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I get Low mpg. What should it be.


Ali84
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Hi guys and gals. This is my first post. I have a prius plus imported, and only been driving it for 2 months now. 

Its a 2014 cx model, 1.8.ltr with 140000km on the clock. 

I'm unsure on its service  history or clutch change as all docs are in Japanese. 

As usual I put in £20 petrol when I fuel up, that's about 14 litres. I drive in ECO mode and hardly ever switch to power mode as I am only doing local computes. 

I am only getting 75km (46 miles) for 14 litres.  This looks really low to me, as my other cars were 2ltr diesels, and 1.4 petrols were giving a lot more. 

I reset the meter l, and I did a 120 mile trip on the motorway, I put in a full tank and only used half on motorway , the remaining half tank was used on local roads. On this occasion I only got 260km that's 161 miles. 

Has anyone else had similar mpg? 

What's the usual cause? 

And what mpg should I be getting? 

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6 minutes ago, flash22 said:

Is the engine running most of the time ?, something is a bit off as you will get 15 mpg from a 5.7L V8

Any lights on the dash ? any codes stored ?

Hi, I got no warning lights, no wierd noises. I havent had a diagnostics machine plugged in yet. 

The mpg is really low, I may try a clutch change but unsure if this may help towards better mpg. 

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The prius doesn't have a clutch, they are automatic

Any pics of the consumption display ? have the gauges be recalibrated to show MPH instead of KMH ?

What car do you have the Prius plus as in your profile or a prius CX - PM me the vin/frame number

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21 minutes ago, flash22 said:

The prius doesn't have a clutch, they are automatic

Any pics of the consumption display ? have the gauges be recalibrated to show MPH instead of KMH ?

What car do you have the Prius plus as in your profile or a prius CX - PM me the vin/frame number

Its a prius plus 7 seater has a CX Badge on the tailgate. The speedo was changed to MPH when the dvsa check was done. But the trip computer still shows km. Will get you the vin number later if still needed. 

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Could be related to the traction Battery, as it's near its end of life, it's not able to store energy as it did when it was new. Therefore, the petrol engine kicks in more often. You need to go to a dealer and run a hybrid system test. You cannot perform such a test at any service shop as you need special access to the TME webpage and the GTS software in order to execute the test.

One other thing to have in mind is the traction Battery blower fan filter, it might be full of dust, you need to clean that (look in the manual, it should be near the traction Battery, in the back seat).

Prius or any other Toyota hybrid doesn't have a clutch, the hybrid transmission is composed of a generator (sometimes also used as a starter for the petrol engine), a traction motor (also used to recharge the traction battery when braking), planetary gear system and the differential.

The generator is connected to the sun gear whereas the petrol engine is connected to the planetary gears carrier; the sun gear is engaged with the three planetary gears and all these are rotating inside the ring gear; there are some reduction gears between the ring gear and the traction motor and differential. No clutch anywhere. There is just a torque damper between the engine and the hybrid transmission.

 

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1 hour ago, Catlover said:

Can you see on the dashboard graphics whether the hybrid battery is charging and discharging.?

Hi. Thanks for the reply, yes the Battery on display does show charge bars. 

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28 minutes ago, DorinA said:

Could be related to the traction battery, as it's near its end of life, it's not able to store energy as it did when it was new. Therefore, the petrol engine kicks in more often. You need to go to a dealer and run a hybrid system test. You cannot perform such a test at any service shop as you need special access to the TME webpage and the GTS software in order to execute the test.

One other thing to have in mind is the traction battery blower fan filter, it might be full of dust, you need to clean that (look in the manual, it should be near the traction battery, in the back seat).

Prius or any other Toyota hybrid doesn't have a clutch, the hybrid transmission is composed of a generator (sometimes also used as a starter for the petrol engine), a traction motor (also used to recharge the traction battery when braking), planetary gear system and the differential.

The generator is connected to the sun gear whereas the petrol engine is connected to the planetary gears carrier; the sun gear is engaged with the three planetary gears and all these are rotating inside the ring gear; there are some reduction gears between the ring gear and the traction motor and differential. No clutch anywhere. There is just a torque damper between the engine and the hybrid transmission.

 

Thanks for this. Very informative. I will look into the traction Battery and the blower fan filter too. Thank you for all the help. 

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I would check the filter first. If the traction Battery overheats because the blower isn't able to cool it (dust in the filter), the Hybrid Vehicle ECU will use only the Petrol engine and avoid using the electrical one (protecting the battery).

It happened to me on the Corolla, I was carrying a lot of clothes on the back seat and the Battery ventilation hole got covered. So I could hear the blower kicking in hard and then, after a few miles, I could see the petrol engine working most of the time, when it should have been off.

In my case, it went away after clearing the clothes from the blower ventilation hole.

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18 minutes ago, DorinA said:

I would check the filter first. If the traction battery overheats because the blower isn't able to cool it (dust in the filter), the Hybrid Vehicle ECU will use only the Petrol engine and avoid using the electrical one (protecting the battery).

