jpg IMG_3178.jpg IMG_3180.jpg

    So. Presently the engine continues to behave strangely intermittently. To recap, that is, it speeds up and down… on the freeway, on city streets, at low speed (especially noticeable then)… when slowing down it may stay running at high speed until when stopped; when stopped it becomes constant, staying running when it shouldn't be (battery full and not warming up). And it does that even in stealth with battery full, even coasting downhill, even when switching to NEUTRAL! But yeah when stopped (even in neutral) it runs constant, but when moving it ramps up and down… This strange, like, engine retardedness, is sort-of intermittent, like it may be like that then not be like that then be like that… but hmm, it looks like it begins happening after a while of driving; never happened soon after cold start.

    I orginally thought it was behaving strangely because of the hose that popped off, but apparently it's the other way around. First the engine behaves strangely. During which presumably it somehow pressurizes the intake manifold. Causing the hoses to pop off. Now that the hoses are securely fastened, theoretically they will not pop off, and the car will not die, but the engine will continue to behave strangely, which I do not yet know why. (but yea hopefully it at least wont die again)

    Soo... any ideas? No error codes or pending codes are logged when this happens. We've thought about an intermittently malfunctioning sensor. Or, during writing this post, realizing it only happens in the later part of trips, maybe it has something to do with heat??
     

    Attached Files:

    #1 anonymous, Jan 13, 2019
    Last edited: Jan 13, 2019
    Mendel Leisk likes this.
  2. anonymous

    anonymous Member

    Joined:
    May 18, 2015
    142
    84
    0
    Location:
    California/Nevada
    Vehicle:
    2011 Prius
    Model:
    II
    oh btw; we've had similar issues before. First time something like this happened was a long time ago when i noticed the engine revving when slowing down on an exit: Engine runs when braking | PriusChat

    Second time was when gas cap was apparently loose Engine behaving strangely and check engine light on | PriusChat (or was it really? cause that was a little odd… and then when gas cap finally failed to seal it did not have this issue IIRC P0171 P0441 P0455 | System too lean AND Evap leak detected | PriusChat)

    Certainly never had hoses popping off the intake manifold before, though.
     
  3. iskoos

    iskoos Active Member

    Joined:
    Dec 24, 2017
    303
    201
    0
    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    III
    Thanks for documenting everything with pictures and timeline.
    Engine reving up and down sounds like a vacuum leak to me. But you are saying excessive pressure causing those hoses to pop off and this doesn't go along with the vacuum leak theory.

    I do agree with you on your theory of positive pressure causing those hoses to come off. However, I am not sure if it is a good idea to clamp those hoses in your case since you didn't find what's causing the issue. Clamping those hoses tightly may not be the best thing to do at this time.

    One theory I am thinking is that you maybe getting too much blowby causing this extreme positive pressure that the pcv system cannot handle. One thing you may try (in the meanwhile) would be a vented oil catch can. It is easy to install. This would obviously introduce a vacuum leak but since you already have an excessive pressure, it may not affect you. However this is not a fix to your case, it is just a temporary solution. You need to find the reason for the excessive pressure. It may be a good idea to perform a leak down test and see how your piston rings are doing.

    Have you searched this forum or google for "excessive positive crankcase pressure/excessive blowby" or similar?
     
  4. tankyuong

    tankyuong Senior Member

    Joined:
    Nov 9, 2012
    1,356
    593
    0
    Location:
    Central MO
    Vehicle:
    2012 Prius c
    Model:
    II
    Egr cooler probably is clogged
     
    TomB985 and Raytheeagle like this.
  5. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    5,288
    3,721
    1
    Location:
    Wilkes Land
    Vehicle:
    2012 Prius
    Model:
    Four
    Clogged to the point where there's no escape and hose came loose with pressure backed up. Anyone seen bill norton, just wondering.
     
