2.2 D4d Fuel Economy

[J White]

Hi all

Last week, my '55 Avensis went in for service. Before the service, I was averaging 45mpg on the on board read out. Since the service, this has dropped to 37mpg. I have refueled to reset the reading, as I initially though it might have been due to the amount of time the engine was idling during the service, but it is the same. I am pretty sure that the actual fuel consumption has not dropped by the suggested amount. I phoned the garage today and they fobbed me

off by saying that is is probably down to the cold weather, even though I have had the car for 2 years and never had such a low mpg in colder conditions as now.

The only thing that changed during the service was they had to change the ECU, as they blew the old one during an upgrade, but they said that this would not have caused this change. Once again, I felt as though they weren't bothered

I ended up suggesting that I would monitor it for the next 2 weeks and get back to them, but they didn't sound as though they would even look at the issue.

Does anyone have any ideas on what could cause this and whether I should take it up with them further?

Thanks

[striderwilson]

No idea what may have caused it, but would strongly advise sending a letter to the garage (recorded delivery) stating the problem (just the basics - 45mpg before service and 37mpg after), that you were unimpressed by their response on the phone and that you will monitor it for a specific period of time (ie the 2 weeks you mentioned) before writing to them again.

[tj1110]

Just had my 2.2d4d in for service and they updated ECU car now has more low down troque but mpg has gone down acorrding to computer read out before it went in used to get 46to50mpg now only get 39mpg Filled tank up yesterday i have done about 60 to 70 miles and its reading 38mpg.so we will see what it at after this tank full

[J White]

Have done a quick calculation of fuel consumption over 500 miles and it comes out at 45mpg, while the computer states 37mpg. I'd rather it was that way round, but I'm a bit concerned that a perfectly accurate on board consumption read out is suddenly way out after an update. Will phone the garage back with my findings and see what they say.

[caveman_si]

The moment you mess with the ECU in car it will change the mpg/power especaily if you have had it replaced.

In fact unpluging the Battery to reset the ecu to factory default is a common fix on some cars. Best thing is run it tank to tank and do the calculations manually to see what you get and if it is still way off take it back. But I have alway used on board mpg readings as a guide not the actual as they are often wrong.

There was post recently on auris forum about the 130% option dont know if thats on the avensis as everyone thinks it relates to the mpg accuracy.

I would be concerned though with the reason why the original ecu blew up during the update? Sounds like someone didnt plug something in correctly or shorted across something.

Hope you get it sorted.

[Q.S.]

Hi all

Last week, my '55 Avensis went in for service. Before the service, I was averaging 45mpg on the on board read out. Since the service, this has dropped to 37mpg. I have refueled to reset the reading, as I initially though it might have been due to the amount of time the engine was idling during the service, but it is the same. I am pretty sure that the actual fuel consumption has not dropped by the suggested amount. I phoned the garage today and they fobbed me

off by saying that is is probably down to the cold weather, even though I have had the car for 2 years and never had such a low mpg in colder conditions as now.

The only thing that changed during the service was they had to change the ECU, as they blew the old one during an upgrade, but they said that this would not have caused this change. Once again, I felt as though they weren't bothered

I ended up suggesting that I would monitor it for the next 2 weeks and get back to them, but they didn't sound as though they would even look at the issue.

Does anyone have any ideas on what could cause this and whether I should take it up with them further?

Thanks

Have you actually reset the average fuel consumption? If it is the same as mine (earlier model) filling up resets the range but does not reset the average fuel consumption. To reset average fuel consumption (on mine) you need to select average fuel consumption on the display, then press and hold the 'trip' button until a beep is heard and the display goes to 0mpg Av.

Average fuel consumption then begins a new calculation.

