NEW!!! Service Bulletin for Engine Knocking at Startup T-SB 0012-10

Here is my follow-up.

Swapped the gasket and intake manifold about a month ago for ...054 part. As I stated on the previous page, the switch from the electric to ICE is now smooth as butter. Much better than before.

I recently left car in a garage for 10 days (heated, about 60F). it is quite humid here now, though. When I came back, had a rough start again. Did not last quite as long as before, only a few seconds, but sounded just as bad. So cannot blame the cold any more, although humidity may be the issue.

Nt sure what to do now. Should I go back to the dealer?

 

I'm curious what they changed in the intake, but probably I'll never know.

 

I would at least go if just to "get it on the Record" in case there is a fix later. I am reasonable sure there are no other options for a fix at this time. it sound like a fair amount of water is getting into the manifold, both my cars, that were just upgraded to the ....054 manifold from the ....052, The both had a lot of water in them. I believe this is what is causing the problem, but I am no expert.

 

My car has also started knocking on start up since the overnight temperatures in the Mid-Atlantic have hit the mid-40s (F) at night within the past week. I've also noticed it will knock if the car has sat for a couple of hours. Since it's a CPO car, it's heading to the dealer on Thursday and I'm driving my diesel pickup until then.

I'm mildly disappointed considering the car has just short of 19k miles on it, but this is what the warranty is for. I just hope the issue actually gets recognized and fixed.

 

I wouldn't really bother bringing it in, as it is incredibly hard to reproduce. I'm sure you noticed your knocking only occurs when the previous trip is very short, like a few seconds moving the car around the driveway. It's notoriously hard to recreate.

 

My 2010 did this, and now my 2012 did it as well.

I'll get the TSB taken care of on this one also, but my 2010 did it after they performed the TSB.

 

I solved the problem replacing the cylinder head gasket.
Gasket burnt and antifreeze began to fall into the cylinder.
Drove more than 3000 km of Problems no more.

 

Interestingly, my new 2013 Prius Plug-in has started doing this. Cold start each time in temps between 60-75F inside my garage. The 2010 Prius III had it and I had the TSB performed by a dealer and it still occured, though not as often. Seems odd they've had this problem for so long and it hasn't been rectified even though they've issued a number of TSB's.

 

My 2013 Prius v just scared me this morning by doing this. 28 degrees out when I started up, so it definitely got a cold soak. Would an engine block heater help with this issue, anyone? I would prefer to avoid this condition in the future.

 

Our 2011 did the rough start dance again yesterday. Think this was occurrence #4 since we've owned it.

 

If in fact the issue is caused by build up of condensation in the intake manifold, the heater wouldn't help, probably make it worse. The updated IM added ridges in the manifold to hold the condensation so it would get sucked in all at once during start up thus causing the misfiring. Apparently the redesign didn't help all that much in some case but seems to have fixed mine. I only had two occurrences early on.

Please notify your dealer and have them write it up.

 

I forgot to mention that I did move my car the night before.

The condensation theory is an interesting one. There must be some factor that causes greater condensation than is normal, otherwise this would occur far more frequently. Perhaps a partial warm-up of the engine creates more humidity in the intake manifold than it would otherwise see? I could see a mechanism whereby the air that escapes during compression causes condensation build-up that is normally dealt with by the heating of the intake and a return to the hot cylinder, except when the start-up process is interrupted and it collects...

I will report this to my dealer, but I plan on either making sure I completely warm up the engine each time I start the car or use EV mode for short moves. It doesn't sound like they have a solution for this, even with the new intakes. I would hope that they would have put the new intakes on the '13 models...

 

For those that have had the shakes, do you drive the car in Eco, Normal or Power?

 

ECO. It has subsided somewhat but will still occur enough to be annoying.

 

Being a sidelines mechanic I was thinking it might have something to do with the fact the IM is plastic. Possibly the heating/cooling differential of it being plastic instead of metal. With that said, our 11 rolla has the same plastic IM and it has never done this.

Mine did it early on and in the fall when we had high humidity days. The last episode was very odd though. I drove into town (about 20 miles so completely warmed up) and went into a store for about 20mins or so. When it started it went to town... so embarrassing as my family was wondering if the car was going to blow up.

 

ECO primarily.

 

I drive all modes, depending on situation, and change up frequently. EV is the least used, while normal driving is used most. I hit Power mode for getting on the freeway, passing or charging large hills. I hit Eco mode for cruising on the freeway or driving on the back roads near my house.

I've owned the car for two months and the humidity around the Seattle area has been pretty typical (above 60%) over those last two months. In contrast, the last couple of days, the low has been lower than normal for this time of year (around 50%).

I did wash my car yesterday, because it was sunny, so its possible that there was another source of humidity, but I would tend to discount that as highly unlikely. I think the interruption of the warm-up cycle on the engine has more to do with this. I may attempt to replicate the issue...

 

Bingo... many (in this thread even) have reported the episode after washing.

 

IIRC, the engine runs at a lower temperature in Eco. Maybe running in Normal will evaporate the condensation in the intake.

 

Never did the TSB on my 2011 with 45k miles so far. Problem did happened the first winter, two times.

So since then, every winter I use higher octane 89 -93 and one can of red HEET treatment a month(Nov, Dec, Jan, Feb.) east coast cold months.

Have not had the shakes again.
Car sits outside, no garage.

my2cents.