[leebek]

For two days now, more or less, when at a complete stop in electric mode, occasionally I can feel the car shuddering ever so slightly. AFAIK, the gas engine is not in use, so I cannot think of what could be causing it. There are no idiot lights on the dash to warning me of a problem. It does not do this consistantly, so taking it to the dealer would be a waste of my time and theirs, I think. I have an 02 classic, 8K miles of mostly city (battery) driving. Has anyone experienced this? Did you have it looked into? Any suggestions? :?:

 

[citicar1976]

Re: Shuddering at stops

Leebek, is it the car that is shuddering or just the steering wheel? Sometimes, the gas engine will shudder a bit when it is about to shut down to go into electric mode. That is normal. If the gas engine is off and the car shudders, it could be that the car is going in and out of "creep" mode. If the brake pedal is at a certain point, the car will apply power, on and off, to the electric motor while the car is stopped. You can check for this by watching the energy flow monitor. The arrows, from the electric motor to the wheels, will appear and disappear while you are stopped. I noticed that as my Prius got older, I had to apply more pressure to the brake pedal to keep it from going into "creep" mode.
If it is the steering wheel that is shuddering, it could be the electric power steering.

 

[moocatdog]

For two days now, more or less, when at a complete stop in electric mode, occasionally I can feel the car shuddering ever so slightly. AFAIK, the gas engine is not in use, so I cannot think of what could be causing it. There are no idiot lights on the dash to warning me of a problem. It does not do this consistantly, so taking it to the dealer would be a waste of my time and theirs, I think. I have an 02 classic, 8K miles of mostly city (battery) driving. Has anyone experienced this? Did you have it looked into? Any suggestions? :?:

I've experienced this as well. I mentioned it in a post a couple of months ago and John1701a said he thought it would stop soon after the break-in period. I'm now at 3200 miles and, while it doesn't happen very often, I do still notice it on occasion.
Drive happy,
Moo

 

[mrv]

For two days now, more or less, when at a complete stop in electric mode, occasionally I can feel the car shuddering ever so slightly. AFAIK, the gas engine is not in use, so I cannot think of what could be causing it. There are no idiot lights on the dash to warning me of a problem. It does not do this consistantly, so taking it to the dealer would be a waste of my time and theirs, I think. I have an 02 classic, 8K miles of mostly city (battery) driving. Has anyone experienced this? Did you have it looked into? Any suggestions? :?:

Put your foot firmly on the brake (press harder).

The Prius will simulate the automatic
transmission creep if you do not press
hard enough on the brake pedal. What
you're probably feeling is the creep
fighting with your brakes.

If you press a little harder, the
creep will turn off, and you shouldn't
feel the dancing anymore.

 

[Riffraft]

I am getting the same thing and I don't think it is brake shudder. Mine is most noticeable the first time I stop after going just a short distance in the car. I will be setting stopped for a matter of seconds then I will feel a distinct shudder when the Gas engine cuts off. After it has warmed up I still feel it occasionally, but not nearly as much. Then when it has been running quite awhile I don't get it it all.

I must admit I wondered about the Gas Engine cutting off and on as much as it does prior to me getting my Prius. If you were to cut off and on a normal cars engine that way I can't imagine that it would be good for it. I think you would get the same effect I experiencing in my Prius as sometimes the engine would not cutoff cleanly, especially when the car is cold.

 

[mrv]

I am getting the same thing and I don't think it is brake shudder. Mine is most noticeable the first time I stop after going just a short distance in the car. I will be setting stopped for a matter of seconds then I will feel a distinct shudder when the Gas engine cuts off. After it has warmed up I still feel it occasionally, but not nearly as much. Then when it has been running quite awhile I don't get it it all.

I must admit I wondered about the Gas Engine cutting off and on as much as it does prior to me getting my Prius. If you were to cut off and on a normal cars engine that way I can't imagine that it would be good for it. I think you would get the same effect I experiencing in my Prius as sometimes the engine would not cutoff cleanly, especially when the car is cold.

yes, there is some residual gasoline
that may be in the system when the
gas engine is shut off. it's just
easier and cleaner to have the gas
engine burn it (and sputter) than to
vent it or to leave it in the engine.
this burn-off may be what you're
experiencing.

as for the on/off nature of the
Prius, see:
http://www.john1701a.com/prius/prius-mi ... is_harmful

(think of a traditional car, running
its engine idling all those times
that you're at a stop, or coasting
downhill - all that extra work can't
be good for a traditional car's engine,
either!)

