Rattle on downshift ?

Hi folks,

I know the 3.5 is a noisy engine, but searched and couldn’t find this. ‘18 3.5, AT, 4x4, 31k miles. Factory oil weight and noticed for at least the last 5k miles or so.

When doing a downshift under a little load and at low RPMs (say the truck is in 4th with even throttle, then starts going uphill, rpms drop, and truck shifts to 3rd) there is a rattle that lasts a couple seconds. Sounds almost like a lifter or something in the valvetrain.

We used to have an old 3.5 RAV4 and I can vaguely remember the same thing - is this ‘Toyota normal’, or should I have it looked at by the stealership?

Thanks a ton!

 

aaaanyone?

 

Check your exaust system for broken weld point for heat shield (tin foil stomped panel on the top of cats or mufflers). Usually they point welded to exaust components. You find loose one? Weld it back or use stainless steel clamp, or zync coated tie-wire t tie it up.
Done.
DO NOT RIP HEAT SHIELDS OFF! They there for reason, they keeping thermal corrosion points from starting!

 

Thanks! This definitely sounds like an engine related rattle to me, but I will poke around.

 

Hate to drag up an older post, but did you ever figure this rattle out? My 21 us doing the same, and getting worse...

 

Probably spark knock.

 

Try switching to 91 octane on next fill up.

 

I'll try it. Sounds kinda like a fuel knock, but it's pretty violent sounding, and only for 1 second or less during a down shift with light throttle.
And only sometimes, usually doesn't do it.

 

Well, I'm a 1/2 tank of 91 in, and haven't heard the rattle yet....
Hard for me to believe that was a spark knock I was hearing, only during very light throttle with a downshift, but apparently it was.
And I'm an ASE master tech. BUT, I work on diesels only lol.

 

Nope, never found anything out. I’ve stopped noticing it - I think it’s not an issue for me at least.

 

My 2020 does the same. Always under light acceleration when going up a hill and the trans decides to downshift from 6th to 5th or 5th to 4th. I started noticing it about a year ago and couldn’t figure it out myself. If it’s spark knock, any chance the dealer could address this?

 

I would think an update to the shifting would eliminate much of it. That's really my only complaint with this truck. The shifting is maddening, to the point I'm constantly thinking about it.
I've heard of tunes to address it, I think I'll look into it soon.
As far as my rattle, it completely went away with 91 octane, put 87 back in it and it came back, but not nearly as bad as before.
Now that I know what it is, I'll deal with it as long as 91 is pushing 5 bucks a gallon.
I'm a little surprised this isn't more widely discussed. Would be nice if Toyota had a reprogram TSB for this like they did with my 2010 goofy shifting problem.

 

It has been brought up on here a few times. It's enough that Toyota even mentions it in the manual, and says it's normal.

 

ktbell444, Where in the manual does it say this? I've been trying to find something. Do you by chance have access to the above mentioned conversations about this issue? I'd love to read more about other people's experiences! Thank you in advance!



I have a '23 with 7,000 miles, original oil - only a tire rotation so far. I am also noticing this sound upon shifting (I believe up or down) while going up a hill under power, and only for a brief split second. This is definitely not the direct injection tapping noise that can be heard at idle. Its happening pretty normally, but varies in intensity, and can't make it happen on command/replicate except under very specific circumstances. Windows really need to be down to hear it, and preferably passing a wall, guardrail or something that the sound of the truck can bounce off of.

Here is a video of the kind of sound I am hearing, but in an older Ford. Fast-forward to 2:45: https://www.youtube.com/watch?v=JA0cH_vRABg
The sound coming from the car in the video is much worse and longer lasting, but this is it.

So far, I have read that it may be a detonation/valve thing (which is exactly what it sounds like). From what I have read, other taco owners have had success resetting learned truck behaviors back to factory by removing and reinstalling EFI fuse, and using higher octane gas.

I have a long trip up and down mountains to Joshua Tree tomorrow. Will relay outcome afterwards.

(Baffled that Octane would be an issue in a vehicle tuned for 87 from the 2020s and that should have instant computerized timing!)

 

Yup, this is exactly how I'd describe what I'm experiencing. Almost a year later, I feel like it's gotten mildly worse. If I give the throttle a quick jolt of acceleration on level ground without letting it downshift, I can get even more violent knocks. Been using Top Tier fuel 87 octane only, tried 93 a couple times and that seemingly made it go away (but I'm too cheap to fill 93 every time ) surprised that it hasn't improved otherwise. I'm considering changing the spark plugs now that I'm at 50k hoping that it would help, and going to do an oil analysis when I change my oil in a week or two just to double check I'm not seeing any extra wear.

Attached the page in the manual that mentions it.