Polling The Collective Wisdom - Are These Experiences Normal With A Prius?

[ChuckDavis666]

Before subjecting myself to Toyota service for the first time (the local reviews are pretty unfavorable), I thought I'd draw upon the collective wisdom of this community to see whether or not what I'm experiencing with my 2008 Prius is normal.

My Prius (Touring, Package #3) was purchased in February and now has around 2200 miles on it. Before purchasing it I rented a Prius for a week on a trip to California, so I had some experience with the car and knew what to expect from the driving experience. I averaged 46 MPG with the rental car in a mix of mostly freeway and mountain driving with some city driving.

Are any/all of the following normal?

Engine shutdown is sometimes very rough. Occasionally it even seems that the engine is dieseling. (I know that doesn’t make much sense for an engine with electronic fuel injection, but that’s what it feels/sounds like.)

When braking to a stop at slow speeds, or braking while coasting slowly downhill, there is some “chatter” from the brakes.

There may be something wrong with the engine control circuit and/or a sensor:

** One time when I pulled up to a stop the engine cycled on and off every few seconds for around a minute.

** During another full stop the Energy Monitor showed power flowing from the battery to the wheels.

** When I turn the Power on but don’t put the car in Drive, after a few seconds the engine usually comes on, runs for a while and then shuts down. This happens even when the engine (and catalytic converter) are warmed up.

** The engine comes on when I turn the Power on and shift into Reverse. My understanding is that only electric power is used for reverse.

** The engine continues running for several seconds after the Energy Monitor shows it as having shut down at a stop.

** Gas mileage is higher during freeway driving than during city driving. If I do mostly city driving, mileage is around 40-42 MPG. Only by mixing in a significant amount of freeway driving can I get mileage up to 44-46 MPG. I had read that because of regenerative braking and electric boost during acceleration that mileage should be higher in city driving. I am running the tires at 38/40 psi.

** The engine usually comes on whenever I accelerate from a stop, rather than using the electric motor up to around 15 MPH. This happens even during deliberately slow take-offs in a parking lot. I have the impression that if I turn the Power on but don’t put the car in Drive, let the engine run and shut down (see above) and then put the car in Drive and accelerate that the car will use the electric motor up to around 15 MPH.

Thanks in advance for any clarifying or (hopefully) reassuring information that you can provide.

[efusco]

Everything you described is normal...I'll give details below.

Originally Posted by ChuckDavis666

Engine shutdown is sometimes very rough. Occasionally it even seems that the engine is dieseling. (I know that doesn’t make much sense for an engine with electronic fuel injection, but that’s what it feels/sounds like.)

This is normal, esp. in cooler weather, esp. the first time it shuts down after a cold start.

When braking to a stop at slow speeds, or braking while coasting slowly downhill, there is some “chatter” from the brakes.

Sometimes you'll feel a little give as you switch from regen to friction braking (when you hit a bump or when you get below 8mph)

There may be something wrong with the engine control circuit and/or a sensor:

** One time when I pulled up to a stop the engine cycled on and off every few seconds for around a minute.

It may do this when the Energy display battery shows a full green charge...the car is 'dumping' extra battery charge...it wants to maintain a SOC below 80%, if it's getting close to that 80% mark it may cycle the ICE on and off as MG1 does that by using the battery.

** During another full stop the Energy Monitor showed power flowing from the battery to the wheels.

You were not depressing the brake firmly enough.

** When I turn the Power on but don’t put the car in Drive, after a few seconds the engine usually comes on, runs for a while and then shuts down. This happens even when the engine (and catalytic converter) are warmed up.

Yes, the car will always go into S1. If it's nice and warm and the emissions controls are warm enough it will shut down again even before getting to S3 or S4

** The engine comes on when I turn the Power on and shift into Reverse. My understanding is that only electric power is used for reverse.

