Strange engine behaviour -- like revving while stopped at light

they could be right, but it is not so far out of balance to throw a code yet.

have you checked the 12v health? how old is it?

 

I've noticed odd rev up directly after a 12 volt battery disconnect, during warm up, say within the first minute or two of start up. And this is for just the first one or two startups. I get the sense mine was some sorta recalibration.

In your case, might be similar process, with different trigger?

 

Have you ever changed the transmission fluid?

Are there any periods during acceleration at highway speeds that you notice hesitation?

Do you ever have issues with cold start knock at the beginning of the day?

Ever clean or check the hybrid fan?

 

My 2010, 2005 and 2004 Prius’s have all done the same thing when they get a bit of mileage on them (150,000 plus)
On the 2010 I have changed the trans oil, inverter coolant, cleaned the egr cooler and none of this has stopped this behaviour, I have now concluded that it’s something that happens on higher mileage cars with full batteries


2010 Gen 3

 

Had the same high rev when stopped. Sent in for hybrid battery change.

 

This almost sounds like and EGR issue but you would probably be experiencing misfires and possible DTC.

 

when the battery is full the engine may rev to burn off excess electrons.

 

I have read this somewhere else as well


2010 Gen 3

 

The computer is revving the ICE to "burn off" excess battery charge. The electrics are spinning the gas motor, but no gas is being burned. It is simply protecting the HV battery from over-charging...happened all the time in our Gen 2. An older NiMH Traction Battery loses efficiency as it ages, i.e., can't store as much energy, discharges sooner and charges faster than when new. The car still regenerates as much energy as always since it still weighs the same, but the battery cannot store as much as before. Thus, the computer has to "burn off" this excess energy.

 

Sign of failing battery then?

 

More like a degraded battery. It is still functioning, just not as efficiently as when new. You may notice lower MPG, but you are still able to drive normally. Failing batteries are indicated by transient warning lights (triangles/exclamation points) and messages (Hybrid System Failure), and inability to enter Ready mode.

 

^ I read that as "Car Has Too MUCH Power!" and that put a smile on my face.

 

I agree with Mendel and FuelMiser. Driving on SF hills, had 8 bars (75% SOC on techstream) for 5 straight minutes and still driving downhill then came to full traffic stop. Engine has yet rev'd up.

 

They can do a hybrid health check with techstream I think? If you google that with Toyota at the beginning you'll find some info.

 

Have you ever cleaned the MAF air flow sensor and I bet your throttle body is really dirty. A dirty throttle body will cause a high idle, cheap to clean. It may have never been cleaned.

 

I’m thinking the same thing. The throttle plate may be slightly cracked open due to sludge and carbon build-up. If that’s the case, the throttle position sensor can send erroneous date back to the ECM and cause a high idle. As “padroo” suggests, it might be time to thourghly clean the TB.