    Raytheeagle likes this.
  6. iskoos

    iskoos Active Member

    Joined:
    Dec 24, 2017
    303
    201
    0
    Location:
    Orlando, FL
    Vehicle:
    2010 Prius
    Model:
    III
    EGR cooler being blocked cannot explain the excessive pressure in the crankcase. The EGR system diverts portion of the exhaust gasses back in to the intake. If it is blocked, then those gasses will have to exit through the way they originally designed to: That is the exhaust system and tailpipe.
    Plus the EGR system has a valve to regulate the exhaust gasses into the intake and sometimes (during warmup and idling) that valve is totally closed and the engine runs just fine.

    So although it presents its own problems, I do not think what's happening here is due to the clogged EGR cooler.

    But given that the OP is capable of turning a wrench, he wouldn't lose much to dig into that area and make sure everything is clean.
    It is an extensive work though. I have just done it a few weeks ago. I don't want to do it again.
     
    Mendel Leisk and GrGramps like this.
  7. padroo

    padroo Senior Member

    Joined:
    Jan 11, 2008
    2,763
    2,243
    13
    Location:
    Chesterton, Indiana Another third world country.
    Vehicle:
    2016 Prius
    Model:
    Four
    The PCV valve acts like a cheap check valve and only works in one way. Sounds like the excess pressure is more than the PCV valve is able to vent. I'm thinking blown head gasket. Put a pressure gauge on the dipstick tube, just curious.
     
    Robert Holt likes this.
  8. Mendel Leisk

    Mendel Leisk Sand Pounder

    Joined:
    Oct 17, 2010
    44,650
    31,972
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Intake valves not sealing??
     
  9. Robert Holt

    Robert Holt Senior Member

    Joined:
    Aug 3, 2013
    1,312
    874
    0
    Vehicle:
    2012 Prius
    Model:
    Three
    Could I also suggest the over pressurization of the crankcase could be simply due to very worn , or possibly stuck, piston rings? In either case the blow-by exhaust gasses that go down past the worn/stuck rings pressurize the crankcase to be an abnormally high pressure, particularly under high load situations . If I am correct, the problem with carefully reconnecting those hoses to be tighter would be that at some point the excess crankcase pressure can start to push oil past the engine seals, most likely the seals at either end of the crankshaft. I like the idea of a pressure gauge on the oil dipstick tube for diagnostic purposes , although I have never tried that, but you might have assess a normally running Gen 3 in exactly the same way at the same rpm and load in order to see if your engine has a crankcase over pressurization problem.
     
  10. padroo

    padroo Senior Member

    Joined:
    Jan 11, 2008
    2,763
    2,243
    13
    Location:
    Chesterton, Indiana Another third world country.
    Vehicle:
    2016 Prius
    Model:
    Four
    A cylinder leak down test will show all the faults.
     
    scona likes this.
  11. Mendel Leisk

    Mendel Leisk Sand Pounder

    Joined:
    Oct 17, 2010
    44,650
    31,972
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    This is a really interesting mystery btw.
     
    anonymous likes this.
  12. anonymous

    anonymous Member

    Joined:
    May 18, 2015
    142
    84
    0
    Location:
    California/Nevada
    Vehicle:
    2011 Prius
    Model:
    II
    You are right, I should have left an accessible connection unfastened, maybe even slightly lubricated. I think it has blown something deeper in the EVAP system.

    Today since cold start the system was wonky. I checked for pending codes and found the familiar P0441 and P0455 (large leak in EVAP system), which we've had before due to a badly sealing gas cap (OEM is poorly designed; threads bottom out before gap for gasket is fully closed) with the same behavior. That makes sense; EVAP is connected to intake manifold so a leak in the EVAP means an intake leak and thus engine wonk.

    So I picked up a clamp at home depot and clamped the EVAP hose, and removed a hose clamp before it in case it pressurizes again. That stopped the engine wonk, though I thought I heard some fluctuation at higher speeds, but probably not.

    So now I think the past engine wonk which would happen before a hose pop was caused by the hose loosening and leaking a little before popping off completely, rather than the engine behaving wonky causing the hose to pop off. Which means there are no noticeable symptoms accompanying the original issue.


