1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Loud, Rough Cold-Start= Exhaust Manifold Replacement. Why?

Discussion in 'Gen 3 Prius Technical Discussion' started by mtbjay, Oct 12, 2012.

  1. mtbjay

    mtbjay New Member

    Joined:
    May 24, 2011
    8
    2
    0
    Location:
    Portland
    Vehicle:
    2011 Prius
    Model:
    II
    Edit: It is the intake, not exhaust, manifold that is being replaced. (Makes more sense to me now!)


    My wife's 2011 Prius 4 is currently having the INTAKE manifold replaced under warranty after we complained of 3 rough cold starts. She explained the phenomena as a violent shuddering, very loud clanging and an engine that was struggling to start (or stay running). This problem would resolve itself after 10-15 seconds each time. Incidentally, the car had been parked outside each time in cool, but not cold, temps.

    I wondered if it was concurrent with me quickly backing out of the garage and powering down the car mid warm-up cycle (before the engine quit it's warm-up cycle). I theorized doing so might have caused the engine management system to stumble the next time the car was started. Apparently, my wife discovered similar complaints and the subsequent fix was to let the car complete it's warm-up cycle before powering down. The Service Writers at the dealership apparently had no knowledge of this.

    The initial inspection revealed no service codes and the Service Writers told us to not worry and to simply keep driving it. I complained that something was very wrong and explained that if the noise was indeed the same as in the video my wife found on-line (that she insisted was the same rough starting sound her engine was making) I was worried it could be the sound of an oil-starved engine. The Service Writer assured me this was not the issue because our Prius has a mechanical oil pump and when the engine turns over the oil is flowing. I said, please have the tech call me and explain what he think the issue could be then.

    An hour later "new information suddenly came to light, man" and they said they'd try replacing the intake manifold. Apparently some service bulletin led them to believe this could be a fix. We'll see, I guess. I was wondering how a faulty intake manifold could cause a very occasional rough start? I don't know enough about cars to say.

    Meanwhile, I'll be sure to test my theory on interupting the warm-up cycle anyway.
     
  2. jjPrius

    jjPrius Junior Member

    Joined:
    Feb 6, 2011
    68
    19
    0
    Location:
    Southern California
    Vehicle:
    2011 Prius
    Model:
    III
    The bulletin they are speaking of involves replacing the intake manifold (not exhaust manifold as they may have told you). What does seem interesting is that the revised manifold discussed in T-SB-0010-12 was used as a running change to the MY 2011 vehicles. Not sure why your 2012 would benefit from another of the same manifold.

    Let us know how it goes.

    Jeff
     
  3. mtbjay

    mtbjay New Member

    Joined:
    May 24, 2011
    8
    2
    0
    Location:
    Portland
    Vehicle:
    2011 Prius
    Model:
    II

    Okay, my mistake. The wife just confirmed it was indeed the "INTAKE MANIFOLD" being replaced, not the exhaust. Now it all makes sense to me, especially given the TSB sticky and this explanation in the replies:

    The dealerships have the TSB already, so if you bring the car in it should be fixed..., but for sure this fixes the issue, ive seen it first hand, the new manifold has numerous ridges in the part of the manifold where it connects to the egr pipe..., whereas the old one it completely straight..., the ridges act like a dam preventing the water that gets built up in the egr pipe from being sucked into the cylinders all at once (which is what happens in the morning on a cold startup), now it allows the water to atomize properly...






    Will edit post. Oh, and it is a 2011...
     
    jjPrius likes this.
  4. katiesdad7

    katiesdad7 Member

    Joined:
    Feb 18, 2011
    172
    25
    0
    Location:
    Stuart, FL
    Vehicle:
    2011 Prius
    Model:
    Three
    Is this covered even after the warranty expires since there is a TSB?
     
  5. jjPrius

    jjPrius Junior Member

    Joined:
    Feb 6, 2011
    68
    19
    0
    Location:
    Southern California
    Vehicle:
    2011 Prius
    Model:
    III
    It is only covered under the Powertrain warranty (60 mo. / 60k miles) OR it will be covered under the CA Emission warranty in certain states until 180 mo. / 150k miles.
     
