engine flapping sound

Sad to say but it is normal, especially if you start the car to move it a short distance (driveway to garage for example), turn it off before the engine completes it's warmup cycle and then let it cold-soak over night.

The two typical workarounds are to always let the engine complete it's warmup cycle, or once it is knocking on startup floor the accelerator.

 

there is no need to let your ice start for a short time such as moving around yard, unless you let it run all the way down. in that situation, i always make sure i'm within charging range before starting.

 

I think the sound (s)he's hearing is that of the electric vacuum brake canister recharging - which is normal regardless of the battery's SOC .

 

why would they only hear it when the ice fires?

 

do not know . . . I seem to here the one on our hybrid Lexus most frequently when any of the doors are 1st opened in the morning.

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that's when i get it to, that buzzing sound. only my drivers door does it.

 

Although it's not the situation the OP described, I am grateful for this information. Now, I know what this buzz after I open driver's door is.

 

that's funny, i thought everyone knew the latest buzz.

 

I hear this "flapping" sound every day when I manually switch over to HV mode while pulling onto an on-ramp. (already traveling at some speed) If I am stopped at a stoplight and make the change, I don't hear the sound. It seems to me that it is related to vehicle/drivetrain speed and load when the ICE is activated.

 

i would make the switch a few minutes before the ramp.

 

Meh... It doesn't really bother me, just adding a point of reference.

 

It was 10 below zero yesterday morning. I moved the car out of the garage to make room for some wiring for a portable generator installation. Later in the day, I started it up to put it back in the garage and it sounded like a freaking cat was flopping around under the hood. It sounded like hell. I've heard it once before several months ago but it only lasted 2-3 seconds, immediately after starting the car. I've been worried since yesterday's experience, wondering if it would make it to the dealer, or if I should even take it in to have the dealer look at it. ???

 

no, don't bother, it's a known issue with no fix. but here's the good part, you can move it around in ev, unlike our lift back brothers, so you can choose to avoid the situation.

 

"it's a known issue with no fix..."

Does it cause any permanent damage to the engine or motor mounts? If so, that would bode for Toyota covering repairs in the future (even after warranty) due to this apparent design flaw. Unless anyone has reported either engine or motor mount failures, it's more an irritation than a problem.