Prius engine

Aug 17, 2005 7 Replies

Is it normal to feel a slight shudder when the gas engine turns on or off?


Mine did this several times early-on (last February, March) and once again just the other day. It only does this when it is cold which is counter intuitive since it behaves more like the run-on I've experienced with overheated engines.

Ones built in Israel shudder! You're screwed again! JS

This sort of post doesn't belong here. Please stop.

Yes. Many people have reported this; see for example

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and
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What I can't figure is what the conditions that cause it are. I've always felt it when getting near a stop, but often it doesn't do it at all. Huh.

Mike

It sometimes happens when you stop a little more quickly than the gradual stop that you get used to doing when driving the Prius. When you stop quickly, often a tiny bit of gas is left in the ICE when you have stopped and the computer signals the ICE to shut down. This results in a very slight equivalent of "dieseling" or run-on which gives that slight shutter. Forget about it.

My GUESS is that it's not dieseling at all, but is really the motors that make up the transmission (CVT) turning out of step with the spinning down gas engine. IIRC, the motors spin the gears in the CVT to cancel out the gas engine's rotation. If the engine stops quicker than the electronics expect, it could cause that interesting noise as the motors turn over the engine.

I could be wrong, of course.

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