Need some answers

[robinredbreast]

Let me try to explain okay 8 out of 10 times when the ICE starts in Park or if the heater makes the ICE kick on in Park the ICE can be warm or cold doesn't matter . When the ICE starts up it gives you a VERY good jolt then lurches forward a bit then rolls back a few inches. Only does this in Park not Drive. Is this normal.

[richard schumacher]

Are you certain that the car actually rolls some distance, as opposed to just jerking as the ICE starts?

You've piqued my curiosity: do you spend a lot of time with the car ON and in PARK? If so, why? (I hope it's not to warm up the car in cold weather; that is completely un-necessary, and wastes gas.)

[robinredbreast]

You can feel it move forward like it is in Drive then it feels like it hits a gear or something then rolls back. I dont think the wheels are rolling .ICE start VERY abrutly As For sitting in park that is when I pick up my kids from school.

[efusco]

That does not sound normal...have it checked.

[8AA]

I guess it depends on your definition of "very good jolt."

Then the car is in park, the transmission is mechanically locked, but there is a little bit of play in the locking mechanism. You can demonstrate this by rocking a car that is in park (but doesn't have it's parking brake on); the car will roll forward and backward an inch or so.

Think of it as having wheel chocks in front of and behind the wheels, and there is a little bit of a gap allowing you to rock the car. If the car is resting against the rear wheel chock and the ICE starts, there is a small amount of torque that will transmit through the Power Split Device and make the car roll forward. It will hit the forward chock, stop, and then roll back to it's resting position on the rear wheel chock. If the parking brake is applied, you might feel the ICE kick on, but the car should not roll forward. It is probably only happening 8 times out of 10 because the 2 times that it doesn't happen the car is on more of an incline, and is firmly resting against the front or rear "wheel chock." The reason that this doesn't happen when you are in Drive, is that unless you are moving, you are probably holding the car stationary with the brakes.

All this said, I've noticed the same thing on my car when I'm parked in front of my house. I'll press the power button and sometimes I won't immediately put it into Reverse because I'm putting something away. The ICE kicks on after it's slight delay and the car rolls slightly forward. I wouldn't call it a "very good jolt," but that is just my perception. It would be great if you could find another Prius owner nearby that you could compare cars with.

[heliotropehead]

I've been jolted too! Twice thus far and both times while getting coffee! Typically I'll put the car in park while waiting in the drive-thru at the local coffee house. The first time I nearly peed my pants, as I thought the car was going to drive away with me and/or hit the person behind me. It's not a huge jolt, but it sure is felt! I've started leaving my car in drive with my foot on the brake and voila no more jolts!

[Hytec]

I assume that the jolt is due to the initial torque of the ICE being turned over by the starting motor. Since the ICE is mounted across the car, the jolt would be felt along the car as a fore and aft motion. Hence, the car feels as if it is moving slightly as the ICE is started. My 2005 jolts also, so I doubt if anything is wrong. Although, it was a bit surprising initially, when you were expecting the car to behave more like a golf cart....

[bruceha_2000]

Do you have your foot on the brake when this happens? The only time I felt a jolt of any sort was when I put on the parking brake, but took my foot of the regular brake then pushed Power to shutdown.

[robinredbreast]

This can't be normal When I first got the Prius in July the ICE would start smooth ,but steadily getting worse now have 9000 miles. I read somewhere the ICE compression is let off until its spinning at 1000 rpm .mabe the computer is not letting off the compression at the right time making the engine start with a Jolt enough to spill your coffee in the car. Also not my imagination the engine has been getting louder like it has a leak in the exhaust going next week to have all of this checked.

[jayman]

I've had "the jolt" maybe 6 times since buying the car, most recently in colder weather. I've noticed it's most likely to occur before the ICE is fully warmed up. If I drive for an hour or two at 110 km/h, then go back into the city, the ICE shutdown and startup is almost imperceptible.