2019 Yaris Hybrid - Knocking Noise Cold Start

[PeterThePiper]

Our 2019 Yaris Hybrid has been sat for a few days. When I went to start it today I heard a knocking noise for a breif second as the engine kicked in. Whilst driving the car sounded fine.

What could be the cause for this noise and is it something to be concerned about?

 

[CPN]

...and this doesn't happen when the car has already been warmed up, yes?

(I don't like assumptions...)

[PeterThePiper]

No, once the engine has warmed up it idle's fine and runs smoothly.

This was the engine kicking in after starting it for the first time in a few days.

[CPN]

Then I would suggest that you stop worrying about it. My Mk3 did something similar when it was very cold; especially during the winter months. If you think about it, all the tolerances will be at their most contracted when it is exceptionally cold and everything will tighten up quickly after oil pressure and a little heat kicks in...

[CPN]

Just to be certain, the topic title says 2019 Yaris but your profile says 2017? Which is it?

Also, how many miles are on the clock and have you owned it from new?

[PeterThePiper]

I've updated my profile. 😀

I'm the second owner and it's done just over 40k

[CPN]

Ah ok, then nothing to change in what I have already said.

[1.33]

My Mk3 sounded similar after being parked up for 8 days. Had to lower the window to hear the ICE kicking in.

Despite being parked up, it reversed out of the garage on EV and the ICE kicked in when accelerating away.

[TonyHSD]

Ok, 

This is knocking is from ten clutch and it’s because of an engine misfire. 
Most common reasons are bad fuel, fuel mixture too rich, water or oil into air intake or coolant into air intake. 
Since it’s only very lightly and goes always quick I can suspect a bad fuel. Change your petrol station and preferably use e5 premium fuel from a non supermarket garages. 
 

[CPN]

10 hours ago, TonyHSD said:

Since it’s only very lightly and goes always quick I can suspect a bad fuel. Change your petrol station and preferably use e5 premium fuel from a non supermarket garages. 

My Mk3 only ever had e5 petrol in it and it still made that sound on a cold day (from new). I still think it is what I have previously said...

[PeterThePiper]

Thank you for your replies.

I usually fill up with Texaco Premium. The only exception was I used Tesco Momentum E5 last fill up.
But I believe there was also a short juddering previously which was before this refuel (when running on Texaco).

I showed my local toyota dealer where I bought the car from under a year ago and they said it wasn't normal so they want to take a look.

[MikeSh]

When left for days the oil drains out of most everywhere, so it takes a few seconds for the pump to refill all the galleries and bearings. Any clearances will rattle a bit until that happens, relying on the oil film still left to avoid serious harm. Obviously an older, more worn engine will be worse for this*.

( * Because the bigger clearances will rattle more and also allow the oil to drain faster meaning it will occur when the car is left unused for shorter periods.)

[Cyker]

If it does it every time you start the engine, whether it's cold or hot, there is a very small possibility the VVTi locking pin is jammed and allowing the VVTi cam to rotate before oil pressure has built up.

If it only does it when started stone cold, I'd lean more towards the above theories about the oil draining down and needing to be pressurised again.

[TonyHSD]

2 hours ago, PeterThePiper said:

Thank you for your replies.

I usually fill up with Texaco Premium. The only exception was I used Tesco Momentum E5 last fill up.
But I believe there was also a short juddering previously which was before this refuel (when running on Texaco).

I showed my local toyota dealer where I bought the car from under a year ago and they said it wasn't normal so they want to take a look.

100% from the petrol especially if it’s a cheap Tesco, it doesn’t matter if it’s e5 or e10. 
Just fill up with bp e5 or e10 , or Shell v power or regular 95 e10:and you won’t get these misfires. , or if you get those again they will be  less pronounced with minimal knocking from the clutch springs.
These cheap petrols are cheap for a reason and they definitely  has less additives inside, those who help reduce engine knocking and misfire. 
Blocked egr system can be another reason for those , but if that’s the case misfire will happen on hot engine too in certain conditions. Your ones are exactly like in my car and I am positive it’s from the fuel. UK fuels are not great quality, probably one of the worse from whole Europe. 

[Derek.w]

I try a petrol system additive like REDEX you can use it with any type of petrol even E10.

Its also sutable for HYBRID motors.

[MikeSh]

7 hours ago, TonyHSD said:

UK fuels are not great quality, probably one of the worse from whole Europe. 

That's weird. Other sources say UK fuels are better than some/many/all other countries.

There is the occasional foul-up but generally we have strict standards and checks. (The silicon fiasco a few years back was due to fuel imported from Europe iirc.)

7 hours ago, TonyHSD said:

100% from the petrol

Nothing, ever, ever is 100%. In your mind maybe, but never in reality.

[PeterThePiper]

The dealership couldn't find anything when they ran their diagnostics and checked over the engine.
It's not happened since so I think it was most likely to do with being stood for a few days in the cold.

I usually use premium mainly for the slightly lower ethanol content but I'll stick to Texaco & Shell in case it makes any difference.

[CPN]

On 12/28/2023 at 6:15 PM, TonyHSD said:

Your ones are exactly like in my car and I am positive it’s from the fuel. UK fuels are not great quality, probably one of the worse from whole Europe. 

I used to work in the Petrochemical sector for a number of years and that simply isn't true. Quite the reverse in fact. Fuels in Europe are generally inferior in quality (apart from Germany). Especially in Italy...

[TonyHSD]

No arguments, I have my thoughts only shared here. To me they are true, to others can be myths or in my mind. 
 

[flash22]

it clears within seconds, it's oil pressure building and lubricating, common with 0w20 oil, it tends to drain back to the sump if left for 5-6 hours, even more so if it is due a change

[TonyHSD]

This oil pressure building up sounds are different from the video shared. 
There are more similar to a faulty chain tensioner rather than the typical misfire noise knockings. 
The vvti sprocket noises also different from misfire ones, and closer to chain tensioner rattling but slightly heavier, more pronounced.
What op experienced is definitely a misfires and clutch plates springs overloaded. Usually an event that happened sometimes only on cold starts after some days of inactivity, 3 or more days.
The cheap supermarket fuels only adds to the problem or causes it. 
Here the oil pressure buildup rattling from my car after an oil change.