Does your car move forward when the ICE cranks?

terryonmac · 11-16-2007, 06:15 PM

I was installing my new Scangauge II and had the power on and in park when the ICE started and I felt the car try to move forward. This is the second time I have noticed this. Is this normal? It is a 2008 model.

paprius4030 · 11-16-2007, 06:25 PM

Yeah sometimes it does this. Not sure if it actually tries to move or it's just the give in the engine mounts or something like that?

Neicy · 11-16-2007, 06:30 PM

It doesn't really move, but it feels like it does. Once you understand how the Prius transmission is set up you will understand what's actually going on when the ICE starts - and stops - especially when cold and/or new. Mine always does that little rock when starting up, and I'm now used to it. Here's one thread, but if you search for shake, shutter, stutter or something similar you will find several threads.

http://priuschat.com/index.php?showtopic=4...hakes+at+a+stop

hoop · 11-16-2007, 07:09 PM

<div class='quotetop'>QUOTE(paprius4030 @ Nov 16 2007, 07:25 PM) [snapback]540733[/snapback]</div>

Quote:

Yeah sometimes it does this. Not sure if it actually tries to move or it's just the give in the engine mounts or something like that?
[/b]

I believe its just the torque caused by the ice starting.

terryonmac · 11-16-2007, 07:17 PM

Ok, torque makes sense. I have felt the shutter at while stopped but I have read about that and ignored it when it happened. I'm thinking about naming it Herbie as it seems to have a life of its own.

paprius4030 · 11-16-2007, 07:36 PM

If you name it Herbie don't forget to paint 53 on the side of it LOL, At least i think that's the number

statultra · 11-16-2007, 07:42 PM

its torque reaction of starting the engine.

but if you manage to get the parking pawl engaged, the torque reaction comes less

daniel · 11-16-2007, 08:26 PM

The engine of the Prius is never disengaged. At all times if the engine is running, 60% of the torque goes to MG2 and thus to the wheels. If there is anything preventing the car from moving (such as your foot on the brake) then instead of the car moving forward, MG1 will turn backwards. The car can intentionally spin MG1 backwards to prevent the engine from turning the wheels. But it sounds to me as though what's happening is that when the engine starts that torque is getting to the wheels before the car can react to counter-act it.

Others have reported feeling the same movement. I've never noticed it, though I do feel a bit of a shake sometimes when the engine starts or stops roughly.

Tenebre · 11-22-2007, 10:26 AM

<div class='quotetop'>QUOTE(daniel @ Nov 17 2007, 02:26 AM) [snapback]540760[/snapback]</div>

Quote:

The engine of the Prius is never disengaged. At all times if the engine is running, 60% of the torque goes to MG2 and thus to the wheels. If there is anything preventing the car from moving (such as your foot on the brake) then instead of the car moving forward, MG1 will turn backwards. The car can intentionally spin MG1 backwards to prevent the engine from turning the wheels. But it sounds to me as though what's happening is that when the engine starts that torque is getting to the wheels before the car can react to counter-act it.

Others have reported feeling the same movement. I've never noticed it, though I do feel a bit of a shake sometimes when the engine starts or stops roughly.
[/b]

The OP stated that the car was in park.

patsparks · 11-22-2007, 11:19 AM

Because I always engage the parking brake and don't rely on the parking pawl I never feel this, yes even in the garage. I think it is the car moving until the park pawl engages if it is left on top of a tooth. It's just like an automatic car pulls forward except the Prius has the affect in park (momentarily) when the park brake isn't on.

11-16-2007, 08:26 PM	#8
daniel Cat Lovers Against the Bomb Join Date: Feb 2004 Location: Spokane, WA Posts: 9,147 My Car: 2004 Prius Package: #6 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	The engine of the Prius is never disengaged. At all times if the engine is running, 60% of the torque goes to MG2 and thus to the wheels. If there is anything preventing the car from moving (such as your foot on the brake) then instead of the car moving forward, MG1 will turn backwards. The car can intentionally spin MG1 backwards to prevent the engine from turning the wheels. But it sounds to me as though what's happening is that when the engine starts that torque is getting to the wheels before the car can react to counter-act it. Others have reported feeling the same movement. I've never noticed it, though I do feel a bit of a shake sometimes when the engine starts or stops roughly. __________________ Daniel ---------------------- Primary car: Zap Xebra SD: 100% electric car. 1.9 cents per mile, using electrons generated from water power. (The Prius is my gas guzzler, used when I have to travel farther than 35 miles in a day.) "If voting changed anything, they'd make it illegal." -- Emma Goldman "Anyone who has ever looked into the glazed eyes of a soldier dying on the battlefield will think long and hard before starting a war." -- Otto von Bismarck

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11-16-2007, 06:15 PM	#1
terryonmac Join Date: Nov 2007 Posts: 6 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	I was installing my new Scangauge II and had the power on and in park when the ICE started and I felt the car try to move forward. This is the second time I have noticed this. Is this normal? It is a 2008 model.

11-16-2007, 06:25 PM	#2
paprius4030 Senior Member Join Date: Aug 2004 Location: Pocono's, Pa. Posts: 1,046 My Car: 2008 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	Yeah sometimes it does this. Not sure if it actually tries to move or it's just the give in the engine mounts or something like that?

11-16-2007, 06:30 PM	#3
Neicy Senior Member Join Date: Apr 2007 Location: Wakefield, MA. Posts: 781 My Car: 2007 Prius Package: G Touring Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 5	It doesn't really move, but it feels like it does. Once you understand how the Prius transmission is set up you will understand what's actually going on when the ICE starts - and stops - especially when cold and/or new. Mine always does that little rock when starting up, and I'm now used to it. Here's one thread, but if you search for shake, shutter, stutter or something similar you will find several threads. http://priuschat.com/index.php?showtopic=4...hakes+at+a+stop

11-16-2007, 07:17 PM	#5
terryonmac Join Date: Nov 2007 Posts: 6 My Car: Package: Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	Ok, torque makes sense. I have felt the shutter at while stopped but I have read about that and ignored it when it happened. I'm thinking about naming it Herbie as it seems to have a life of its own.

11-16-2007, 07:36 PM	#6
paprius4030 Senior Member Join Date: Aug 2004 Location: Pocono's, Pa. Posts: 1,046 My Car: 2008 Prius Package: #2 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 1	If you name it Herbie don't forget to paint 53 on the side of it LOL, At least i think that's the number

11-16-2007, 07:42 PM	#7
statultra uber-Senior Member Join Date: Dec 2005 Location: cape coral, FL Posts: 575 My Car: 2005 Prius Package: #9 Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 0	its torque reaction of starting the engine. but if you manage to get the parking pawl engaged, the torque reaction comes less

11-22-2007, 11:19 AM	#10
patsparks Uneducated bird-brain Aussie Join Date: Jul 2007 Location: Adelaide South Australia Posts: 4,905 My Car: 2004 Prius Package: Base Nominated 0 Times in 0 Posts TOTM Awards: 0 Friends: 17	Because I always engage the parking brake and don't rely on the parking pawl I never feel this, yes even in the garage. I think it is the car moving until the park pawl engages if it is left on top of a tooth. It's just like an automatic car pulls forward except the Prius has the affect in park (momentarily) when the park brake isn't on.