Engine Knocking/Shaking During Startup on 2012 Prius

Yes...I do....

 

I'm wondering if the problem has something to do with that. It's been said that the engine runs at a lower temperature in ECO mode and maybe it's not getting hot enough to burn off condensation. Just throwing that out there.

 

My wild guess (I'm not an expert on engines or the Atkinson cycle) but what I recall from a hybrid seminar given at my Toyota from some Toyota rep (who seemed pretty knowledgeable) in 06 and from random Google searches for atkinson cycle push mixture intake like below,

Today's Technician Classroom Manual: Automotive Engine Repair & Rebuilding - Chris Hadfield - Google Books

I recall the rep when showing his animation mentioning "guys" (as in air/fuel mixture) being pushed back out. Perhaps that air/fuel mix is detonating inside the intake manifold because it was at the right temperature, mixture and compression for it occur?

If so, that would make some sense as many of us know what diesel engines and dieseling sounds like...

 

The manual mentions the Camry having an Atkinson cycle engine. Are they having the same problem?

 

^^^
Don't know but Toyota hybrids have always been using Atkinson cycle engines, AFAIK, well before Gen 3 Prius.

But, Camry Hybrids don't share engines w/Priuses and Gen 3 Prius went to a totally different engine from Gen 2. I doubt the intake manifold is the same. Gen 3 Prius also added stuff like an exhaust gas heat recovery system. I believe that's used to help heat the intake air (someone correct me on this, if I'm wrong).

 

Yes. Camry's have the problem.

One example from Edmunds.

Toyota Camry Hybrid Rattles, Bumps, & Squeaks

The Camry folks call it the "Welcome Shake".

 

I have no idea if running in the ECO mode has anything to contribute......I do think you are on the right track; the IM does not run at a temperature high enough to prevent this "Water/Puddle" from forming......the IM is constructed from a type of composite & (apparently) does not transfer/conduct engine heat well......anyone know if the Gen. II used a composite IM? ....

 

Looks like I have the same symptom.

My car was towed to Wappingers Toyota today after car experienced vibration/clunking noise from engine, which occurred immediately after engine turned on after being parked in the garage for 2 days.

 

Did you get a Check Engine Light (CEL)?

 

Yes, car threw CEL, but never pulled the code.

 

^^^
Hopefully the dealer can retrieve the code and tell you what it is. It'd be interesting to know the outcome.

Why did you have it towed? Did the clunking noise and symptoms not got away after a power off and restart or you didn't try?

 

I tried to restart, but was unable to. With check engine light on, I just didn't feel safe to keep trying. I have towing service through insurance company by the way.

 

Interesting that you were unable to... what do you mean by that? The car wouldn't go into READY mode when pushing on the brake w/power?

 

Yes, that's correct.

 

Hmmm, I wonder if that's something different.

 

Got a call from Toyota dealer. They are replacing intake manifold.

 

Does anyone know if replacing manifold is a permanent fix?

 

Yes, I know..........It's not

 

Why do they have to replace the manifold if it's not a permanent fix? Did anyone have to pay out of their own pocket? if so, how much did it cost?

 

We were told that they were on the fourth or fifth iteration of the IM. They are obviously trying to get a fix by trail and error. We are their Ginny pigs.