Author Topic: Poor fuel economy? *Please read this!* (the *definitive* poor fuel economy topic)  (Read 53814 times)

guest1347

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I have done a few calculations over the past weeks, & it would appear my 54 plate DSI-SE (1.4) is giving me between 39-41 mpg, although the onboard calculator gives readings up to 50.3 mpg. The car has done 51,ooo miles & has all the usual faults--rear bearings, parking brake, noisy clutch release bearing etc. Any ideas on the poor mpg would be appreciated.

Note by Admin:
Because there are numerous topics in the forums on poor fuel economy and all come to the same basic conclusion, all have been merged into one large topic. Normally poor economy is down to driving style, cold temperatures or short trips.

Please remember - your Jazz will probably not return the official mpg figures quoted in the brochures! They are calculated in a laboratory and are not reflective of real-world driving! This is true regardless of make or model.

olduser1

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Change the air filter, then fill the tank cover 300 miles mixed driving then refill.
Check the consumption - the fuel read out is always optimistic -  its agude.
I used Shell is all my Jazz vehicles and averaged around 48mpg over 120k

guest1767

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Hi Everyone,

I'm new to this forum and new to owning a Honda Jazz its only been a month since i brought it, I apologies if this topic has been covered but after a search I didn't find the answer I was looking for.

I have a Honda Jazz 1.4 i-DSI, manual 52 Reg with 44k on the clock, full service history, I had the car fully service a few weeks ago, I over looked the work while the guy at the garage was servicing it. The garage advised me that I needed 8 spark plugs for the car so all of them along with a branded pollen filter, branded air filter,branded oil filter and top brand oil was all changed.

I have put brand NEW MICHELIN TYRES on they car all correct tyre pressure 30 psi and the back and 32 psi at the front but the MPG is still 25MPG on the trip meter, I have hit 30MPG on a round trip on highways but never get the type of MPG other members are stating, I read all the reviews on the net and all said it would do are 35/40 MPG inner city driving but I have never seen that.

I always keep to the speed limit, don't brake or accelerate hard, I don't have A/C on, the car does short and long range travel, I always fill up at Shell, but I am getting around 210 miles to a full tank which costs around £45.My boot is empty apart from the spare wheel which is a space saver that you get with the car. I really do not know what to do, I really thought that car needed a good service but that didn't work.

Does anyone have any ideas on what I can do to improve the MPG? I know the is a problem with the car but I don't know what it is, I have searched all off the internet but not come across a solution.

Thank you in advance for your replies.

Regards

HondJazzUK52

edit by Admin 28 Nov 2010 - removed bold text

RichardA

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Hi there, what car did you have before? And what was the mpg on that car?

guest1521

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In addition to RichardA's query I would add:
I have a GE model Jazz - later than yours - and I find the mpg to be every bit as I'd hoped for, pleasingly so. The GE i-vTEC was designed for very similar mpg to your model.

I presume you drive following sensible fuel economy principles such as always being in as high a gear as possible and that you shift up through the gears as early as your speed and road conditions allow (while not 'lugging' the engine). My i-vTEC engine will 'pull' or 'tootle along' happily on the flat - though, admittedly, with not a great deal of vigor - from as low as 1100/1200 rpm in top gear; your i-DSI engine is reputed to be even better in that respect. Better torque characteristics... even more tractable.

I presume also that you do not habitually drive with a foot resting even with the lightest of touch on the brake pedal.

With those possibly insultingly unhelpful (sorry!) suggestions out of the way... here's a thought - though it should possibly have been picked up at service and/or when your new Michelins were fitted. I wonder if one (or more) of your brakes is 'dragging'... slightly seized on. If one (or more) of your wheels feels unduly warm to the touch after driving even a short distance that'll be a great clue. Go round them all and feel them in turn. If you have another car in the household, compare them. Of course the definitive way to check it out is to jack the car up and spin each wheel by hand. Having found one wheel that is 'sticky' to turn, don't presume it is the only culprit. It could be that the brake mechanism needs servicing/lubrication so it'll work freely. All the best.       

guest765

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Honda jazz UK 52
Are you zeroing the ave mpg on the dashboard after you fill up ?
Unless you reset the coords it will give you a continuous read out .....zero all settings, trip ect then fill up and runit see what AVE/ MPG reads out ;)

Geoffers

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210 miles on a full tank!
I think I'd have the emissions checked out. Something is not right there.

culzean

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There is no way that you should be only getting 25 to 30 mpg with a 1.4 GD.

The engine should pull sweetly under load from low revs, from say 10 to 15 mph in 3rd gear, if it splutters or hunts suspect the EGR valve.

Have you zeroed the trip mileage (this will also zero the average mpg readout), I do this every time I fill up and you will find that the average mpg readout is very responsive to driving style to start with, but because it is an average readout it becomes more 'fixed' as you get 100 miles or more on the trip.

You could take out one of the front spark plugs and check the colour of the electrode and insulation, it should be light coloured, either straw or light grey, if it is dark brown or black your mixture is way to rich.