  6. mtbjay

    mtbjay New Member

    Joined:
    May 24, 2011
    8
    2
    0
    Location:
    Portland
    Vehicle:
    2011 Prius
    Model:
    II
    Update: The INTAKE MANIFOLD was indeed replaced, under warranty, on our 2011 Prius 4. So far, no rough starts like the previous two that, according to my wife, rattled and shook the whole car. Unfortunately, I had to put up quite a stink at our local dealer to get them to try something. (And low-and-behold, a Toyota Service Bulletin suddenly appeared. Go figure..)

    I never tested my theory about interrupting the warm-up cycle, resulting in a rough subsequent start. If I do, and it stumbles, I will be sure to post it here.
     
    jjPrius likes this.
  7. JohnF.

    JohnF. New Member

    Joined:
    Nov 2, 2012
    2
    1
    0
    Vehicle:
    2012 Prius
    Model:
    N/A
    I am having the same issue with my 2012 Prius, it seems like if you start it and move it quickly and shut it back off before it warms up, the next time you start it, sounds like the engine is knocking, rattling, about to fall out. I am going to take my car in to the dealership as well. Mtbjay, I just don't understand, there should be no water in the intake manifold or in the EGR passages, who gave you that information ? Any water inside the motor will damage it unless it is flowing in the cooling system.
     
  8. WE0H

    WE0H Senior Member

    Joined:
    Mar 25, 2010
    3,247
    528
    0
    Location:
    Minnesota
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Sounds like you either got an older intake or the new design didn't cure the issue. Solution is to never let the ICE start up and you shut it down before it goes thru it's warm up cycle, which is only a minute or two.

    Mike
     
  9. Unlimited_MPG

    Unlimited_MPG Member

    Joined:
    Sep 20, 2007
    218
    24
    0
    Location:
    Federal Way, WA
    Vehicle:
    2011 Prius
    Model:
    Five
    I had the TSB for the manifold done on my 2011 Prius a while back. Just last month had the knocking noise come back. Although before the knocking would last 15 to 21 seconds, it now only goes for a very short 3 seconds.
     
  10. WE0H

    WE0H Senior Member

    Joined:
    Mar 25, 2010
    3,247
    528
    0
    Location:
    Minnesota
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    So mostly cured :)

    Mike
     
  11. Codyroo

    Codyroo Senior Member

    Joined:
    Oct 24, 2007
    1,826
    515
    6
    Location:
    Pleasanton, Ca
    Vehicle:
    2010 Prius
    Model:
    IV
    I've noticed that the 2 or 3 times it has happened to me was when I was trying to move my car from my driveway to the curb in front of my house (after washing the car). If the engine just fired up (< 3 - 5 seconds) and I shut it down, I would get the knocking event. Now, I just let it run for 15 seconds or so to avoid it.

    Dumb.
     
    WE0H likes this.
  12. Unlimited_MPG

    Unlimited_MPG Member

    Joined:
    Sep 20, 2007
    218
    24
    0
    Location:
    Federal Way, WA
    Vehicle:
    2011 Prius
    Model:
    Five
    Mine seems to always happen when I wash it also. Water / moisture is getting in somewhere and causing the knocking.
     
  13. WE0H

    WE0H Senior Member

    Joined:
    Mar 25, 2010
    3,247
    528
    0
    Location:
    Minnesota
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Maybe she's not happy 'cause you got her wet [​IMG]

    Mike
     
    Unlimited_MPG likes this.
  14. mtbjay

    mtbjay New Member

    Joined:
    May 24, 2011
    8
    2
    0
    Location:
    Portland
    Vehicle:
    2011 Prius
    Model:
    II
    Yup, my wife says it happened after I washed it (when I shut her down before the engine finished it's warm-up cycle and shut down on its own.) It's a defect for sure, and an annoying one at that. Too bad Toyota missed that.

    I did notice once, when I may have shut the engine down 10-20 seconds after the warm-up began (but before it shut off on it's own) that there was an brief stumble upon start-up (2-3 seconds, like others have reported). And that was shortly after the new intake manifold was installed. So, apparently, it's an issue not entirely solved by the redesigned intake manifold. But letting your car go through the start-up cycle before shutting it down when quickly moving it, seems to alleviate the issue.

