Computer MPG computer wrong reading

Dave Taylor · 5th November 2006, 16:56

Hi

I have now filled my 1.8V-Tech up twice, on both occasions the Computer was telling me I was getting 41 - 42 MPG but both times I calculate 37 - 38 MPG. Which is a long way out, my wife’s Jazz is spot on.

I do an 18 mile journeys to work A & B roads used to get 37 MPG from my previous 1.6 car so I was amazed when the Computer said 42 MPG.

So I am disappointed twice, once because the car is less economical then it told me it was and twice because there is now something wrong with it.

Has anybody checked the actual MPG against the computer reading?

And what are other 1.8V-Tech owners getting regarding MPG?

Regards, Dave

3rd Honda · 5th November 2006, 17:37

I have always checked mine by 'full tank refill/miles covered' and it usually agrees within 1 mpg, though occasionally up to 2 mpg optimistic on the car's display. The tendency is for the car's display to be a bit optimistic.

steve · 5th November 2006, 18:57

I have checked my 2.2 ex from new. done about 3000 miles and it usually 2 to 3 mpg optimistic on the car's display. but still getting 50mpg + so well happy.

Billybobbo · 5th November 2006, 20:56

Mines the same - the electronic MPG is almost always 10% over the actual mpg. At least 10% is easy to deduct in my head to get a realistic reading at a glance. Personally I think if Honda are going to bother fitting an electronic mpg meter they should at least try and get it more accurate than this, otherwise, they might as well have not bothered!

pcr · 5th November 2006, 21:15

There's another thread where the concensous is that it reads too high, so I would assume that this is intended, for obvious reasons.

TTDegs · 6th November 2006, 01:07

except that...

Does anyone have a for sure, 100% certain answer as to which calculation using what mileometer or other method of measuring distance?

We know that the speedo reads high.

I don't know for certain if the mileometer therefore reads high too?

We're pretty sure that the 'real time' fuel use guage is based on how much fuel is being squirted through the injectors.

But I have no idea how it works out the mpg for the tank (or since reset) - but I don't think it's based on the entire distance since filling up - mine fluctuates too much for that...

all of which doesn't help a great deal (sorry!), other than to say that I use my mpg display as an indication - it's not like I base my fuel buying decisions on it

323GT-R · 6th November 2006, 08:31

The thing I have found with mine is that the MPG per tank reading varies quite a bit depending on how you drive immediatley after the reset - I have mine set to reset on fill up. The long term MPG, that I've now got about 6000 miles on seems to be more accurate.

If you fill the car up, then drive hard immediately for a few miles, the average MPG for that tanks starts low, and never seems to recover. If you drive very gently after a fill up for a while, the MPG reads high.

Typically I see about 480 - 500 miles between fill ups, best I've managed is 530 miles, worst was 440. On a 45 litre fill up, which is about where the warning comes on on my car, that's 44MPG worst, 53MPG best, 49MPG average. The long term average is now showing 49.2 MPG, so pretty much bang on over the last 6K miles. The MPG per tank has varied from 38 - 56MPG on different tanks! It must be something to do with the way it's calculated...

4gotten · 6th November 2006, 18:25

I have 1.8 petrol Civic. I checked the actual MPG against the computer reading several times. I must say that computer is always to optimistic. In my case it is that the lower MPG, the bigger difference between actual and computer reading. It always varies from 2 to 5 MPG.

pjelsworth · 6th November 2006, 19:21

Quote:

Originally Posted by TTDegs

I don't know for certain if the mileometer therefore reads high too?

I think there is a regulation about this. It wouldn't do to have this wrong one way or the other

Dave Taylor · 8th November 2006, 19:34

Quote:

Originally Posted by 4gotten

I have 1.8 petrol Civic. I checked the actual MPG against the computer reading several times. I must say that computer is always to optimistic. In my case it is that the lower MPG, the bigger difference between actual and computer reading. It always varies from 2 to 5 MPG.

Hi 4gotten, What MPG do you actually get?

