Yeah this is why I decided I approved when I saw the hypermiler trick of parking so you can just drive out. I now back in to most spaces (except at home where it's street parking, and sometimes you get what you can, mostly parallel parking), so I can just start and go, and I'm on the move by the time the ICE even starts up. (Especially as I can usually back in using EV mode while backing out tends to burn gas....) If I have to back up it'll kick in well before I'm moving forward. And my experience is that if you hit the power button a couple of times with your foot off the gas, it actually starts ("ready" light steady on) faster than just going from "off" to "on". Sometimes it starts burning gas before you can even shift into drive (at least in cold weather or when battery is low) because of the slight delay before it's "ready", while the computer seems to be good to go my way so you can generally be moving before it starts burning fuel.

But 2 winters I've never had the disturbing shuddering start of this thread. No clue if any of it is my trying to be moving when ICE comes on, variation in cars, or other.

 

I park so I can just drive out too... but it has nothing to do with hypermiling, and more to do with my irrational fear of running over someone while driving in reverse. when I do have to back up, I have to check about 30 times before I'll back out, haha

I have to admit, I never thought of just going as soon as (if not before) the ready light comes on.

 

Well you can't go _before_ the ready light's on, because you're not actually "on" yet (and if you shift too fast it'll complain about the car needing to be in park when you power on). But I've never seen any reason since I had a car that could run on electricity alone that I should sit there burning gas for no reason before I start driving.

 

I just experience my first "shudder" this weekend. ~3000 miles on the car. It wasn't too cold in my garage though. I had my MFD set to temperature and noticed it said 50F as soon as it came on. Doesn't seem like this problem is related to sub-freezing temperatures.

 

I've had the problem a few times as well, it seems to happen when it is below freezing. It almost sounds like the exhaust or manifold is rattiling ('chattering'), it only happens for a second and then stops.

 

This morning (in 30deg F weather), I had a very mild version of this occur 2 times, each before the car had warmed up (within 5 minutes of starting). Both of these instances occured as I was slowing down approaching a red light. Here were my conditions:

* Traveling 20 MPH as red light appears.
* ICE is running at cold-idle speed (probably around 1000 RPM).
* Breaks are gently pressed to slow vehicle as red light nears.
* As speed decreases below 10MPH, ICE appears to be put under a load, RPM appears to decrease, and ICE starts to shake progressively worse (though not severe) until vehicle stops.
* Once stopped, RPM goes back to around 1000 and ICE is smooth.

From what I could deduce, the power split device seemed to allow the ICE RPM to drop too low as the vehicle slowed down, thus causing the ICE to approach (but not reach) a stall point. I believe that the violent shake mentioned in this post is a more severe form of this, where the engine actually REACHES the stall point, but the power split device doesn't let it stop like a normal ICE would.

If this is confusing, picture an engine connected to a hand crank. A person can turn the crank and cause the engine to rotate. Assume a minimum RPM of 800 before the engine would stall under its own power. Now, picture the person turning the crank at a constant 400 RPM, but with no fuel going to the engine. Fuel is then supplied to the engine, causing it to fire. The person is strong and prevents the engine RPM from going above or below 400 RPM. At this RPM, severe misfiring is occurring, causing the engine to shake severely, but not stall because of the person controlling the hand crank.

 

I may be off the main subject here. I have a stop sign near the house. I never liked the cold engine pulling against the brakes on a cold engine. Stopping the gas ice cars I owned I would always pull the gear lever to low to prevent this. With the TCH I pull the level to the brake position when i'm down to about 15 to 20 miles per hour. I seems to work the same. If the engine is warm I use method only if the mpg indicator is on 60 or less. If it's in the EV mode I leave the lever in drive to stop.

I have had a rare few times I have started the car in the mornings. The engine seemed to vibrate like it was running too rich. It would clear up in a few seconds as I would back up.
I only remember it happening maybe three times during this winter.

 

andrewbmoore — I have also had a few rough ICE starts and rough ICE stops (but not many). I think that the occasional shaking when stopping the ICE is a consequence of Toyota's "ICE-stop" strategy occasionally not working as intended. Their patents discuss how to stop the ICE without significant engine vibration. The occasional shaking when starting a cold ICE might also be a failure of their algorithm; i.e., a programming error. MG1 is involved in this strategy, and it is possible (as you suggest) that it is occasionally holding the ICE's rpm too low while the ICE is still receiving fuel and spark. Other possible reasons also occur to me. For example, the fuel injector and spark control algorithms might contain a programming error that sometimes rears its ugly head. It's difficult to say why this sometimes happens.

Stan

 

I was just thinking what if the shaking engine was too lean. No, it would at a unsteady rpm and then die. It's probably on the slightly rich side but maybe not the exact fuel mixture for the present cold temperature.

Mine did it again today. I'm almost sure it was my fault. I pressed the brake and power button. I saw the dash light up and quickly moved the level into Drive. The engine started immediately but was also shaking some. Normally it don't start at that point. It will start after I have rolled back about 8 to 12 feet. Once started in reverse the engine is very smooth at normal idle unless it's cold. Tomorrow I will wait for the Ready indication then place it in gear.

It's very rare I feel any shudder when the engine stops. If the engine shuts down late when near a red light like when i'm down to 5 or 10 miles per hour with the brakes on. Usually I coast far enough back that the engine will shut down at 25 to 35 miles per hour and can't even be felt.

 

Do you have Alcohol in your fuel? My will idle ruff and make some noise when starting.


Bill