Knocking noise 18-20 seconds after start then lasts for 20 ?

[ROYALE]

Hi Guys 

I have just got my yaris mk4 and noticed a knocking noise after 18-20 seconds

i took back to toyota dealer in aberdeen and was told this is a 1.5 engine caracteristic !!!

is this true

all help appreciated 

 

thank you

[flash22]

It starts after 30 sec of the engine starting, sound like a misfire or blowing exhaust ? Goes away if you press the throttle ??

[Bernard Foy]

4 hours ago, ROYALE said:

Hi Guys 

I have just got my yaris mk4 and noticed a knocking noise after 18-20 seconds

i took back to toyota dealer in aberdeen and was told this is a 1.5 engine caracteristic !!!

is this true

all help appreciated 

 

thank you

Yes it's true, and a lot of new owners have mentioned it in post. I don't even hear it now. 😃

[Big_D]

Yes, quite normal

[TonyHSD]

Knocking noises because of engine misfire are not normal and also not good at all. 
The best op can do is to record a video and share.
Use e5 99 and premium fuel usually help prevent these unpleasant sounds.  

[mr_blibby]

18 hours ago, ROYALE said:

Hi Guys 

I have just got my yaris mk4 and noticed a knocking noise after 18-20 seconds

i took back to toyota dealer in aberdeen and was told this is a 1.5 engine caracteristic !!!

is this true

all help appreciated 

 

thank you

Had it with mine. Only done c 600m and it now seems to be noticeably quieter than at new. Also tried using e5 which may have made a difference

[flash22]

10 hours ago, TonyHSD said:

Knocking noises because of engine misfire are not normal and also not good at all. 
The best op can do is to record a video and share.
Use e5 99 and premium fuel usually help prevent these unpleasant sounds.  

It's just the way they are, it's a very distinct pattern

[TonyHSD]

The knocking noises that comes from misfire are not typical 3 cylinder engine sounds, they does indeed sound similar but those metallic clunks are damper springs fully loaded and next step overload and break, or premature wear, slip , hybrid system malfunction, we all know it. 
Because that happens to a new cars it doesn’t mean it’s normal but shows how bad are the fuels in uk. You here these on your cold starts , next fill up change the petrol station or the fuel grade. 
All that said if we are talking about same metallic knockings like on gen3 hybrids when they have egr issues. 
For reference I don’t have Yaris but my many of my neighbours  does and hear those how they sound, once I was amazed how quiet was running a Yaris mk4 icon from 2021, almost no engine noise at all but just the mg1 whining to charge the Battery, so good. 

[flash22]

Nope nothing wrong it's just a sound the hybrid makes on a cold start, all engine parameters are in spec, no codes, no miss fires - nothing to do with fuels either

even had the stethoscope out on many occasions

[TonyHSD]

1 hour ago, flash22 said:

Nope nothing wrong it's just a sound the hybrid makes on a cold start, all engine parameters are in spec, no codes, no miss fires - nothing to do with fuels either

even had the stethoscope out on many occasions

That’s the typical 3 cylinder engine sound plus added mg1 load . 
I agreed with that it’s normal but if any metallic clunks like on Prius hybrids from the clutch then it’s not ok. 
 

[ROYALE]

Hi GUYS

i have listen to 4 other 1.5 yaris hybrids and they all do they same 

What the xxxx is it no one seems to know

 

thanks

[ROYALE]

also does it when hot

[flash22]

Not sure, it is either emission related or charging related

Possibly EGR or GPF pre heat ?

[MikeSh]

3 hours ago, ROYALE said:

What the xxxx is it no one seems to know

These engines can run two (or maybe more*) different 4-stroke cycles depending on what the computer wants at the time. It's probably just changing over from one to another.

* Eg. the Atkinson cycle, the Otto cycle, and the high-efficiency hybrid cycle (HEHC).

[TonyHSD]

Can you record these knocking noises and share with us? 
Does these happen all the time or only sometimes? 
When press accelerator further does the knocking disappear? 

Definitely not a normal engine sound if you have clutch bangs as result of misfire and these can be as bad as they sound as they lead to broken springs on the clutch plate and more. 
Last time someone here reported these and he had coolant leak into cylinder one, it’s a high mileage Yaris from abroad. Egr cooler issue. 
 

[Tommy X]

4 hours ago, flash22 said:

Not sure, it is either emission related or charging related

Possibly EGR or GPF pre heat ?

Probably this is the case, some engines r e t a r d  the ignition timing when cold started to heat up the cat, a Mazda I owned sounded like a bag of spanners on cold start but it was normal

[Chas G]

My 22 yaris cross used to an odd tinkling rattling sound sometimes on start up but fairly quickly disappeared. Amongst all the other odd noises it made it didn't bother me unduly.

[Derek.w]

I used to have a knocking noise at startup so treated the petrol with REDEX it sutable for hybrid engines.

Still use it now and then.

[TonyHSD]

That’s the thing, the knocking noises sounds the same because comes from the clutch plate springs however the reasons can be different. 
Often is from the fuel and these usually comes with a smell of raw petrol from exhaust - water in or simply bad quality- petrol or injectors issues, happens sometimes to me too when I have e10 or cheap supermarket fuels. 
Coolnat in - like on the high mileage Yaris. 
Bad spark plugs or coils can cause same issues too but these likely to trigger warning light. 
On your cars not too old I guess is very likely to be from the petrol quality in uk and particularly the e10. 

[jthspace]

11 hours ago, Derek.w said:

I used to have a knocking noise at startup so treated the petrol with REDEX it sutable for hybrid engines.

Still use it now and then.

Aldi sells it in a double-pack for £5, half the price of a petrol station. They do diesel version as well.

[flash22]

15 hours ago, TonyHSD said:

Can you record these knocking noises and share with us? 
Does these happen all the time or only sometimes? 
When press accelerator further does the knocking disappear? 

Definitely not a normal engine sound if you have clutch bangs as result of misfire and these can be as bad as they sound as they lead to broken springs on the clutch plate and more. 
Last time someone here reported these and he had coolant leak into cylinder one, it’s a high mileage Yaris from abroad. Egr cooler issue. 
 

Its perfectly normal, it just a characteristic of the M15A-FXE, it's within set period of time for a specific period of time

 

[YarisHybrid2016]

I've heard these engines make some really interesting noises.

A good one is cold-start when ambient temp is around freezing. You get initial start-up, then EGR (I think?) recirc 30 seconds later. After 5 minutes or so (HV Battery usually stopped charging by this point with associated change in engine noise) the engine noise changes AGAIN, and can catch you off-guard.

One time, the engine seemed to enter a super-slow idle and that freaked me out as I thought it was already at idle, but it seemed like it was at 600 RPM (i.e., very slow). Still smooth and seemed intentional due to how it transitioned there. Only ever heard that once. It sounded a really deep roar, as if you had taken the exhaust off. I can't even describe it.

All this was with the heater on to demist.