Jerky feelings during phase 1

Rob,

Do I understand correctly that when starting-up first thing in the day,
or after a prolonged stop during the day, you are sitting in the
immobile car and running the ICE specifically and solely to charge the
HV battery?

There is no recognized need or even good reason to do this. Best way
to warm up the ICE is to just get in and drive and get through Stages 1-
3 as soon as possible.

For the most part, you don't need to worry about the SOC of the HV
battery, the computers will take care of making sure that the charge
level is neither too high or low. When you are at Stage 1 the car is
mostly moved using the HV battery. In the first few minutes the SOC
drops pretty dramatically, but that's part of the drill. For this reason,
it is best to arrange your driving style to have 50-60% SOC at the end
of the day when you shut down for the night.

Lastly during Stages 1-3, some shuddering and minor juddering when
the IE shuts down is typical. I've read that it has to do with the
computers making sure the the ICE is aligned just-so to be in position
to restart instantly.

In short, at start-up, just get in and drive.

 

In my PHEV, I try to avoid letting my engine warm up at a stop like this. (providing I think I will need the engine later at all!) Instead, I usually let it warm up once I'm already driving at a low speed. However, I have noticed what you describe on several occasions when warming up stationary.

In the HSD, in order for the engine to run w/o moving the car/wheels, MG1 must counter-rotate at quite a rapid speed. Thus, all the inertia in this system can cause small changes in speed or misfires in the engine to be amplified and felt in the car quite strongly. Knowing the engine is always mechanically coupled to the driveline, unlike most other cars, I think this is just a normal thing for a HSD equipped car.

I have a relatively low mileage (under 30k) 2008 and it has done this, so I assume all do. If you have never experienced it before and are worried, check the obvious: Fuel Quality, Air Filter, Spark Plugs, MAF & Throttle Body Cleanliness, etc.

If you have an EV mode button, press it within a few seconds of going ready, then you can start gently rolling before you press it again to begin warmup. This will likely eliminate (your awareness of) this problem.

 

Yes, the ICE runs pretty roughly during stage 1 (1a?) if you're sitting in park idling after the car has been stopped for a long time (i.e. many hours or overnight). It's normal.

Agreed w/all of the above. Yes, I and probably everyone else here w/a 2nd gen has encountered the intermittent rough ICE shutdown.

 

In many of the threads I have seen, we have debunked the 'need' to warm up the prius. If you really think you need to warm it up, then I would install a block heater.

Lets do the math:
A car not moving (including a STOCK NON PHEV Prius), idling = 0 MPG.
A Prius moving while warming up (since it uses gas AND electric at the same time): 19-40 MPG (depending on warmup satge and terrain).

So like a previous poster said, get in and drive normally and enjoy life!

 

Hi GigaTigga. I suspect that as the car warmed up through preset stages that the power being generated changed somewhat abruptly causing a torque pulse to be applied to the parking pawls.

Try the same experiment again some time, but with the park brake firmly applied, and I'll bet you don't notice any shuddering.

BTW. If you want to go easy on the transmissions park mechanism then you should always use the park brake as an adjunct to the park mechanism.

 

In fact, when the ICE is cold, it's ECM asks the HV ECU for a catalytic converter warm-up. This is why the Engine usually starts within 7 seconds of ready. Once the cat is warm there is abrupt change in parameters in the ECM, (timing, mixture, etc) and it removes the warm-up request bit and the HV ECU shuts the engine down. If there is another reason the engine still needs to run, for instance if the heat is on, it will continue to run, rather than shutting down, but during that transition there is an abrupt jerk I can always feel.

You can feel it even more if you press the pedal not long after it starts. This will cause the RPM to go up while it's dumping fuel into the cat and once it is warm, the abrupt change is even more noticeable.

 

Dumping fuel into the cat?

 

Make sure the oil level is not too high, that can cause rough idling during stage1. Next items I would check is the ICE air filter. It is also about time to replace the PCV valve.

 

Yes, sounds like something that would raise the SPCA's hackles, but in order to meet the low emissions requirements, the Prius manages it's catalytic converter temperature carefully. The ICE actually adjusts itself to waste fuel during cat warmup to ensure it gets up to temp fast. It's a combination of air/fuel ratio, ignition timing, and valve timing. During this period the electric motor is doing most of the work to drive the car.

It doesn't take long. Start your car when cold (with the heat off) and let it idle until it stops, that's how long it takes. Once the cat is warm and there is no demand for heat, the engine will stop.

 

Check when it is convenience for you. It is also about time (120k miles) to change the spark plug.