Prius electric motor surging

There may be something wrong with the car. I have 105K miles on my 05 and have never noticed any type of surging.

 

+1

I have over 155,000 on the clock and never experienced a surging issue. I'm curious what the problem is.

 

Doesn't sound normal to me. I've had my 06 for a few weeks shy of 6 years now.

Try test driving another 2nd gen Prius, for comparison. Also, you didn't drive in B mode, did you? (Side note: Cruise control can't be engaged while in B.)

 

I have an 07 also and mine is smooth as can be.
You can see whats being used primarily if you look at the mfd consumption screen arrows.
But I think you may have a slight miss in the engine and your feeling that. Usually a very dirty throttle body can cause that. It can't be bad whatever it is or it would throw a cel. The car is real good about complaining when its unhappy.
Whats the mileage?

 

There are no settings to adjust.

This is a case where posting a youtube vid of the MFD + speedometer would be very helpful. Another issue: an electric motor is always engaged. It is only the gas engine that turns on/off.

In 4 cylinder cars with A/C compressor clutches, it is usually possible to discern the clutch engaging or disengaging. To me, that is how it feels when the Gen II gas engine turns on or turns off when the car is moving.

 

For me, it's obvious when the ICE turns on. The shutdown is obvious when stopped and usually is noticeable at very low speeds, esp. if it's a rough shutdown.

However, there are cases below 41 mph but above low speeds that it's impossible to tell by feel and sound that the ICE has shutdown. Only way to tell on those cases is by seeing ICE RPM drop to 0 on ScanGauge II.

 

I can't necessarily speak to the changes when using light steady pressure but the arrows going back and forth are totally normal if using cruise control.

I do use the MFD when trying to deadband while doing pulse and glide (http://www.cleanmpg.com/forums/showthread.php?t=1224). Once the ICE is warmed up, it should be possible to deadband w/o too much difficulty. You should be <41 mph.

How about you just ignore the display, switch it to something else or turn it off? Maybe it's all in your head or you are getting thrown off by the display.

 

It's completely normal for the MFD to display electric motor activity like that, but it's not normal for it to create any type of surging.

So the only two possibilities are:

1. You are imagining it. Looking at the display and seeing the arrows doing their dance is putting the idea into your head about the surging.

2. The Prius is faulty.

Try driving another Prius. If you don't notice the surge then option 2 above was the case, otherwise I'm afraid we have to go with option 1.

 

Yep... for option 1, that's why I suggest he turn off the MFD or switch it to something else.

 

Hi pfbloom. There is one specific anomaly in the Gen2 prius that can cause a very minor surge/retard type of thing, but it only happens if you're coasting or gliding at 41 - 42 MPH (specifically as your speed crosses above or below this 41 - 42 MPH threshold).

This happens because it wont do a true glide above 42 MPH, so it has to start the engine. The upshot is that if you're trying to glide or coast very close to 41 MPH then you sometimes notice a very slight feeling of pulsation as the engine is forced to start and stop each time the speed varies a bit above or below this threshold.

Given the speed and the energy monitor display you report however, this cant really explain your pulsations.

 

The Gen II Prius does produce a mild surging sensation when traveling straight and level down the highway. It is very slight; many people might not notice it. When I first got my 2006 I noticed it, as well as wandering at highway speeds. I don't notice anymore, as I have become accustomed to the idiosyncrasies of the Prius.

A pronounced surging is not normal. I recommend driving another Gen II and comparing.

Tom

 

Ok I guess I misunderstood your original post. I thought you were referring to a much more pronounced type of surging.

I suppose the control system that manages the distribution of power between the electric motors and engine is not exactly perfect. Next time I'm on a really smooth flat road I'll have to see if I can notice anything.

 

I get the same feeling in my 2010 from time to time. Happens at highway speeds or city speeds. Kind of feels like the transition between hybrid and elect functions only it only happens when the ice is running.

 

The only time I've noticed anything like this is with the cruise control activated. I feel the cruise control is pretty aggressive at maintaining the set speed, and will sometimes initiate more power demand than I would in order to do so. I haven't felt anything like that otherwise, though, aside from the very slight "bump" sensation when the gasoline engine starts and stops at speeds below 42 mph (or moving in and out of that threshold, as uart mentioned). I may have also felt a slight bump when one of the motor/generators reverses direction, but I'm not sure about that--just a hunch.

The Toyota and Honda hybrid systems are very different (let me give this a shot--others feel free to make corrections). Honda uses a series-hybrid configuration, which is more like a gasoline engine power train with supplemental electric drive assist and regenerative braking. Toyota uses a parallel-hybrid configuration, with the electric drive/regen and gasoline engine each holding up their own ends (of the power-split device), more like an electric car with gasoline engine assist. Each side has much more independence than in a series-hybrid system, and the parallel system is much more dependent on the electric drive than the series system. In the parallel-hybrid system, the only thing that "kicks in" and out is the gasoline engine (at speeds below 42 mph). At speeds above 42 mph, the gasoline engine must spin but there may or may not be fuel delivered to it. In the series-system, I believe the gasoline engine will not stop unless the car is stopped.

While traveling with fixed position of the go-pedal, the gasoline engine RPM and load and electric drive torque should stay pretty constant. This is not at all the case when trying to travel at fixed speed--then power demand and energy flow tend to shift pretty wildly.

You could try the old Jeepers' trick to maintain throttle position by digging the side of your go-pedal foot into the transmission tunnel. The travel of the go-pedal on these cars seems very light and it can be difficult to judge pedal pressure and position.

I agree that some insight could be gained by driving another Gen II.