The 2008 Prius I have when it comes to a stoplight all of a sudden the car shakes

How many miles?
Have you ever replaced the Transaxle ATF?

 

Does it do it all the time or mainly when the car is still cold?
If only when cold, it could be because it has an Atkinson cycle engine. The intake valve is held open a little too long, so that when the piston moves up for the compression stroke, a little of the gas-air mixture can escape. In engineer-speak, the modern method is known as "livic" -- late intake valve closure. Then the spark plug does its thing -- sparking -- and the piston takes advantage of the combustion with a full power stroke down the cylinder. And then the exhaust stroke does its clean-up job. This uses the last bit of fuel in the cylinder and reduces emissions.

 

Shaking may be drive ability issue at low throttle. Which immed. makes me think a good throttle body cleaning may help. Probably has never had it cleaned before.

Use this method here and let the engine run and you can rev it up a little to and see how it behaves and sounds:

My car shook a little when it was brand new but the older it gets the better it runs. But I have always used high quality synthetic oil like Mobil 1 since new. I think that really helps the smoothness of the engine over the life of the car. I suspect your car has spent its life on dyno oil. Running dyno oil creates more soot which ends up in the throttle body. Another benefit to running higher quality oil.

I'm running some really high performance oil right now and notice major improvement in the general performance and sound of engine. The engine on/off is almost seamless. This stuff:

Redline Motor Oil 10-30

 

I have this issue too. It seem that when the car is stopped at a light and the ICE shuts off.. the car shakes pretty hard. I am comparing it to my wife's 2010 3rd Gen. Prius which is smooth when the ICE shuts off at the light. She has around 80K miles to the 90K I have on my 2008.. My question is, Is it normal to shake hard on the 2nd Gen Prius compared to the 3rd Gen?

 

I recall an earlier thread about this and it has something to do with the engine pre-positioning itself for the next start cycle. It can "hunt" around a bit when it does this if it doesn't get it on the first try. Not sure if a throttle body cleaning would help, but it can never hurt (if done properly).

 

One time I thought I was going to have to take the car into the Dealership....

I ALWAYS Pulse~n~Glide as much as possible to play the Consumption Game.. (my screen currently shows 53.1 Average) ...

So I'm Gliding down hill then off the freeway continuing down hill to a red light... When I stopped the car was shaking so bad acting like it didn't know if it wanted to shut off or run...

Later I read that if the HV Battery is overcharged then it will run the MG1 to blow off a little charge to make it a little more manageable ..


I'm hoping this is good information ....

I'm quite happy with this new addition to our family but it is a little different than the wife's 3rd gen Prius. Hers is smoother, quieter and seems to be a little more refined than mine. On a side note, I find my car more comfortable than hers (the seats and the ride).

 

No. The transition is barely noticeable.

Also, I do not believe that story about MG1 running to burn off battery overcharge. The HV battery is never overcharged, the battery ECU sees to that. It does happen that the engine will cool off sufficiently that the engine ECU will run a small bit of fuel until it comes back into temperature range, and this would tend to happen with the battery full and little engine load. I have never seen the former case, and do see the latter case from time to time.

So far shaking at engine shutdown seems to be mainly due to some combination of spark plug, injector, or throttle problems, from what I read here.

 

Too many people here agree in their own words about the MG1 running to burn off battery overcharge... I must have read it 6-7 times here and I concider myself a "New Member" as it says on my Avatar...

"if battery state of charge is too high, then the motor-generator will turn the engine crank to burn off the charge."

at 90K I do plan to replace the plugs early and clean the throttle body thing and run through some injector cleaner..

 

i wonder if the small amount of driving is leading to engine contamination problems.

 

Repetition does not make a truth. Perhaps someone has a link to more in depth info on the MG1 notion. I'm always ready to learn, especially when it seems counterintuitive.

 

I see you did a search and your disputing it with Patrick Wong now. so I'll leave it to him to learn you something counterintuitive ... Lol!

"
Patrick Wong said: ↑
If you see 8 green bars, the engine is being spun by MG1 to remove excess traction battery charge.
Click to expand...
Is that really how it works? I see 8 bars of charge on every drive I take, and never see this happen. I do see that charge current is reduced to zero when the battery is full, and regen no longer occurs, which is logical.

It does not make sense that there would be a systematic means of overcharging the battery that then requires dissipation. What are the conditions which require this "excess" to be wasted as heat?

Is it not that the engine has dropped out of S4 and needs to reheat? That I have seen, particularly when the engine is not used due to long coasting."

 

when you are braking, if the battery is full, it is burning off what it otherwise would store. there is probably an overlap when you come to a stop, until it equalizes.

 

in my '08, when i came off the highway with 8 full bars, and would enter my office park at 15 mph, the ice would run for the entire half mile. happened every night.