Toyota Prius Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
At approximately 4000 miles the shut down of the ICE, when I came to a stop at a light, became "noticeable. " The outside temperature was high and I was running the A/C. It felt as if the computer could not decide if the ICE should shut down or not. This "rough shut down" has continued off and on since early September. Again it iseems to occur more often when the outside temperature is high, but has occured when temperatures were about 70. Has any one else experienced this phenomenon?

I did have the Toyata dealership look at this when I had the first oil change and they said it was normal. Personally, I do not know if they understood what I was describing.
 

·
Registered
Joined
·
2,243 Posts
The ICE shutdown is a little rough when the ICE has not fully warmed up, such as in the first 5 to 10 minutes of driving. That's about the only time I notice it with my 04.
 

·
Registered
Joined
·
7,161 Posts
It's normal. I suspect it is the ICE burning off residual fuel vapors that may have collected in the intake manifold and the charcoal pack in the air filter canister on account of the Atkinson cycle. I believe it is running the engine with spark but no fuel to be sure this occurs.
 

·
Registered
Joined
·
2 Posts
Discussion Starter · #4 ·
Thanks, for the info. I do recall that several of these occurrence were with in 5 minutes of start up. I will take note in the future if that is always the case.
 

·
Registered
Joined
·
74 Posts
I Thought that was normal

Isn't the generator under load nearly all the time? A loaded generator connected to a small engine usually produces a sort of "shudder" at shutdown.
 

·
Registered
Joined
·
7,161 Posts
It depends on how one's generator is shut down. Usually when a vehicle's engine is turned off, spark AND fuel is cut. With no spark, any remaining fuel vapor isn't ignited therefore not burned for power.
For a portable generator, most likely one is cutting off the fuel supply. If the engine has a magneto, then the engine is most likely still provided with spark, thus will shudder as the remaining fuel vapors are burned off.
 

·
Registered
Joined
·
5 Posts
DanMan32 said:
It depends on how one's generator is shut down. Usually when a vehicle's engine is turned off, spark AND fuel is cut. With no spark, any remaining fuel vapor isn't ignited therefore not burned for power.
For a portable generator, most likely one is cutting off the fuel supply. If the engine has a magneto, then the engine is most likely still provided with spark, thus will shudder as the remaining fuel vapors are burned off.
So what you are saying is that the spark plug is always working as long as the car is in "ready" mode or on. Or does the spark plug shut off with the fuel during idle also.
 

·
Registered
Joined
·
7,161 Posts
I'm saying that when the system shuts down the engine, it may still feed spark for a bit until the engine is completely shut down. I doubt spark is left to operate during all times the engine is spinning. I was giving examples of how other engines shudder when the fuel supply is cut, but the spark is not. When spark is cut, the engine is usually powerless on the spot, with remaining spin being the inertia of the flywheels and such, with the exception of when gasoline engines have issues and start dieseling, which is not a normal condition.

When I turn off the spark to my lawnmower, it dies immediately, no shudder occurs. However, when I cut the fuel supply and let the remaining fuel in the fuel bowl and carburator burn off, the engine sputters until all fuel available is consumed.
So, in conditions when the ECUs determine conditions might leave hydrocarbons remaining in the intake system, spark cut may be delayed until all fuel vapors are consumed.
 

·
Registered
Joined
·
11 Posts
So far,not noticeable on my 2007 ..

only has 500 miles on it, but with my 2003 Prius...you could feel the car "buck" when the ICE came on. It was always that way from the day it left the ealership..
 

·
Registered
Joined
·
991 Posts
I've experience "rough" ICE shutdown when my car is in park, and the generator kicks in to charge the battery and I happen to be turning off the car. (Basically what most of the people above have already stated). Nothing to really worry about :)
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top