Yaris mk4 engine noises.

[Nixy]

Hi. Why is it that I get two different noises, milder and harsher, when the Battery is recharged? The louder noise is quit a bit annoying when it cuts in, suddenly. Thanks. 

[TonyHSD]

Hi, 

toyota hybrids are like that and interesting machine indeed with many different noises and behaviour in comparison with standard petrol cars. The engine can run in Atkinson or Otto cycles depending on what else needs to do while charging the Battery and perhaps this is the reason why you can hear changes the sound and rpm. Also depends if the Battery is empty, coolant temperature, and if the car is stationary or in motion. 👍

[Cyker]

I know right?? It's one of the weird things I've been whinging about on and off since I got my Mk4. It's not a big problem, just irritating as the rest of the time the car is so much smoother and quieter.

It seems specifically to be a thing with the Mk4 Yaris, and I suspect in no small part because of the 3 cylinder engine, because it's far less obnoxious in the Corolla and earlier hybrids (Which are pretty much all 4 or more cylinder)

I still don't know for sure why it only gets noisy when the car is stationary, and quietens down as soon as you start moving, even at like 2mph.

My only theory so far is it's something to do with the fact that the M15A-FXE doesn't have any balancer shafts, but has counterweights on MG1 instead. Why that would cause this I don't know... but the FKS engine doesn't have this issue even at idle and DOES have balancer shafts (I kinda has to since it's running all the time!)

[Nixy]

Thanks for the quick response. I have asked the chief mechanic of my dealership and he has no answer. Surely Toyota must have an explanation. Again it is weird than none of the car testers I have read before buying the car, ever mentioned it! 

[Cyker]

It only does it if you're stopped for so long the Battery level drops to 3 bars (or drained it to 3 bars on EV-only movement then stopped) so the car wants to charge while you're not moving

I wish I could tweak the levels so it wouldn't charge while stationary unless the level dropped to 2 bars, but would run the engine while moving at 3 bars or less. That would fix the problem...

Either that or bring the target charge from 4 bars to 5 bars so it has 2 bars to drop before is wants to charge the Battery...

Unless your dealer mechanic is a contentious sort they probably know less about the nitty gritty details of the car than we do so don't hold your breath on getting a factual answer...

Hmm I think I may have e-mailed this question to toyota customer services but don't think I got a reply either.

[Bernard Foy]

I think Cyker and Tony HSD have given as good an answer as you’re gonna get. Mine is the same, and I have to get used to it and it’s only for a brief period. Given all the excellent characteristics of the Mark4 Yaris Hybrid I willingly turn a deaf ear.

[Nixy]

I will pursue it with vigour and report back, if and when I have answers. This awful noise is startling and annoying. On another note I find the dash make a few noises, probably due to the hard plastics everywhere. Also I think the acceleration is down noticeably from when new. Don't know how to check it. 

[Cyker]

I was just curious about the cause but it's 'normal' and not considered a problem. My solution is just to drive faster and take ridiculous detours to avoid long queues of traffic  

But I really enjoy driving mine so any excuse...  

 

[flash22]

It's the hybrid way of life, when the engine starts to charge the engine idles up, the brake booster is electric, and at time you get strange fan and pump sounds - the ecvt sounds like a hive full of hornets under acceleration

the 3 pot engine has its own quirks

[Cyker]

This is different, it's specific to the Mk4 as I've not experienced it in any other Toyota hybrid so far.

Like, if the car is charging and you're moving, it's quite smooth and not that loud, but as you stop it suddenly gets much louder and the vibrations increase a lot - It's what I'd imagine would happen if it had a balancer shaft that suddenly disengaged which is why I suspect it's something to do with how MG1 interacts with the engine between when the car is moving and stationary.

It's not a major issue at all, just a gripe - It's just very stark as the car is normally much quieter, and it doesn't happen all that often, so you forget and then it happens and it's annoying.

 

[TonyHSD]

I was driving previously small cars with 3 cylinder engine and they sounded exactly the same as mk4. Now I have a couple of neighbours that own MK4’s and every time they drive pass my house I can hear them going up the hill. The funny thing is that they sound like two cars going together, one Aygo and one Prius 😀👌

[TonyHSD]

Just now, Cyker said:

This is different, it's specific to the Mk4 as I've not experienced it in any other Toyota hybrid so far.

Like, if the car is charging and you're moving, it's quite smooth and not that loud, but as you stop it suddenly gets much louder and the vibrations increase a lot - It's what I'd imagine would happen if it had a balancer shaft that suddenly disengaged which is why I suspect it's something to do with how MG1 interacts with the engine between when the car is moving and stationary.

It's not a major issue at all, just a gripe - It's just very stark as the car is normally much quieter, and it doesn't happen all that often, so you forget and then it happens and it's annoying.

 

My Auris is exactly the same. If Battery is empty and you are parked in P the engine is louder than usual and you can feel vibrations on the floor, pedal, seat, and everywhere. I can imagine the 3 cylinder engine with character voice adding to the overall experience. 🎺🎼🎷

[Nixy]

Lastly, when I begin to drive, with the Battery almost full, the engine will still cut in, in no more than 15 to 30 seconds after. 

