Question regarding 2021 Yaris

[amron]

I've seen a post on Israeli page of Yaris on facebook about people who own the 2021 Yaris. they complain that since Toyota have changed the engines on these models from the 4 cylinder version to a new 3 cylinder version, the vehicles suffers from vibrations on low rpm, for example, when waiting at a traffic light. they where told by Toyota authorized workshops that it's normal for that engine, something that I find very odd that Toyota will market a vehicle with this "phenomena". have anyone  heard about it?

[FROSTYBALLS]

Are you asking about the petrol or hybrid version? Toyota Owners Club is UK based, and the UK only has the hybrid version.

[TonyHSD]

All 3 cylinders engines has vibrations and typical noise like hairdryer but once you get use to you kind of like it and easy to live with. Hybrid at least most of the time while waiting on traffic lights the ice will be off therefore not a big issue with vibrations and although I have not tried yet any these cars I am sure that they are not that bad or worse than any other 3 cylinder engines., they sound to me exactly like Mitsubishi colt from 2006-2013 and I had over 20 of these. 👌

[Mikw]

My last three cars have had 3 cylinder engines. Never had any problems with them. You soon forget the lack of a 4th cylinder when you're driving them. And when stationary, or at low revs, Yaris Hybrid is almost always on electric power and with the engine off anyway.

Bear in mind that, despite the loss of a cylinder, the 4th generation Yaris is more economical the previous one by some distance.

[amron]

Thanx for your comments. I forgot to mention that my question reffered to the petrol version, not the hybrid.

[Stopeter44]

Currently driving a 3 cylinder car, not a Toyota. To tell the truth I have always liked the sound, compared with a 4 cyl. I think @TonyHSD has it right when he says :-

13 hours ago, TonyHSD said:

All 3 cylinders engines has vibrations and typical noise like hairdryer but once you get use to you kind of like it and easy to live with. 

Although, I might have said more like an old fashioned electric sewing machine. The Toyota 3 cyl. has 120° stroke differences, so I guess it might be a bit thrummy.

Dynamic Force 1.5 Toyota video

[flash22]

A 3 cylinder, by its nature is unbalanced so prone to a bit more vibration with a firing order of 1,3,2 whereas a 4 cylinder has a companion cylinder with a typical firing order of 1, 3, 4, 2 so the rotating mass is more balanced

you can cut the vibrations of a 3-cylinder engine by using a balance shaft, but this adds to the cost, weight and makes an engine more complex, but a 3 cylinder will always sound and feel different

[Stopeter44]

46 minutes ago, flash22 said:

You can cut the vibrations of a 3-cylinder engine by using a balance shaft, but this adds to the cost, weight and makes an engine more complex, but a 3 cylinder will always sound and feel different

Yes, but most of today's Automakers use 3 cyl. in their segment A/B models. I drove a 108, same engine as the Aygo, a while back and it's definitely more thrum than the 3 in my current 208. I had assumed that the balance shaft was de rigeur, but I from what you say it is not always the case. The short video from Toyota looks like it shows a balance shaft. Does the Dynamic Force 1.5 have one ?

Edited October 31, 2021 by Stopeter44
Needed to change a sentence

[flash22]

IIRC the 1KR uses balance weights on the crank, 208 uses the PSA EB engine that has a balance shaft

[TonyHSD]

44 minutes ago, Stopeter44 said:

Yes, but most of today's Automakers use 3 cyl. in their segment A/B models. I drove a 108, same engine as the Aygo, a while back and it's definitely more thrum than the 3 in my current 208. I had assumed that the balance shaft was de rigeur, but I from what you say it is not always the case. The short video from Toyota looks like it shows a balance shaft. Does the Dynamic Force 1.5 have one ?

Good video, thanks. It seems it does but I think most cars has a balance shaft these days. Some are driven by belts , chains or like here with Toyota 1.5 by gears., which is the best imo. 👍

[Stopeter44]

@TonyHSD Yes, the video is short and sweet, and it looks like you and @flash22 are both right. I don't know exactly how a balance shaft works, but I thought it was a shaft with weights arranged in such a way to offset the uneven vibrations of the 3 cyl.