Correct, but that doesn't mean the ICE won't run and the ICE may be putting additional charge to the battery while you're using it up to go in reverse...just b/c the ICE is running does NOT mean that it's sending power to the wheels.

** The engine continues running for several seconds after the Energy Monitor shows it as having shut down at a stop.

The Energy monitor is not a true reflection of what's going on and low power states may not be displayed.

** Gas mileage is higher during freeway driving than during city driving. If I do mostly city driving, mileage is around 40-42 MPG. Only by mixing in a significant amount of freeway driving can I get mileage up to 44-46 MPG. I had read that because of regenerative braking and electric boost during acceleration that mileage should be higher in city driving. I am running the tires at 38/40 psi.

Common with newer drivers until you learn to take advantage of the hybrid system in city traffic by anticipating stops, allowing longer following distances and learning how to make the best use of the electric drive and when to avoid it.

** The engine usually comes on whenever I accelerate from a stop, rather than using the electric motor up to around 15 MPH. This happens even during deliberately slow take-offs in a parking lot. I have the impression that if I turn the Power on but don’t put the car in Drive, let the engine run and shut down (see above) and then put the car in Drive and accelerate that the car will use the electric motor up to around 15 MPH.

This is a misimpression that Toyota propagated. It's better and more efficient to use the ICE for any acceleration to avoid the conversion losses to and from the battery.

[Skwyre7]

I agree with Evan.

[dwdean]

Originally Posted by efusco

Everything you described is normal...I'll give details below.

This is normal, esp. in cooler weather, esp. the first time it shuts down after a cold start.
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I confess this first one about "rough" ICE starts and stops is one that I've wondered about.

I live in Florida and I think the original poster is from North Carolina; not exactly cold climates, particularly at this time of year.

From my experience, this "rough" behavior is more common when the car is "cold", but I do see it sometimes after the engine should be quite warm. (At an ambient temperature in the 80 F range, I'm assuming that the engine is reaching operating temp in roughly five minutes. Therefore after having been running for 30 minutes or more, there's little chance of the engine being under optimum temperature.)

I haven't made the commitment to buying a ScanGauge yet, so I'm not sure what's really going on and am not sure that I'm $169 worth of curious.

If there's a simple way to capture data off the OBD port with a laptop, I'd try and capture one of these events, but I haven't seen anything...

I have noticed that these events have become much less frequent, as I've driven the car and ultimately chalked them up to a "new" engine. As nice as the rest of the car is, it would be good if Toyota could find a way to work this kink out. I bet they might save themselves some customer service inquires.....

[MichaelSF]

Wow... I belong to motorcycle and electronics forums. I know the amount of work it takes to respond to newbies.

Nice post efusco, and thanks for taking the time to answer those questions.

I don't have a Prius yet and even I learned something!

[N3FOL]

Symptoms looks normal to me too.

[tochatihu]

When our Dr. Fusco is not taking beans out of childrens' noses in the ER, he is very generous with his time and Prius-knowldege here. Three cheers.

Adding my low-value opinion that the original poster is not observing any unusual Prius behavior.

[onlynark]

at least the engine startup is not nearly as rough as it is in the HCHII. It always feels like a car rams me from behind.

[patsparks]

Hey Chuck, it's all good dude.
It's a great car but it has some funny quirks. After a while you won't even notice them.

[TonyPSchaefer]

Sometimes you'll feel a little give as you switch from regen to friction braking (when you hit a bump or when you get below 8mph)

I was actually thinking that CD666 was talking about the pump going off. I could see how this could be interpreted as "chatter".

Yes, the car will always go into S1. If it's nice and warm and the emissions controls are warm enough it will shut down again even before getting to S3 or S4

Doc is referring to the different stages of Prius operation. Basically, he's saying that the engine will always come on when you power up the car even if only for a brief while. This also addresses the "reverse" question; the engines running but the batteries propelling the car.

Otherwise, I fully agree with Evan. Enjoy your Prius and welcome to Priuschat!