If all the above are OK you will have to put it into a garage for a proper check-up.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

olduser1

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These days low MPG is generally down to the poor weather conditions and or the large application of R foot, take is slow and get the vehicle warmed up.
Check or ask someone to inspect the ait filter if OK check the mpg fill to fill = after 250 miles

guest1767

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Hi Guys,

I am still getting bad MPG, about 29.2MPG reading on the meter, I have checked the brakes and there not sticking, I used D-Tox fuel system cleaner which was recommend on one of the thread on this forum when I went to fill up, I put the D-TOX cleaner in the tank and then filled up at Shell (Full Tank) zeroed the trip meter also MPG meter and to my surprise when i drove of I was getting 60 + MPG and while I was driving it became a constant 45 MPG, I parked up outside my house thinking "great the problems solved" but the next day I started the car and went around driving my MPG dropped again to 29.2 MPG and is not moving up, for people to understand how I drive I was constantly getting 40-45MPG on my previous HONDA 1.4 Civic.

Can anyone help??

New tyres, fully service (all 8 spark plugs changed).

Can I ask what tyre pressure you guys are using on your car, its usually me and my wife in the car.

I really do think I have a problem with this car, I brought the car near the end of summer and was still getting the around 31MPG town driving but I have read on this forum and other forums that people are constantly getting around 38-45MPG local town driving.

Thank you for your replies in advance.


Regards

Geoffers

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Is somebody stealing your fuel?
Unlikely I know, but there has to be a reason for your apparent low mpg!

Are you sure you are not losing fuel?

guest1521

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I think you indicated in an earlier post that you are getting around just 210 miles per tank. That would suggest that your computer is certainly not playing up, you'd think... wouldn't you??? Your tyre pressures are OK - would have to be very underinflated for the low mpg you are reporting.

An earlier poster suggested removing a spark plug to check if it's NOT sooty black which would suggest 'rich' running. Should be 'clean grey/light tan' in appearance after at least a short run so that the engine is up to normal running temperature. An exhaust emissions check might be revealing.
----- Double Post Prevention - new post below: 1292196030 -----
Tyres... You mentioned in your first post that you have fitted new tyres. If the old ones were unevenly worn (inner or outer edges unduly worn) I presume you would have had your tracking checked/adjusted on fitting the new ones. Tracking considerably out of correct alignment not only causes tyres to wear faster and unevenly but also the resultant 'drag' can use more fuel.

bill888

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I always fill up at Shell, but I am getting around 210 miles to a full tank which costs around £45.

You haven't mentioned which part of the country you are located, but if you have not already tried it, can I suggest you switch to a different brand of petrol and see if it makes a difference.

TicFan recently reported poor fuel economy when using Shell Fuelsave by as much as 10mpg difference.
http://clubjazz.org/forum/jazz-gd-2002-2008/mpg-could-not-believe-it/

fwiw, I tend to alternate between Shell and Sainsburys (I tend to stay clear of Tesco and Asda) and I've not noticed any poor MPG issues with Shell fuelsave, yet....
« Last Edit: December 13, 2010, 06:50:16 AM by bill888 »
2007(57) Jazz 1.4SE CVT-7 (GE3 - made in China)

guest1809

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I've bought my Jazz 1.4 (2005 -105000 km = 62000 miles) 2 weeks ago. Since i live in belgium previous (first owner) is obligatoire to go to a "techical chec-up" before the sale. This techinical checkup is done by a state owned company and among others they check the emmission before the sale...so the car has been tested on the 60 different points and all of them were ok...however i have the same problem, it does 28 MPG while it has been perfectly maintained (have a maintenance book)...i never drive it fast and high in the revs when its cold, tire pressure i 2.3 bar and still i get 28 MPG...i was thinking of getting the tappets adjusted and i new sparkplugs but i wonder if this will change anything...BTW here in belgium they do not adjust the tappets until the 120000km or 72000 miles.

So my friend you are not the only one with the very thirsty jazz :(...

For the rest it's a great car...

guest1336

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I do not think tyres or fuel type can cause this bad fuel consumption. You can check if you have a brake depress offset by feeling the temperature of all your rims when stopping after a drive - it should all be at the same temperature and relatively cold. When the brake pedal is not properly adjusted and a slight break command is sensed, one or more wheels may continuously have a slight brake effect while driving (hardly noticeable), causing heat and the rim to heat up. This is the easy try-yourself stuff.
Most probably it is a sensor that is used by the engine management system (computer box) that has failed, giving wrong information (eg temperature, vacuum etc) and resulting in wrong fuel/air mixture.
If for example all inlet valves (VTEC engine) kick in on footdown, fuel consumption is bad. One observes this by the much louder engine noise. If this trigger point is not correct it will result in poor fuel consumption.
My advice is to have the car tested at a Honda dealer on their electronic diagnostic test system to locate the fault. The sooner this is done, the sooner you will save on fuel.

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