Strange hybrid behaviour

[Instructor_geoff]

Good morning all.

 

First post here. I have used various owners' forums in the past and found them to be a wealth ofimformation and knowledge.

I have a 3.5 year old Yaris Hybrid (2014 mode bought from new) that I use as a tuition vehicle for my driving school. Great car, except it has started to behave a little oddly. 

When lifting off the accelerator, the engine normally shuts off, or at least goes to idle if the engine is needed. Nowadays, it continues to revs hard for 2-3 seconds when I lift off, then spends 10 seconds at what sounds like about 2500rpm before finally shutting off and the car returning to EV mode. 

When it is in this 'mood', the cruise control behaves oddly as well. When descending a hill with cruise control, instead of using regenerative braking to control the speed, it revs the engine hard as if the gear is in B mode. 

Looking at the trip computer, it's clear it is not generating power by showing the little E symbols. The bar graph just showing poor economy. It's as if it's not using the hybrid system at all. 

I have figured out what sets this all off. One enthusiastic use of accelerator in a journey will set the car into this mode. It really does feel like it's switched into a different mode altogether. 

 

In th first 3 years, it did this a handful of times, now it will happen very day. 

 

Before I go to a main dealer and pay a fortune for them to connect the OBDii readers, does anyone have any idea what's going on?

[Anthony Poli]

Maybe the hi Battery cooling fan has got clogged with fluff. That can be enough to cause the ice to stay on, rather than shut off.

 

 

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[Anthony Poli]

Maybe the hi battery cooling fan has got clogged with fluff. That can be enough to cause the ice to stay on, rather than shut off.

 

 

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Hv not hi (pesky autocorrect)

 

 

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[Instructor_geoff]

38 minutes ago, Anthony Poli said:

Maybe the hi battery cooling fan has got clogged with fluff. That can be enough to cause the ice to stay on, rather than shut off.

 

 

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I think you're on to something. I was at a garage when I wrote the original post, getting the 12v accessory Battery changed as it's completely knackered. While helping the mechanic get the plastic trim off from under the back seat, I noticed a grille in the plastic trim, and a filter beside the Battery packs. It had a THICK layer of fluff on it, which I removed promptly.

I have since read your reply, so checked the the grille and I could feel air being pulled through it at quite a rate. There must have been zero air flow before.

I then drove away in a 'spirited' manner and the car has more power again, and the car didn't change its behaviour after.

I would never have linked the two.

I guess when I asked for a lot of power, the electronics and batteries got hot, and didn't like the lack of airflow. So it stopped the regeneration and relied more on the engine. Makes perfect sense. 

Awesome. Thanks for your reply! 

[Cyker]

Ooops nevermind!

[Anthony Poli]

Maybe the hi battery cooling fan has got clogged with fluff. That can be enough to cause the ice to stay on, rather than shut off.

 

 

Sent from my iPhone using Tapatalk

I think you're on to something. I was at a garage when I wrote the original post, getting the 12v accessory Battery changed as it's completely knackered. While helping the mechanic get the plastic trim off from under the back seat, I noticed a grille in the plastic trim, and a filter beside the Battery packs. It had a THICK layer of fluff on it, which I removed promptly.

I have since read your reply, so checked the the grille and I could feel air being pulled through it at quite a rate. There must have been zero air flow before.

I then drove away in a 'spirited' manner and the car has more power again, and the car didn't change its behaviour after.

I would never have linked the two.

I guess when I asked for a lot of power, the electronics and batteries got hot, and didn't like the lack of airflow. So it stopped the regeneration and relied more on the engine. Makes perfect sense. 

Awesome. Thanks for your reply! 

 

 

Sometimes it’s the simplest of things that cause big issues. Glad it’s back to normal again

 

 

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[YarisHybrid2016]

There was someone else here recently had the same trouble, due to fluff.

Pleased it's fixed!

Out of interest, how deep into the cooling system was it? I checked mine a couple of weeks ago and it appeared to be clear, but I couldn't see beyond the front aperture grill.

[Instructor_geoff]

There is a fine mesh screen behind the plastic trim. You'll need to remove all the trim from under the rear seats, and then you can get to the mesh. The amount of fluff must have completely eliminated the airflow to the HV batteries. 

When the car car is running, I can feel air being pulled into the vents easily. 

Im surprised that Toyota doesn't make owners aware of this, and that there is no warning light or anything to alert drivers to this issue. The car knew something was wrong as it wasn't driving properly. Surely a warning light would be helpful? 

[Anthony Poli]

 

It should have been designed better, a warning light to indicate low air flow.

 

 

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[YarisHybrid2016]

I thought the same thing when this topic was raised previously! Just thermal monitoring of the pack and an overheat lamp for the Battery might be sufficient.

Even in the middle of summer the Battery won't be above 50 C in operation.

Now I think about it, I'm surprised there isn't a Battery overtemp warning.

Design oversight?? There must be battery thermal monitoring??????

[Devon Aygo]

The filter, the effect its blocking can have, location and its maintenance is included in the owners manual ( quick check on a 2014 Yaris copy from "myToyota" has info on pages 53 and 56) later cars 2015 facelift > add a light on the dash ( yellow spanner with ! ) to indicate reduced air flow. All cars have a warning light to indicate a significant over heating of the Battery, invertor etc.

From my own experiences we don't tend to see many issues and those we do tend to be in cars with pets & high traffic in cabin such as Taxis etc

[Anthony Poli]

Is the mg temperature going to high cause the same effect?

On a long motorway trip I actually saw my mg temperature as high as the ice coolant temperature.

 

 

 

 

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[Devon Aygo]

29 minutes ago, Anthony Poli said:

Is the mg temperature going to high cause the same effect?

On a long motorway trip I actually saw my mg temperature as high as the ice coolant temperature.

 

 

 

 

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What temperature are you determining as being "Too high"?

[Anthony Poli]

It was curiosity, after looking at the hybrid reporter graph showing the mg temperature was about 90 degrees. Roughly matching the normal ice temperature.

 

 

 

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[Devon Aygo]

According to the repair manual 80-110 degrees is normal operating temp for the MG and invertor unit, should coolant temps exceed 110 degrees a warning light will illuminate and power be reduced until temperatures drop back into the normal