[TonyHSD]

5 minutes ago, Nixy said:

Lastly, when I begin to drive, with the battery almost full, the engine will still cut in, in no more than 15 to 30 seconds after. 

That’s normal too. Engine need to reach certain temperature level to be ready safely to operate. It’s a parallel hybrid system that works simultaneously most of the time and occasionally on one power supply only. It is not designed to work only on petrol or on Battery power alone. Also when Battery is fully charged the engine may start to spin to discharge the Battery to more appropriate levels, the car likes to keep battery state of charge between 42 and 78% 👍

[CPN]

I've seen my Mk4 regularly go down to as low as 32% SoC before it will bring the ICE to life and start recharging... I'm pretty sure the Mk4's lithium-ion pack has a wider conditioning margin that the older NiMH in the Mk3...

[Nixy]

Hi. I think I am satisfied with all the information received as to the source and nature of the engine noises. Nevertheless it is an unpleasant experience. Especially when at the traffic lights noiseless and all of a sudden all hell breaks loose. 

[fourbanks]

19 hours ago, Nixy said:

Thanks for the quick response. I have asked the chief mechanic of my dealership and he has no answer. Surely Toyota must have an explanation. Again it is weird than none of the car testers I have read before buying the car, ever mentioned it! 

Most dealers i know in my 50 years of driving know nothing. I've yet to come across a mechanic who understands cars other than the basics, and in reality this type of forum is far better to understand what goes on with the vast majority of troubleshooting 

[flash22]

Most dealers are parts fitters, they either don't put staff on the training programs or they don't compensate the staff with knowledge, so they find somewhere that does - it's cheaper to pay minimum wage to someone fresh out of college to change oil than it is to let a qualified experienced tech do it

 

The technical and electronic side of things is an area that's lacking, and it's only going to get worse, a computer can only tell you so much and this is only as good as the person who wrote the information

[baxuz]

22 hours ago, TonyHSD said:

. The engine can run in Atkinson or Otto cycles depending on what else needs to do while charging the battery and perhaps this is the reason why you can hear changes the sound and rpm.

Really?

Was just googling around for some information and I found Toyota's video:

They explicitly say that some non-hybrids are able to switch:

[flash22]

The Hybrid (M15A-FXE) 3 pot (dynamic force engine) uses the miller cycle

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

https://en.wikipedia.org/wiki/Miller_cycle

[baxuz]

Was just reading that article a bit:

- Stratified combustion mode. Fuel is supplied at the end of the compression stroke, forming a charge of varying enrichment. This mode is used after a cold start, allowing to effectively ignite a lean (up to about 16:1) mixture, providing a higher combustion temperature to accelerate warm-up of the catalyst.
 

- Homogenous mixture mode. Fuel is supplied at the beginning of the intake stroke and is evenly mixed with the incoming air. Homogeneous air-fuel mixture is compressed and then ignited. Due to the evaporation of injected fuel, air charge in the cylinder is cooled improves cylinder filling.
 

Could this be the two modes of operation?

Also, yikes :X
 

Quote

• Upd. The bad news for European car owners: Toyota has refused to treat numerous problems with the EGR cooler as a design defect and a warranty claim.

 

[RickyC]

1 hour ago, flash22 said:

The Hybrid (M15A-FXE) 3 pot (dynamic force engine) uses the miller cycle

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

https://en.wikipedia.org/wiki/Miller_cycle

Exactly.  The correct name of the cycle used by Toyota engines ( and oher ones based on an Otto design ) is Miller.  

But probably  Aktinson is used for marketing and licence reasons ( Afaik Miller cycle is a Ford patent )

[Cyker]

Strictly speaking, neither is correct as the true Miller-cycle uses a supercharger to boost low-end torque, while Atkinson uses a complicated linkage to actually vary compression and expansion ratios rather than faking it with valve timing.

Of the two, it's definitely closer to the Miller cycle in operation tho'. I prefer to call it Miller because I mentally associate Atkins(on) with Diets and Miller with Beer and I like Beer better than Diets.

Really nobody cares which one is used apart from pedants as they both give the same gist.

As for the engine modes, AFAIK all the new Dynamic Force-branded engines can switch between Otto and Miller/Atkinson cycles as they have wider variable valve timing - Both the hybrid and non-hybrid ones. I think they did introduce it on some earlier engines tho - The only one I know of the top of my head is the 1.5L engine in the Mk3 Yaris that replaced the 1.33 1NR-FE.

 

[flash22]

Miller is both types in short it varies intake and exhaust cam opening duration to lower compression and reduce fuel usage also known as dvvti

The M15A non hybrid is direct injection, whereas the Hybrid is common EFI

 

 

[RickyC]

16 hours ago, Cyker said:

Of the two, it's definitely closer to the Miller cycle in operation tho'. I prefer to call it Miller because I mentally associate Atkins(on) with Diets and Miller with Beer and I like Beer better than Diets.

I perfectly agree 😀 

BTW I mentally associated Atkinson wit Mr. Bean 😀