Does anyone have surging issues?

[eclecticguy]

Folks,

I've been contemplating buying a new or used G2 Prius with up to 50K miles. I test drove an '04 with 36K miles a couple of days ago, and noticed a pronounced lean and surge problem out on the freeway after the car was warmed up. The car was a trade-in at a large Toyota agency in San Jose. After mentioning it to the salesman, he mentioned that it hadn't been serviced yet and might need some sort of transmission adjustment. First of all, isn't that low mileage to have such an issue surface?

I would have thought this to be an isolated case for this particular car, but while looking at some online reports today, I came across this statement from a Consumer Reports road test:

"There's a slight shudder as the gas engine cuts in or out, and the powertrain is prone to subtle but annoying surging and bogging in cruising conditions."

Have any of you experienced this driveability problem, and if so, was there an easy fix for it? I certainly don't want to lay down my hard-earned money for a car where I need to bring my barf bag on every trip! ;-)

Thx...

[IsrAmeriPrius]

The salesman is clueless. There is no direct correlation between the speed of the car and the engine RPM. The "transmission" is a fixed ratio planetary gear power splitting device. It allows the engine to run at the most efficient speed taking into consideration the power requirement and the battery charge.

That surge was the engine speeding up to supply the necessary power to maintain freeway speed and/or recharge the battery.

Take a look at the Toyota Prius - Power Split Device web page and make sure to drag the sliders to illustrate the power flow and the varying correlations of the RPMs of the internal combustion engine and the electric motors as the speed of the car changes.

[daniel]

Goes to show how ignorant most car salesmen are about the Prius. As IsrAmeriPrius says, there's nothing to adjust in the Prius "transmission" because there is no transmission. Just the power split device, which is essentially a differential.

The engine will change rpm as the computer decides more or less power is wanted, but I experience no surging in the car itself, except the powerful way it surges forward when I step on the accelerator.

[eclecticguy]

<div class='quotetop'>QUOTE(IsrAmeriPrius @ Nov 28 2007, 12:18 AM) [snapback]545075[/snapback]</div>

That surge was the engine speeding up to supply the necessary power to maintain freeway speed and/or recharge the battery.
[/b]

Thanks for your response. Keep in mind, though, that this wasn't a momentary surge. It was a constant gentle bucking the entire way at highway speeds.

[qbee42]

<div class='quotetop'>QUOTE(Eclectic_Guy @ Nov 28 2007, 01:28 AM) [snapback]545104[/snapback]</div>

Thanks for your response. Keep in mind, though, that this wasn't a momentary surge. It was a constant gentle bucking the entire way at highway speeds.
[/b]

Still, the salesman was clueless. As the others have said, there is nothing to adjust relating to the transmission. The Prius does have a little different feel than many ordinary cars. What you are describing could be normal, but there is no way to tell without feeling it. Try driving another Prius, or have a Prius owner drive this car.

As for the engine shut down, it is normal to feel a bit of a shudder. Think about how much fuss a normal car makes starting and shutting down. The Prius is actually quite smooth.

Tom

[Bill Lumbergh]

I've felt a light surging on three occasions, all of which occurred when it was -20 F outside or colder. All three times it lasted the duration of my trip to work (about 15 minutes), and only when travelling at a constant speed was it noticeable.

There may be an issue that needs to be addressed with that car's MAF.

[a priori]

Do the surging and engine shudder really just relate to the temperature of the engine? I've never driven a Prius in temps below 25F (this will be my first winter with my Prius), but I do know that the shut-down shudder of the engine is very noticeable only when the engine is still quite cold (even in 90F weather). After warm-up, the shut-down is nearly imperceptible, except to the driver, I suppose.

I've never experienced what has been desribed here as surging. Should I expect to have this happen as the temps drop? It seems to me that this surging is a non-normal event that requires attention.

[Ichabod]

I can't really speak for any Prius but my own, but I never feel "surging" that I don't expect, i.e. from something other than stepping on or releasing the gas pedal. It's possible that what you felt was normal, especially if you were at around 42 MPH when driving, because the ICE can more frequently cut in and out if you're drifting above and below that speed. Far from annoying, that's one of the most useful things about learning how to maximize MPG in a Prius... But that might not have been the issue you experienced.

I'll second the suggestion to test drive another Prius in similar conditions, or to have a Prius owner test drive the car in question. Salesmen and even techs might not know what's "normal" in terms of the driving experience.

[edit]
On reflection, I'm thinking driving style might contribute to what you felt. If you drive with a heavy foot, and do frequent accel/decel on the highway (or were doing such on your test drive to "test the limits" of the car), then you might be working against the HSD: steady demand for power is usually handled nicely, and a gentle press on the accelerator will speed you up, but not with a burst of power. If you mash the gas pedal, you'll get that burst of power though, at the expense of higher ICE RPM. You may feel like the car surges a little, or is slow to give you the power you demanded.

[another edit]
It also just occurred to me that maybe all of us Prius owners have been hypnotized by a barely noticeable surging. That might explain why we all seem to speak so glowingly of our cars: The "Brainwashing Hypnosis Inducing Surge" feature that was listed way down at the bottom of the features list.

[David Beale]

My car will "surge" slightly, though I haven't noticed it on the highway. It will repeatedly do it in the city once in a while, usually at lights when stopped, as the system tries to decide if it wants the engine running. Very gentle "nudge". I only started noticing it when I became used to the car and sensitive to what it is doing (because I'm curious). It's not a safety issue, nor would it cause motion sickness, at least in my car.

As stated above, there are no "transmission adjustments" that can be done. They -can- change the transmission fluid. I suppose it's possible the fluid (oil) could cause it to run a little rougher (stiffer).

It's also possible, as mentioned above, that there is an out of spec. sensor on the engine. If the engine surges the car will do the same on the highway. Sometimes this will throw a code, sometimes it won't.

[daniel]

Constant bucking on the highway while your foot is applying constant, unchanging pressure on the accelerator, is not normal. There is something wrong with the car if that's the case.

There is sometimes a slight shudder as the engine stops and starts. More common and more noticeable before the car is fully warmed up.