[J White]

Hi all

Last week, my '55 Avensis went in for service. Before the service, I was averaging 45mpg on the on board read out. Since the service, this has dropped to 37mpg. I have refueled to reset the reading, as I initially though it might have been due to the amount of time the engine was idling during the service, but it is the same. I am pretty sure that the actual fuel consumption has not dropped by the suggested amount. I phoned the garage today and they fobbed me

off by saying that is is probably down to the cold weather, even though I have had the car for 2 years and never had such a low mpg in colder conditions as now.

The only thing that changed during the service was they had to change the ECU, as they blew the old one during an upgrade, but they said that this would not have caused this change. Once again, I felt as though they weren't bothered

I ended up suggesting that I would monitor it for the next 2 weeks and get back to them, but they didn't sound as though they would even look at the issue.

Does anyone have any ideas on what could cause this and whether I should take it up with them further?

Thanks

Have you actually reset the average fuel consumption? If it is the same as mine (earlier model) filling up resets the range but does not reset the average fuel consumption. To reset average fuel consumption (on mine) you need to select average fuel consumption on the display, then press and hold the 'trip' button until a beep is heard and the display goes to 0mpg Av.

Average fuel consumption then begins a new calculation.

The average fuel consumption does reset on filling up.

[Groovy Mucker]

The average fuel consumption does reset on filling up.

Obviously does on some models. Certainly doesn't on my 07 model (which I think is better: it allows you to monitor over as long as you want - assuming you want to trust it, that is).

[MPJones]

Hi all

Last week, my '55 Avensis went in for service. Before the service, I was averaging 45mpg on the on board read out. Since the service, this has dropped to 37mpg. I have refueled to reset the reading, as I initially though it might have been due to the amount of time the engine was idling during the service, but it is the same. I am pretty sure that the actual fuel consumption has not dropped by the suggested amount. I phoned the garage today and they fobbed me

off by saying that is is probably down to the cold weather, even though I have had the car for 2 years and never had such a low mpg in colder conditions as now.

The only thing that changed during the service was they had to change the ECU, as they blew the old one during an upgrade, but they said that this would not have caused this change. Once again, I felt as though they weren't bothered

I ended up suggesting that I would monitor it for the next 2 weeks and get back to them, but they didn't sound as though they would even look at the issue.

Does anyone have any ideas on what could cause this and whether I should take it up with them further?

Thanks

I have just changed the glow plugs on my 53 Avensis, taken the negative terminal off the Battery to get rid of the warning lights and the MPG reset to 0.0 as an average, as a result I have managed to get the average upto 44 by careful driving, though before I was getting 50-52 MPG as an average. This is a similar drop to what you have experienced, have I reset something in taking the Battery off? Has anyone any ideas on this. Many thanks.

[Q.S.]

The average fuel consumption does reset on filling up.

Obviously does on some models. Certainly doesn't on my 07 model (which I think is better: it allows you to monitor over as long as you want - assuming you want to trust it, that is).

Seems strange that it doesn't reset on fill up with 02 or 07 models but does on a 55.

My 02 model is the same as the above 07 and calculates over however long it is left running. Starts a new calculation when reset manually. I personally reset every fill up to keep a constant check, that way if anything goes amiss to affect fuel consumption it is spotted straight away. I also reset the trip odometer at the same time and I find the onboard trip computer to be pretty accurate.

[thezoo111]

I have just purchased a 2.2 D4D and been keeping an eye on the fuel economy via the computer against working it out manually by resetting the trip and working out the fuel used over miles travelled and there is a big discrepancy.

The computer tells me that I have achieved an average of 48.4 but the trip indicates 504.3 miles travelled and when I refuelled I put in 54.68 litres (12.04 gallons) and this equates to 41.88 MPG when working it out manually.

Can anybody explain the difference.

Also why does the fuel range increase to reflect how many miles should be left in the tank when the average MPG figure goes up, lik eit does in other cars I have access to on a regular basis in my job .

Thanks

[2912pwil]

I have just purchased a 2.2 D4D and been keeping an eye on the fuel economy via the computer against working it out manually by resetting the trip and working out the fuel used over miles travelled and there is a big discrepancy.