 

[moocatdog]

shudder update

Prius friends,
I've been paying very close attention to this lately and I don't believe the shudder I'm feeling is the result of faux "creep." It happens only occasionally and seems to be most likely to occur while the car is still warming up. A few days ago I noticed it after pulling into a parking stall after a short trip to the store. Today, after driving at freeway speeds for approximately 30 minutes, I tried various amounts of pedal pressure--even allowing the car to creep--and couldn't get the same sensation. I'm pretty confident that what I'm feeling is somehow engine idle and temperature related. My next test will be to see if I can get it to shudder while in "P." Wouldn't that definitively rule out faux creep? Maybe others that are experiencing this can do some cold engine/warm engine testing to give our resident experts (MRV, John1701a, Frenchie, et al) more info. I'm optimistic that this is normal and nothing to worry about, but it sure has made me curious.
Drive happy,
Moo

 

[frenchie]

Very probably, what you're noticing is just the start and stop transitions of the engine (when idling it's so silent you can think it is already at stop, especially if you listen to the radio...). Remember that there is no clutch in a Prius, and always a mechanical link (via the Power Split Device) between the engine and the wheels. It should be considered as an engineering miracle if, when at stop, the engine cuts off and you don't experience any vibration.

 

[moocatdog]

Very probably, what you're noticing is just the start and stop transitions of the engine (when idling it's so silent you can think it is already at stop, especially if you listen to the radio...). Remember that there is no clutch in a Prius, and always a mechanical link (via the Power Split Device) between the engine and the wheels. It should be considered as an engineering miracle if, when at stop, the engine cuts off and you don't experience any vibration.

Frenchie,
I would be very surprised if the vibration I'm trying to describe is the result of stop and start transitions. It happens in the blink of an eye, similar to what many commonly refer to as an engine "missing." Perhaps a better word than shudder is stutter, as it is quick, subtle, lacks rhythm and is felt more than heard. Would a PDA connection such as efusco is devising capture data on such an event?
Drive happy,
Moo

 

[Phoenix]

Drivetrain Shudder

I have infrequently experienced something like a backfire when the gasoline engine shuts down, which is accompanied by a shudder. Actually, it sounds more like a valve opened up during the compression stroke -- like "pshhhhh" (explosive at the beginning and tapering off). This only happens when the outside weather is in the 80-90 degree range. I just figured it was an oddity of the Atkinson-cycle engine. Is that the same thing? Is this normal?

 

[moocatdog]

Re: Drivetrain Shudder

I have infrequently experienced something like a backfire when the gasoline engine shuts down, which is accompanied by a shudder. Actually, it sounds more like a valve opened up during the compression stroke -- like "pshhhhh" (explosive at the beginning and tapering off). This only happens when the outside weather is in the 80-90 degree range. I just figured it was an oddity of the Atkinson-cycle engine. Is that the same thing? Is this normal?

Phoenix,
I suspect what you are describing is the normal process of the ICE burning any excess fuel as it shuts down. I recognize that when it occurs and this is not the same thing. Thanks, though.
Drive happy,
Moo

 

[efusco]

I'm willing to bet pretty dang good money that what is happening is this....First, check something next time it happens.....

If you're not already on the Energy Screen switch over to it immediately when you notice the shudder....is the battery in the green zone? If it is then what i"m about to describe is what's happening....

The Prius doesn't like the battery to be too full. If you juice it up toward the slow mark, esp. after some long hills or a long braking period to come to a stop, the ICE will initially shut off, it'll then restart, and shut down and restart for several cycles (5 or 6 is the most I've experienced at a time). The motor obviously uses the HV battery to spin up the ICE and that causes a drain, so it spins up the ice, the ice shuts down, then repeats the cycle several times. This effectively drains the battery a bit in preparation to accept more incoming charge once the ICE starts up in earnest.

--evan

 

[RSnyder]

Re: Drivetrain Shudder

I have infrequently experienced something like a backfire when the gasoline engine shuts down, which is accompanied by a shudder. Actually, it sounds more like a valve opened up during the compression stroke -- like "pshhhhh" (explosive at the beginning and tapering off). This only happens when the outside weather is in the 80-90 degree range. I just figured it was an oddity of the Atkinson-cycle engine. Is that the same thing? Is this normal?

Well, the intake valves on the Atkinson cycle engine do remain open for about the first 1/3 of the compression stroke. That shouldn't cause a backfire though.