What happens when the Prius charges the HV battery when the car is parked?

What sequence of events is initiated when Prius decides to charge the HV battery when the car is parked or otherwise at rest?

I am trying to resolve a problem where the engine begins to shake and knock when the charging process is initiated and immediately stops when the charging process stops.

I can confirm the cause and effect by monitoring the status display. The charging arrows show energy being directed from the ICE to the HV battery and the battery bars begin to rise above 2 bars. The knocking sound is very similar to a pre-ignition knocking sound except this starts and stops in concert with the HV charging.

Example:

Prius in Inspection Mode / Idling at about 1000rpm.

Calculated Load is 34% without charging (Engine sounds normal)

Calculated Load is 68% when charging (Engine shakes / knocking sound)

I'm hoping this information will provide clues to resolve the knocking problem on my 2010 (with over 300K miles) by understand the steps and interaction that occurs when the charging process is in play.

 

Thanks for the feedback... your help on this problem is very much appreciated.
This problem had been driving me nuts!

* There are no check engine codes.

* I am very familiar with the cold start misfire/knocking problem. This is not that problem. (see the video in the link below for specific examples).

* The problem started e few months ago as a very intermittent issue that only occurred in certain load conditions. Generally in low speed (7 - 25mph) high torque situations or for a brief period when you let off the gas petal. Now it happens on demand.

* This problem is easily created at idle each and every time the HV battery drops below 2 bars and requires charging. The engine change is immediate and starts and stops in sync with the extra load of the HV battery charge cycle.

The problem also occurs when you drive it under load... so it's easy to assume its load related... BUT is does not do it under load when the car is ran from a cold start. There is a window of time ~ less than 1 minute where the car runs with the ICE under load and the (raptor) sound is not present. Once the car is up to temp (or whatever constitutes this delay) the problem is present. Under very heavy loads (~floor the gas petal) the problem is not present or not distinguishable.

If it is simply load related... what is the solution? What can I do to narrow the issue and fix the problem?

I am trying to focus on the maintenance mode idle test as this is repeatable and does not involve other driving variables. This is why I am trying to understand what happens then the HV charging process is initiated.

Do you know any details on what happens when the HV charge process is present?

Troubleshooting Performed to date:
* I have cleaned the intake manifold (this was done about a month before this problem surfaced).
Prior to cleaning the intake manifold the car was shaking and misfiring under certain high torque condition.
Once I cleaned the intake manifold the problem was fixed and I had no more check engine incidences and the shake was gone.


* I have two (2) 2010 Prius cars. I have swapped the following parts with the working 2010 Prius:
No change has made a difference in the problem.
.
* Coils and spark plugs
* VVT solenoid
* Cam Sensor
* EGR Valve
* Injectors
* MAF Sensor
* MAP Sensor
* Evap Control Valve

The other odd thing is the car sometimes makes a hissing sound. The sound comes and goes. It changes with engine RPM. In the last week it is gone. The problem was present before the sound and it may not be related. I have not been able to determine the source of the sound... several people have tried to find it by checking to exhaust and intake leaks... we simply could not find the source when the problem was present.

We checked the in the exhaust with a smoke test... nothing. We checked with the propane trick and we checked with carb cleaner looking for intake leaks. We also tried to find it with a stethoscopes and of course we tried with hand, eyes and ears... we could not find it.

You can see some videos of the issue in my original thread:

http://priuschat.com/threads/2010-prius-knocking-raptor-sound.157586/#post-2251948

Thanks so much in advance for your help!

 

There is no check engine codes or warning lights.
I changed the spark plugs and coils to fix another issue about a month before this problem. I have also swapped these parts from a know working Prius to confirm those parts are not the solution. See my post just prior to this on for further details.

Thanks for you help... this problem is driving me nuts!

 

Thanks bisco... Up until this problem started if was running fine (just like my other one).

Any help or insight is much appreciated.

 

I went over all the hoses... could not hear or feel the source. Usually when you have a leaking hose you can find it with propane or by spraying carb cleaner over the leaking area. The leak with suck up the spray and the rpms will increase to denoted the bad area.

I tried this and could not find it. I sprayed all over the hoses, the intake manifold area with no luck.

Is this what you had in mind?

 

I assume it has to be in park... otherwise the wheels would start to turn from the torque generated by M1.

This is a very important feature (charging while parked) otherwise the car could easily kill the HV battery while parked in the driveway with the AC running.

(I guess there is no way to unpost... it seem the information you posted a little later fully explained this operation... Sorry I did not see that before I posted the above)

 

Very strange indeed... it seems like the algorithm that detects misfires also works hard to limit how often the check engine light is enabled.
In the year that I've had these cars I've always had the feeling the software guys were working hard to hide the misfires. It seems this problem is a poster child for this discussion.

Today I posted a new update on the problem using Techstream that shows a ton of misfires being detected by the engine ECU but for whatever reason it doesn't fire the check engine light. The interesting thing is how it counts up to 75 or 100 per cylinder and then resets to 0. The other interesting part is how it only shows misfire on cylinder #1.

You can see the details here 2010 Prius Knocking (Raptor Sound) | Page 2 | PriusChat