Could other 1.8 owners also tell me mhat MPG they actually get?

Regards, Dave

bounce75 · 8th November 2006, 20:23

My 1.8 SE has averaged 42mpg over the last 3 weeks on various journeys.

Dave Taylor · 8th November 2006, 20:28

Quote:

Originally Posted by bounce75

My 1.8 SE has averaged 42mpg over the last 3 weeks on various journeys.

Thanks for the reply, is that what the on-board computer is saying or is that what you calculated i.e Miles driven / petrol actually used?

4gotten · 8th November 2006, 21:13

Quote:

Originally Posted by Dave Taylor

Hi 4gotten, What MPG do you actually get?

Could other 1.8 owners also tell me mhat MPG they actually get?

Regards, Dave

I had my car for over a month and I drove 2600 km (ca 1600 miles).
According to my calculations my MPG is 41. I am happy with that. MPG is the same as I had when I used to drive Hyundai Accent 1.5 petrol but it had 50 hp less.

Glasex · 10th November 2006, 00:25

Hi,
when the motor is running and the car is stopped, does the MPG computer indicates any value for the instant consume??? My actual car indicates 0 MPG (SEAT IBIZA and waiting for a HONDA CIVIC 2.2 EX) ... so i believe that could be a possible reason for the difference between real and the MPG computer information ...

Regards

PS: Sorry for the bad english

4gotten · 11th November 2006, 23:02

Quote:

Originally Posted by Glasex

Hi,
when the motor is running and the car is stopped, does the MPG computer indicates any value for the instant consume??? My actual car indicates 0 MPG (SEAT IBIZA and waiting for a HONDA CIVIC 2.2 EX) ... so i believe that could be a possible reason for the difference between real and the MPG computer information ...

Regards

PS: Sorry for the bad english

In this case my computer indicates an average consumption( in general it is increasing) but temporary fuel consumption shows zero on the display.

elbe35 · 13th November 2006, 20:44

Hi, my Civic doesnt even require petrol !!!! Thats why Honda felt the need to fit it with a non opening filler cap.

5th November 2006, 16:56	#1 (permalink)
Dave Taylor Wheelnut Join Date: 5th September 2006 Posts: 54 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	MPG computer wrong reading Hi I have now filled my 1.8V-Tech up twice, on both occasions the Computer was telling me I was getting 41 - 42 MPG but both times I calculate 37 - 38 MPG. Which is a long way out, my wife’s Jazz is spot on. I do an 18 mile journeys to work A & B roads used to get 37 MPG from my previous 1.6 car so I was amazed when the Computer said 42 MPG. So I am disappointed twice, once because the car is less economical then it told me it was and twice because there is now something wrong with it. Has anybody checked the actual MPG against the computer reading? And what are other 1.8V-Tech owners getting regarding MPG? Regards, Dave Last edited by Dave Taylor; 6th November 2006 at 00:05.

5th November 2006, 21:15	#5 (permalink)
pcr Magic Rear Seat Join Date: 5th September 2006 Location: Shropshire Posts: 848 Thanks: 0 Thanked 1 Time in 1 Post iTrader: (0)	There's another thread where the concensous is that it reads too high, so I would assume that this is intended, for obvious reasons. Last edited by pcr; 5th November 2006 at 21:18.

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This thread is about: MPG computer wrong reading, it's in Bugs, faults and irritations at the Honda Civic forum Civinfo; Hi I have now filled my 1.8V-Tech up twice, on both occasions the Computer was telling me I was getting 41 - 42 MPG but ...

5th November 2006, 17:37	#2 (permalink)
3rd Honda Triangular Exhaust Join Date: 24th July 2006 Location: Tewkesbury Posts: 379 Thanks: 0 Thanked 4 Times in 4 Posts iTrader: (0)	I have always checked mine by 'full tank refill/miles covered' and it usually agrees within 1 mpg, though occasionally up to 2 mpg optimistic on the car's display. The tendency is for the car's display to be a bit optimistic.