However, as you indicate with the red arrow there's a shaft, that looks like it's driven by the flywheel, directly under the crankshaft. That shaft has a disk with an off centred mass on it. During the video you can see it coming in and out of view.

[flash22]

The balance shaft is driven directly from the crank at the front of the engine (click to enlarge the picture)

https://toyota-club.net/files/faq/20-08-01_faq_df_r3_en.htm

[Cyker]

The 3-pot in my Mk4 is surprisingly smooth for a 3-pot most of the time - I find most 3-pots actually feel smoother the faster they rev; It's at idle where they're most obnoxious.

The one time it definitely isn't smooth in my Mk4 is when the car is using the engine to charge the Battery while stationary, e.g. when the Battery drops to 3 bars and the car is in P, or stopped for ages in traffic.

For some reason, in that situation, the engine is extremely noisy and has a lot of vibration, and you can feel the whole car ***** very slightly when it switches into that mode. But it *only* does it in that situation! If the car is moving, even slightly, like 0.5mph, it's as smooth as anything, even if the engine is still running at 2000rpm to charge the Battery. It's really weird...

Edit: ***** is not a swear word! judder? shudder? hitch? flinch?

[TonyHSD]

27 minutes ago, Cyker said:

The 3-pot in my Mk4 is surprisingly smooth for a 3-pot most of the time - I find most 3-pots actually feel smoother the faster they rev; It's at idle where they're most obnoxious.

The one time it definitely isn't smooth in my Mk4 is when the car is using the engine to charge the battery while stationary, e.g. when the battery drops to 3 bars and the car is in P, or stopped for ages in traffic.

For some reason, in that situation, the engine is extremely noisy and has a lot of vibration, and you can feel the whole car ***** very slightly when it switches into that mode. But it *only* does it in that situation! If the car is moving, even slightly, like 0.5mph, it's as smooth as anything, even if the engine is still running at 2000rpm to charge the battery. It's really weird...

Edit: ***** is not a swear word! judder? shudder? hitch? flinch?

This also happens to all Toyota hybrids like Prius and others with 4 cylinder engines. I think the engine has extra load to recharge the Battery but the same time is running in different cycle(timing adjusted or switch between Atkinson and Otto) to save on fuel since it’s not driving the car and just need to turn the generator. This is also the time when in older gen 3 hybrids when you have a blocked egr you get bad knock from the clutch dampener. How interesting machines are these cars 👌😉

[Stopeter44]

5 hours ago, flash22 said:

The balance shaft is driven directly from the crank at the front of the engine (click to enlarge the picture)

https://toyota-club.net/files/faq/20-08-01_faq_df_r3_en.htm

I read all the way to the end of that article, very interesting. I have to admit I do not know enough about ICE to take it all in, and certainly not on one read. It does look like the DNF 1.5 used as a standalone ICE has a balance shaft, and when used in association with MG1/MG2 in a hybrid does not have a balance shaft. I also learned some stuff about Miller vs Atkinson.

[Cyker]

Ahh thanks Tony - I hadn't noticed it so obviously in the Corolla hybrid my uncle tested, and assumed it was just because of the 3-pot vs 4-pot thing, so that's good to know!

re. the toyota-club.net article - According to the Toyota engineers the hybrid M15A-FXE engine *does* have a balancer, but apparently it's part of MG1 and not a separate shaft like in the non-hybrid -FKS, if I understand correctly!

https://youtu.be/VgD-tHycnPQ?t=145

 

[TonyHSD]

Yes, it seems like Yaris hybrid has only port injection and no balance shaft, the balance only comes from the wheel (pulley) that usually turns the aux belt. 👌 Thanks for sharing that info, love articles like that one👍

[flash22]

A bit of brain fog yesterday, the hybrid doesn't need the balance shaft due to the way the hybrid system works with the 3 way power transfer

[CPN]

On 10/31/2021 at 6:14 PM, Stopeter44 said:

I read all the way to the end of that article, very interesting. I have to admit I do not know enough about ICE to take it all in, and certainly not on one read. It does look like the DNF 1.5 used as a standalone ICE has a balance shaft, and when used in association with MG1/MG2 in a hybrid does not have a balance shaft. I also learned some stuff about Miller vs Atkinson.

