Trip computer incorrect readings for average mph and both)

[Shak_ahmed]

Hi my trip computer is giving me incorrect readings for average mph and both mpg infant and average mpg, I’ve driven to Manchester and back, and the next day Liverpool and back with town driving about 10 miles, and it showing that my average speed is 18 mph, when I’ve driven between 65-80 mph on the motorway and normal speed limits in town, all on eco mode with stop/ start, and the average mpg showing is 37 mpg after driving over 200 miles, the mpg in town was showing 30.3mpg and average speed 11pms, how can this be fixed, or reset to get correct readings again 

[Shak_ahmed]

Instant not infant

[FROSTYBALLS]

Try disconnecting the Battery for 10 minutes to reset.

[Mooly]

Average speed readings soon fall dramatically once you come off a motorway. Remember it calculates all the time, not just when you are moving and so each junction and red light sees that average plummet. I do loads and loads of motorway and fast A roads and yet my average is usually around 26mph from memory. 

[mpm235]

18 hours ago, Mooly said:

Average speed readings soon fall dramatically once you come off a motorway. Remember it calculates all the time, not just when you are moving and so each junction and red light sees that average plummet. I do loads and loads of motorway and fast A roads and yet my average is usually around 26mph from memory. 

Yes true, if you stop at a few red lights, or are in a que for any length of time, it goes right down

[Wooster]

Only a suggestion - to echo what Mooly and mpm325 suggest.  With ample petrol in the tank, drive to the start of your motorway journey. Once underway, reset the average counters. Assuming the motorway was free flowing, when you've travelled 100+ miles, see what the average readings are.

[Shak_ahmed]

Thanks

[AisinW]

Averaging MPG is supposed to be at least 1 full tank or about 500 miles.  Otherwise, the calculations will have large error bar. I found the average MPG in Toyota is just spot on. If it does not match with full tank to full tank measurement, then  it is our own error refilling the fuel tank.

The instantaneous MPG and MPH is also ok. If we want to average only the trip on the highway, we can reset all measurement right when we enter the highway. 

The speed in speedometer is always faster than the actual speed 5-10% faster but the odometer is always spot on. It is simply to prevent blaming manufacturers if we got speeding ticket. 

[Shak_ahmed]

Thanks, I have filled up to a full tank last week and the range it said on the computer was 415 miles on my 1.33 Vvti tr engine, is this correct, as I think on a full tank it should be around 470 miles 

[Mooly]

It sounds about right although at the low end. The highest range displayed that I have seen with a full fill is around 456 but actual mileage covered would be much higher than that in my case. If you reset the ECU (Battery disconnect) you get that low figure. Providing your actual driving isn't to heavy footed that figure creeps up with each successive fill but never seems to go above the mid 450's despite a range (for me) of nearly 600 miles being possible. 

Have a look at this:

https://www.toyotaownersclub.com/forums/topic/157794-auris-133-fuel-bar-fuel-consumption-and-all-that-stuff/

As others have said, the calculated mpg can be very accurate and I see figures around 50 to 53mpg using E5 fuel.

[Shak_ahmed]

So for I have driven only done urban driving, to work and back, and have covered 142 miles and 3 bars have gone down, first one went down after 70 miles (range 340) and the second bar after 50 miles( range 290) just recently the third bar went ( range now is 285), I also disconnected the Battery and left it for 20 minutes before connecting it before I filled the tank, eco mode is on and air con is on at low setting, maybe I should disconnect the Battery again and leave it for much longer before connecting it again 

[Mooly]

If you disconnect the Battery the max range displayed with a full tank automatically falls to its lowest preset value which is 420 miles from memory. Each successive fill will see that figure rise but only to around 460 (that's about the highest I have reached) although I can easily exceed that range value in actual driving.

7 hours ago, Shak_ahmed said:

I also disconnected the battery and left it for 20 minutes before connecting it before I filled the tank, eco mode is on and air con is on at low setting, maybe I should disconnect the battery again and leave it for much longer before connecting it again 

I think little point tbh. It takes a surprisingly long time to fully relearn all the engine parameters such as idle speed.

The only thing that really matters is what your real and manually calculated mpg is and how it compares to the displayed average.

[AisinW]

We typically still have about 10L after the fuel light gauge is On. The range is only an estimation, calculated base on previous consumption.  I only go 100 miles max after the first fuel light is observed in my hybrid. 

Empty tank is not fun and we may get fined by police for unnecessary danger to people on the roads.