It happened to me on the Corolla, I was carrying a lot of clothes on the back seat and the battery ventilation hole got covered. So I could hear the blower kicking in hard and then, after a few miles, I could see the petrol engine working most of the time, when it should have been off.

In my case, it went away after clearing the clothes from the blower ventilation hole.

I can't find the filter. The 5 seater has it on the floor of the rear seats, unsure where it is on the 7 seater model. 

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2 hours ago, Ali84 said:

Hi. Thanks for the reply, yes the battery on display does show charge bars. 

Do the charge bars move ie go up and down.vifvtjey don’t move that may mean a problem with the hybrid Battery, that is the big one under the seat.

Get the hybrid Battery checked out, as suggested, by Toyota. It’s the Hybrid Health Check, will cost about £45, but free if you have your car serviced. An ok hybrid Battery will give you 12 month warranty on that battery.

Have you checked the engine air filter? It may be blocked thus not allowing correct amount of air in combustion chamber thus higher fuel consumption. When was the vehicle last serviced, engine oil should be 0w-20. A Toyota dealer service could give you a 12 month warranty at no extra charge, it’s the new Toyota Relax scheme. BUT There again the Relax scheme probably doesn’t cover an import vehicle.

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Perhaps wrong calculations, worst fuel consumption in this particular model should be 40+mpg , they usually do 50-55mpg motorway and up to around 60-65mpg town , in traffic jams again around 55mpg. 
Had few of these before and they are great cars, comfy and specious 👍 Hybrid Battery is actually located in the middle console between  front seats, fan filter perhaps somewhere on the front console or under the seats. 👌

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Hi guys thanks for all the responses. 

I did a little check to make sure I was getting correct calculations.

The obd display shows in km but actually is in miles. My bad I was mislead by the km sign. 

I can now confirm I am getting 75 miles to 14 litres of fuel, that's short journeys from 2 miles upto 10 miles.  However the trip display does show 25 mpg on my last recorded trip. 

I think I will have the service done with a general Battery health check. 

Sorry for all the confusion, this is my first hybrid and Japanese car. 

 

 

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That's still poor around 25 mpg, are the brakes binding/getting hot, at 1/8 throttle the prius should get up to 25-30mph on electric

if you have a smartphone get yourself a bluetooth/wifi obd2 dongle and download the Dr Hybrid or hybrid assistant

 

I'm not sure if a main stealer will do a HHC as it's a Jap import, tbh the customer just gets a pass or fail it doesn't tell you much else

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Yah, both my dealers categorically stated they won't do anything if the special hybrid stuff with hybrid imports and would just treat them as they would any other third-party car. (This was when I was considering importing a japanese-spec Mk4 :laugh: )

Still, if you have a good dealer they might be willing to at least try...

There are specialists that will work on import hybrids but finding them is the trick...!

 

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The engine is an engine. Get that serviced at any competent garage. A Toyota independent specialist should be able to check the hybrid Battery.

25mpg is better, but even if the hybrid Battery is not working you should be able to get 30+mpg I reckon.

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Hybrid Battery if not working or not at its minimum threshold there will be warning lights on the dash and messages “hybrid system malfunction “ please visit Toyota dealer. Any dealer should take care of customer and inspect, diagnose and repair the car no matter where and how the car came from., no warranty given, custumer pays gets serviced, simple. 25mpg is way off real mpg these cars deliver. Short town trips , cold weather, if the car is fully loaded can affect but not as much. My advice to the op is to fill up full tank reset all numbers daily mileage, consumption, time elapsed, and drive the car for at least half tank gone, then refill again and do the maths and we will take it from there. About the service, if you are a diy person doing it yourself is the best, if not trusted mechanic friend or garage that you know can help too, get it properly serviced, clean fan filter, check tyres pressure and make sure brakes are not binding and you will be ok. If there is a problem with the car you most likely get engine management light on and other warnings. 
Good luck 

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Over the years on this forum, low mpg has been caused by:-

Wrong type of engine oil

Tyre pressures too low

Tyres not low rolling resistance type

Winter (cold, wind, rain, snow, having heating on)

Roof bars

Brakes not releasing fully

Traction Battery fan vents blocked

 

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2 hours ago, johalareewi said:

Over the years on this forum, low mpg has been caused by:-

Wrong type of engine oil

Tyre pressures too low

Tyres not low rolling resistance type

Winter (cold, wind, rain, snow, having heating on)

Roof bars

Brakes not releasing fully

Traction battery fan vents blocked

 

I check all the tyres, no roof bars, air vent to Battery in centre console is under driver seat and has no mesh is clean. 

The oil is very clean and air filter in engine bay was clean also. The previous owner in Japan had kept it in good condition. Looks new in and out even with 140km.

 

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Clean oil does not indicate the correct grade of oil was used on last service.

I would recommend a Toyota dealer service and hybrid check.

Considering on a warm day I get over 80MPG on my Gen4 Prius and over 70MPG on a cold day. Your fuel consumption does not appear to be what other Prius users get.

I hope you can get the answer to your problem. 

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