    JOHN F., I found the explanation right here on this forum:

    (Author: KORE971 Date: 1/12/12)
    The dealerships have the TSB already, so if you bring the car in it should be fixed..., but for sure this fixes the issue, ive seen it first hand, the new manifold has numerous ridges in the part of the manifold where it connects to the egr pipe..., whereas the old one it completely straight..., the ridges act like a dam preventing the water that gets built up in the egr pipe from being sucked into the cylinders all at once (which is what happens in the morning on a cold startup), now it allows the water to atomize properly...











     
  15. ProphetsOfDoom

    Joined:
    Oct 28, 2012
    95
    93
    64
    Location:
    Virginia
    Vehicle:
    2012 Prius
    Model:
    Three
    Interesting… I experienced this same type of issue with my 2012 last weekend when I was installing my carbon fiber dash.
    I had the doors open for a long time (i.e. interior lights on) when I noticed the lights start to dim. I started the car to allow the alternator to charge the battery. I don't recall exactly but i just remember starting the car and hearing a loud “tapping like” noise coming from the engine compartment. The car shook too. It only lasted a few seconds and has not happened since. My Prius is only a month or so old :(

    I didn't associate it with the quick start up/shutdown... although I may have started the car and turned it off fast because the garage door was closed. Then opened the garage door and started it again, and that is when I heard/felt the noise.

    Should I be worried about this?
     
  16. WE0H

    WE0H Senior Member

    Joined:
    Mar 25, 2010
    3,247
    528
    0
    Location:
    Minnesota
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    It appears all of our cars will do this. Toyota might want to design a new intake or just give all of us a extended warranty to cover the gas motor (ICE) if it should fail later on. Now that we have identified how this issue happens, owners can eliminate the issue by letting the computer run the motor through it's warm up cycle before powering the car down.

    Mike
     
  17. xStatiCa

    xStatiCa New Member

    Joined:
    Aug 19, 2009
    4
    0
    0
    Location:
    FL
    Vehicle:
    2010 Prius
    Model:
    III
    My 2010 Prius just had this problem yesterday (bought it late 2009). It occurred when I moved the car from the driveway to the street. My wife started it up the next morning and it ran rough at start-up again. We took it in to Toyota and they are replacing the intake manifold.

    I just don't understand why we never experienced this before but we have now. What changed? Why now? I have moved it from the driveway to the street before without issues.

    It seems like the car engine turned on even though I was under 10mph moving it from the driveway to the street. I wonder if putting the car in EV mode would have kept the problem from occurring.
     
  18. Codyroo

    Codyroo Senior Member

    Joined:
    Oct 24, 2007
    1,826
    515
    6
    Location:
    Pleasanton, Ca
    Vehicle:
    2010 Prius
    Model:
    IV
    I'm assuming that this time the engine fired up and ran for just a few seconds, whereas before maybe it didn't fire up at all or if it did fire up, it ran longer (10 seconds or more).

    It won't go into EV if the engine is too cold, even if you keep the mph below 10 mph (you'll get a warning message if you press the EV button when the engine is too cold).

    If you have the opportunity (but I doubt you will get it) it would be great to have the tech power up the car (cold engine) until the engine runs and shut it down after 2 seconds. Then restart to see if you still get the knock (the advantage of having the tech do it is that is it already at the dealership and they can't say you imagined it.

    But, likely, you'll get your car and the engine will already be running and warming up (past the stage where you could shut it down and get a repeatable knock). The only other alternative would be to leave it there a few hours or overnight, and do the quick power up and shutdown on a cold engine.
     
  19. etobia

    etobia Member

    Joined:
    Sep 8, 2008
    116
    11
    0
    Location:
    NEW YORK STATE
    Vehicle:
    2010 Prius
    Model:
    III
    PLEASE.....I need to see the video your wife found online. My dealership is trying to get my Prius to rattle again before they dive into this major repair.
     
    1945steve likes this.
  20. WE0H

    WE0H Senior Member

    Joined:
    Mar 25, 2010
    3,247
    528
    0
    Location:
    Minnesota
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Here's one:


    Just search You Tube for Prius Knocking.

    Mike