    The EGR cooler was recently just cleaned and is still functional. There is no engine rattle.

    The PCV valve is screwed directly into the engine block. If it was blocked the pressure would be contained within the engine block, before the hose. But the top of the crankcase is connected to the rubber intake pipe, so it wouldn't be possible for it to build up pressure because it would just backflow into the intake? Or does it go though a check valve? Also, the manifold side of the PCV hose is not blocked either.

    I just tested the flow from the dipstick tube with my fingers. I felt absolutely no flow, while the system is warming up at least.
    Edit: After reading this thread I tested for blow-by by removing the oil cap while the engine is running, and oh! There is a lot of blow from it, I guess similar to a hair dryer on medium like they had.
    Edit 2: Looks like that may be normal and not mean anything. I will consider using a pressure gauge on the dipstick. I have a water pressure gauge but may need some fittings to attach it.
    If I still can't find the issue then I may try a compression or leakdown test. I also considered getting Techstream to diagnose.
     
    #12 anonymous, Jan 14, 2019
    Last edited: Jan 14, 2019
    Robert Holt likes this.
  13. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    4,278
    4,626
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    Every time I've seen a crankcase pressure issue, there has been oil blowing out the dipstick. You're blowing hoses off, but nothing out of the dipstick? Seems odd to me...
     
  14. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,356
    4,302
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    An old pilot told me that seeing oil leaks was a good thing- it means you haven't run out of oil yet.

    I'm asking just because it hasn't been mentioned so far- does the engine have any/enough oil in it?
     
  15. padroo

    padroo Senior Member

    Joined:
    Jan 11, 2008
    2,763
    2,243
    13
    Location:
    Chesterton, Indiana Another third world country.
    Vehicle:
    2016 Prius
    Model:
    Four
    The reason I always recommend a cylinder leak down test over a compression test on a Prius is that it is hard to get a five second crank out of a Prius and you run the risk of running the HV battery down.

    The cylinder leak down test will also show you where the leak is coming from. You need the leak down gauge and an air compressor.
     
    Robert Holt likes this.
  16. Mendel Leisk

    Mendel Leisk Sand Pounder

    Joined:
    Oct 17, 2010
    44,650
    31,972
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    That's where a competent garage might come in handy.

    Every so often my mind turns to air compressors, I start looking things up, the $'s keep escalating, and at some point I give my head a shake, look at my situation, and it passes. But it comes back...
     
    anonymous likes this.
  17. Grit

    Grit Senior Member

    Joined:
    Aug 22, 2017
    5,288
    3,721
    1
    Location:
    Wilkes Land
    Vehicle:
    2012 Prius
    Model:
    Four
    Force charge to all bars before you begin mi amigo.
     
  18. padroo

    padroo Senior Member

    Joined:
    Jan 11, 2008
    2,763
    2,243
    13
    Location:
    Chesterton, Indiana Another third world country.
    Vehicle:
    2016 Prius
    Model:
    Four
    I have an air compressor for all occasions, big, middle and small. One big enough to do a leak down test can be bought for under $100.
    Not much excuse for not having one nowadays.

    http://www.harborfreight.com/air-tools/air-compressors/3-gal-13-hp-100-psi-oil-free-pancake-air-compressor-61615.html

    http://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore%2Cf%2CEAFeatured+Weight%2Cf%2CSale+Rank%2Cf&q=leak+down+tester
     
  19. EBATX

    EBATX New Member

    Joined:
    Dec 2, 2018
    3
    4
    0
    Location:
    Austin, TX
    Vehicle:
    2011 Prius
    Model:
    Two
    This sounds like an experience we had on our 2011 with similar codes. TSB-0041-15 seems to have fixed it. $400 at the dealer.
     
    SFO and anonymous like this.
  20. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    4,278
    4,626
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring

    A semi? known problem, just not important enough for a recall. So it's free if you're 'lucky enough' to have it happen under while under warranty, but shanked for 4 hundo if not. Gotta love those little issues that pop up.
     
Loading...