As I understand it, the ICE in the Mk4 (NGA platform) is Otto/Atkinson and not Miller/Atkinson? (Miller is a U.S. patent anyway and I don't think that many outside the States make use of it BIMBW...)

[Cyker]

It's more (Atkinson/Miller)/Otto cycle  

Atkinson and Miller can be used interchangeably when talking about hybrids - It's just splitting hairs basically. For the purposes of the Toyota system, they represent the same thing/idea. (i.e. differing compression and expansion ratios)

Atkinson is the 'original' idea, having physically different compression and expansion strokes/ratios, and used a complicated linkage to make the compression stroke move less and the expansion stroke move a lot more. It's interesting to watch in action, but you can quickly see why it wouldn't have worked in the real world - It's too complicated and fragile to stay reliable over the long term.

Later, Miller came along and thought to use a long diesel-like stroke combined with delayed/early valve timings to simulate the same thing, so the cylinders in his system moved the same amount, unlike Atkinson's. Instead of the complicated linkage, he just had the intake valve close late, allowing some of the intake charge to be pushed back out and effectively reducing the ratio of the long compression stroke, since it only actually starts compressing from half-way up the cylinder. During the expansion stroke, the piston moves the full length, extracting much more energy than a shorter Otto-length stroke would, which is where the higher efficiency comes from. His system worked well, but because of the smaller intake charge (Since half of it was pushed back out again), it lacked power and was comparatively gutless, so he paired it with a supercharger to make it more usable in the real world.

The schism comes because pedants like myself want to call the Toyota system the Miller cycle, as it's literally the Miller cycle without a supercharger, but for whatever reason Toyota have always called it the Atkinson cycle, so there's a bit of to-and-fro, but it's mostly trivial as they both convey the same idea. Also Miller is shorter to write

 

[Stopeter44]

25 minutes ago, Cyker said:

It's more (Atkinson/Miller)/Otto cycle  

Atkinson and Miller can be used interchangeably when talking about hybrids - It's just splitting hairs basically. For the purposes of the Toyota system, they represent the same thing/idea. (i.e. differing compression and expansion ratios)

<snip>

The schism comes because pedants like myself want to call the Toyota system the Miller cycle, as it's literally the Miller cycle without a supercharger, but for whatever reason Toyota have always called it the Atkinson cycle, so there's a bit of to-and-fro, but it's mostly trivial as they both convey the same idea. Also Miller is shorter to write

 

Nice summary of the difference between Atkinson & Miller. It might be that Toyota call it 'Atkinson' for patent reasons, and therefore licensing rights, although I thought patents lapsed after 20 years ?

[CPN]

3 hours ago, Cyker said:

The schism comes because pedants like myself want to call the Toyota system the Miller cycle, as it's literally the Miller cycle without a supercharger, but for whatever reason Toyota have always called it the Atkinson cycle, so there's a bit of to-and-fro, but it's mostly trivial as they both convey the same idea. Also Miller is shorter to write

Lol! That lack of a supercharger factor is why I didn't think it was correct to call the Toyota ICEs "Miller" instead of Atkinson... (and I think that's why Toyota prefer Atkinson also...)

[Cyker]

That is true! The opposing argument is that the Toyota system doesn't use the crazy complicated linkage to make the cylinder move a bit on the compression stroke and a lot on the expansion stroke - Really neither term is strictly correct!

I feel they missed a trick - They should have called it the Toyota Super Efficiency cycle or something  

 

[RickyC]

The original Atkinson idea is too huge and complex to be really used on a car.  I don't expect to find a car with a real Atkinson engine.  All car engines labelled as Atkinson are really using a Miller cycle. 

As far as I know Miller was a Ford engineer so probably the "Miller cycle" definition can't be easiy used without agreement.  And Toyota and Ford are no more working together.

The real Atkinson cycle could be used on big ship engines or fixed electric power generators.