5th November 2006, 18:57	#3 (permalink)
steve Valve Cap Join Date: 25th August 2006 Posts: 21 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	I have checked my 2.2 ex from new. done about 3000 miles and it usually 2 to 3 mpg optimistic on the car's display. but still getting 50mpg + so well happy.

5th November 2006, 20:56	#4 (permalink)
Billybobbo Valve Cap Join Date: 23rd April 2006 Location: North Yorkshire Posts: 15 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	Mines the same - the electronic MPG is almost always 10% over the actual mpg. At least 10% is easy to deduct in my head to get a realistic reading at a glance. Personally I think if Honda are going to bother fitting an electronic mpg meter they should at least try and get it more accurate than this, otherwise, they might as well have not bothered!

6th November 2006, 01:07	#6 (permalink)
TTDegs Super Moderator Civinfo master Join Date: 4th August 2006 Location: Cardiff Posts: 5,638 Thanks: 0 Thanked 1 Time in 1 Post iTrader: (0)	except that... Does anyone have a for sure, 100% certain answer as to which calculation using what mileometer or other method of measuring distance? We know that the speedo reads high. I don't know for certain if the mileometer therefore reads high too? We're pretty sure that the 'real time' fuel use guage is based on how much fuel is being squirted through the injectors. But I have no idea how it works out the mpg for the tank (or since reset) - but I don't think it's based on the entire distance since filling up - mine fluctuates too much for that... all of which doesn't help a great deal (sorry!), other than to say that I use my mpg display as an indication - it's not like I base my fuel buying decisions on it

6th November 2006, 08:31	#7 (permalink)
323GT-R Wheelnut Join Date: 2nd September 2006 Location: Warrington Posts: 50 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	The thing I have found with mine is that the MPG per tank reading varies quite a bit depending on how you drive immediatley after the reset - I have mine set to reset on fill up. The long term MPG, that I've now got about 6000 miles on seems to be more accurate. If you fill the car up, then drive hard immediately for a few miles, the average MPG for that tanks starts low, and never seems to recover. If you drive very gently after a fill up for a while, the MPG reads high. Typically I see about 480 - 500 miles between fill ups, best I've managed is 530 miles, worst was 440. On a 45 litre fill up, which is about where the warning comes on on my car, that's 44MPG worst, 53MPG best, 49MPG average. The long term average is now showing 49.2 MPG, so pretty much bang on over the last 6K miles. The MPG per tank has varied from 38 - 56MPG on different tanks! It must be something to do with the way it's calculated...

6th November 2006, 18:25	#8 (permalink)
4gotten Locking Wheelnut Join Date: 16th August 2006 Location: Stargard Szczecinski, Poland Posts: 111 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	I have 1.8 petrol Civic. I checked the actual MPG against the computer reading several times. I must say that computer is always to optimistic. In my case it is that the lower MPG, the bigger difference between actual and computer reading. It always varies from 2 to 5 MPG.

8th November 2006, 20:23	#11 (permalink)
bounce75 Locking Wheelnut Join Date: 26th October 2006 Posts: 128 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	My 1.8 SE has averaged 42mpg over the last 3 weeks on various journeys.

10th November 2006, 00:25	#14 (permalink)
Glasex Valve Cap Join Date: 25th September 2006 Location: Faro - Algarve - Portugal Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	Hi, when the motor is running and the car is stopped, does the MPG computer indicates any value for the instant consume??? My actual car indicates 0 MPG (SEAT IBIZA and waiting for a HONDA CIVIC 2.2 EX) ... so i believe that could be a possible reason for the difference between real and the MPG computer information ... Regards PS: Sorry for the bad english

13th November 2006, 20:44	#16 (permalink)
elbe35 Valve Cap Join Date: 28th September 2006 Location: Sunny Oldham Posts: 12 Thanks: 0 Thanked 0 Times in 0 Posts iTrader: (0)	Hi, my Civic doesnt even require petrol !!!! Thats why Honda felt the need to fit it with a non opening filler cap.