Jerking when the fuel engine turns on

This was normal in my 2009 over the 225,000 miles I had it. On my 2017 Prime it is less noticeable. It usually happened when I was sitting for long periods with the air on and the engine finally kicked in to charge the battery on the ‘09.

 

Our Prii (I have had three) implement "neutral" using software control of the MG opposite the Engine on the Hybrid Synergy Drive. That MG is controlled to spin in reverse to compensate for the engine running forward so that the torque applied to the drive shaft is minimal. This is not perfect and when transients occur (like the engine starting up which requires some counter torque to spin the ICE), some torque is momentarily applied to the driveshaft and you will feel some movement.

 

I have a 2017 Prius 2 and Yes mine moves forward about 2 or 3 inches when the engine fires up and it’s a normal thing as it’s been doing this for awhile.

 

I've noticed for my Gen 3 they actually made the ECM coordinate with the brake ECU. When it is about to start the engine and it's parked, it applies the brakes first, to minimize any roll of the car. If things are quiet enough, I can hear the brakes apply, and pretend I have precognition of when the engine's going to start.

I don't know if they added that only in Gen 3 or if Gen 2 did it too. I know my old Gen 1 didn't.

 

Is the parking brake on?

 

One of the cylinders might misfire.

 

You could at least wait until you get home to do that ! lol