Jolt when petrol engine switches off

Heavier oil in the engine will cause it to jerk. Don't know the code. Perhaps someone else can look that up for you.

 

Mine does this too sometimes. Seems to be more noticeable when he engine is cold. I am using Mobil 1 0W30 also.

 

When a Prius turns off the ICE, it burns off residual fuel and spins the ICE to stop at an optimal position for restarting. Sometimes it misses on the first attempt and has to go around for another try, producing a rougher shut down. This is more likely to happen with a new or cold engine.

Tom

 

That's interesting. How is the optimal position calculated? Maybe the position is such that none of the pistons are on the compression stroke (is that even possible?) so to give more time for crankshaft spinup before encountering compression. Might make for a smoother ICE restart.

 

I thought it did this as the car finished its inital warm up. Phase three or something the hyper milers call it.

 

It does, as well as any other time when the ICE shuts down. The shutdown after initial warm up is the first opportunity.

Tom

 

There is a crankshaft position sensor in the engine. Cold or heavier oil will mess up the "estimate" the system uses to have the engine stop close to the correct position. This causes it to miss and do a "go around" for another try. When Pearl was new it sometimes took three or four tries to get it right. She makes it on the first try most times now.