Brand New 4Runner engine shakes when i shut it off

Hello,

This is my first post on this forum, I got my 2023 4Runner a month ago and has about 1700km only.
I noticed after i shut off the vehicle the engine has a slight vibration right after shut off . It's not really noticeable unless you really pay close attention to it .Is this normal? Does your Runner do this?

 

My ORP is 2 months old. It does NOT do that. Page 8 of Owner’s Manual does describe noise coming from under vehicle 5 hours after shut-off, but not immediately.

"Approximately five hours after the engine is turned off, you may hear sound
coming from under the vehicle for several minutes. This is the sound of a fuel
evaporation leakage check, and it does not indicate a malfunction."

 

No shake from the engine upon shut off, But I have noticed the noise mentioned above and it emanates from the rear of the vehicle and is a slight hum. Typically happens after 4-5 hours on shut down however.

 

That hum noise you hear is the fuel pump. Damn near drove me crazy because we would be in the garage and hear that. I took it to the dealership and its the fuel pump and is completely normal

 

On mine the humming noise was verified as being from the evaporative system pressure test that the system performs.

 

Maybe I should have said a slight shrudder vibration right after I turn off the engine. It’s not a obvious noticeable shake . Sorry maybe I wasn’t clear On describing.

 

Engine tremble or shudder at shut down can be detonation, I'd take it back to dealer for service. Friend had a similar problem from a un-torqued spark plug.

 

Welcome. It may be something and it may be nothing.

First question is, what are you comparing the shutter to? It sounds like it’s so faint that you have to really look for it.

Second question, do you have any DTC codes or check engine light?

Third question, have you tried a different gas station or higher octane fuel? Some people think it’s ok to run 85 octane at sea level and it will definitely cause issues if that’s the case. Also, you can generally narrow down a detonation issue that is cause by fuel, with a higher octane.

If the above doesn’t help, I’d take it to the dealer for service.

 

It's hard to say for sure if I know what you mean. Sometimes mine shuts down with a tiny shudder, just bit of vibration. It's not much different than the shut-down on other truck engines I've experienced.

 

Video would help.

 

Yes, its very faint to really notice it if you are not paying attention to it. I have had it for a month and never even noticed it until this morning when i reached my work parking lot thats when i pressed the off button i notice a very slight faint vibration for about one second right after engine shut off.

 

Maybe i should try a higher octane gas and see and No there are no check engine light on my dash.

 

Depends on what you mean by shake. These aren’t smooth engine at any point.

 

Is it maybe the engine making it’s last bit of rotation after ignition is cut? They don’t stop precisely when the ignition is cut due to rotational mass/inertia. But it’s a very short period of time, maybe less or more depending on piston positions. In any case, it would be much less than a full second.

 

def doesn’t hurt to try a different octane. as unlikely as it may be it the easiest possibility to eliminate.

 

High octane gas isn't going to do anything for these engines. This is not a performance engine that would require the characteristics of what high octane fuel brings to the table. I would suggest some light reading on what the differences of the octanes are and what/when they are used.

 

I think what you are experiencing is normal. I have a 2023 Limited and I can feel a slight shudder both when I start the engine and when I shut it off. The Tacoma TRD Sport with the 1GR-FE engine that I drove for over 12 years before the 4Runner did the same thing. Have someone start the engine while you have the hood open - you'll see the engine shake a little both starting and shutting down. Upon starting there is a rotational mass that goes from stationary to moving very fast in a fraction of a second - on shut down the same rotational mass goes from moving pretty fast to stationary in a fraction of a second. Your going to feel the engine start and shutoff - simple mechanical dynamics. Also, the 4Runner's suspension is not intended to be a "luxury" ride. These are body on frame trucks and they ride as such. So you will feel engine start/stop shudder more on a vehicle like a 4Runner than on SUVs that are designed to ride softer.

 

My '22 doesn't. But I do hear and feel the secondary air pump run momentarily after shut off. It's to clear water in it. Could that be what you're feeling?

 

OK - everyone who is saying their 4Runner doesn't do this - I don't think you are understanding exactly what the OP is describing - or I'm not. When you start the engine the moving/rotational mass within the engine (pistons, crankshaft, etc...) goes from stationary to about 1500-1600 RPMs in less than a second. The acceleration/deceleration of the mass of the moving parts of the engine required to go from zero to 1500 rpms at startup, or 1100 rpms to zero on shutdown causes the engine to slightly shudder - every 4Runner does this at startup and shutoff - and you can feel it. Hell, you can even see it. It lasts less than a second - once the engine starts/stops their is no further vibration/shudder. In fact, I just went out and started my 2023 Limited and the slight shudder, that lasts less than a second when the engine shuts off, was over before the secondary air pump made the sound it makes when it purges. It is completely normal - and every ICE vehicle does this to some degree.

 

Yeah, conservation of angular momentum is an actual thing.

 

Agreed, all of my cars have done this.

 

Still no video OP?

 

Can you give us a graph on all this rotational mass acceleration/deceleration stuff?

 

Man I would take it to the dealer for sure to start a record of issue with it.