The computer tells me that I have achieved an average of 48.4 but the trip indicates 504.3 miles travelled and when I refuelled I put in 54.68 litres (12.04 gallons) and this equates to 41.88 MPG when working it out manually.

Can anybody explain the difference.

Also why does the fuel range increase to reflect how many miles should be left in the tank when the average MPG figure goes up, lik eit does in other cars I have access to on a regular basis in my job .

Thanks

"Explaining the difference". The computer is wrong.

(I'm a 35yr+ experienced IT man): The Computer is (er... actually the ****er who wrote the software) often wrong, whatever the salesman says. IMHO fiddling with something like the device that works the numbers out to try & fix it is only likely to end in tears, sorry.

Mine's out a bit also, but not by anything like so much. Just motored down frae the Highlands of Scotland where I live to visit the wife (mine) in Berkshire. Just re-filled up after 565.3 miles with range still showing 49 miles. Seemed to work out about 52mpg, but then I've got a 'bus pass and tend to cruise @ 60mph [yup, sad isn't it]. Better mileage than the Lexus GS300 3litre auto petrol I just sold for scrap. Never worked out the mileage on that, knew I'd be too disappointed... Back tae Scotland later this month...

Yours aye...

[Dunkelmann]

"Explaining the difference". The computer is wrong.

(I'm a 35yr+ experienced IT man): The Computer is (er... actually the ****er who wrote the software) often wrong, whatever the salesman says.

(I'm a software engineer with 35 years experience in the industry, working on mathematical models):

Mr experienced IT man you should have heard about "garbage in, garbage out" by now! I don't agree with you.

The programmer who wrote the software, and the processor are very unlikely to be wrong. We are not talking about 12 year olds playing with Basic but professionals trained in real-time systems. We are talking about real-time (think microseconds and milliseconds) sensor inputs to measure revolutions of a rotating system, fluid flow in the engine management system and fluid volume sensors in the fuel tank where fluid slops around. Sensor accuracy will vary between cars.

Not only that, but exactly the same processor and program are in each of the computers for a particular model, therefore any differences between two cars will be down to the data fed into the programs. Given the same data, each individual car computer will produce exactly the same result.

My 2.0D4D computer mpg can be pretty damn close, other times (usually when the wife fills up!) it's within 10%. Every car I have I record the car mpg and estimated mpg. I fill up and using the mileage since the last fill, together with the fuel used, I hand-calculate the mpg. I keep a spreadsheet since I'm a bit of a geek. So the other variable in all of this is whether you are filling up to exactly the same point on the tank each time. Relying on the pump nozzle is not reliable since different pumps will switch off at different times. I wait until I see the fuel bubbling back up - that is a much better measure.

I reset the mpg back to zero on each fill up.

So, a little care on filling up and working out your own mpg will give you a better indicator. After several fill ups you'll see how much out on average your computer is. Live with it - it's the sensors not the computer!

[ptri]

I doubt if you can get better than +/-0.5 litre consistency between fill-ups even if you are very careful and use the same pump, so calculations should be done over several fill-ups to minimise this inaccuracy. For my Avensis, the calculated mpg is usually, but not always, better than that indicated. I've just gone through my records and compared the indicated mpg (I always reset it on fill-up) with the calculated mpg over 46 fill-ups by calculating the number of gallons I would have used based on the mpg reading. The result is that the mpg reading is 3.0% pessimistic compared to the calculated mpg (ie an indicated 50.0 mpg is most likely to be 51.4mpg). I think this is about as accurate as you can expect/need for injecting fuel. PS my Fiat Panda's mpg indicator is 12.1% optimistic with this calculation - which is really bad!

[irishjay]

lol the fuel mpg is the least of your problems ,,, just be prepared for your head gaskets to go many times over oh yeh and injectors