Clubjazz - Honda Jazz & HR-V Forums
Other Hondas & General Topics => Honda & Other Honda Models => Topic started by: guest1347 on April 09, 2010, 03:54:42 PM
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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.
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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
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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
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Hi there, what car did you have before? And what was the mpg on that car?
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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.
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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 ;)
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210 miles on a full tank!
I think I'd have the emissions checked out. Something is not right there.
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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.
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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
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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
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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?
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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.
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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.
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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....
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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...
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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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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.
This sounds like the problem with the wifes Jazz. I've noticed the mpg has been poor for a while and the pads are well worn down but still legal at 30k. I drove the car back from work tonight without any heavy breaking and the front discs were too hot to touch. My wife arrived in my Golf and they were much cooler? If the brake pedal applying unwanted breaking force my problem how do I adjust the pedal to sort it out myself rather than the dealer doing it for me?
Thanks for the info.
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Not sure whether or not you still have the car but I was just reading through old posts and wanted to add what someone else had already pointed out. Have you checked the EGR valve is working properly. Having fixed mine (very easy fix), and since spoken to Honda, high fuel consumption is one of the results of a faulty valve. Worth a try
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Not sure whether or not you still have the car but I was just reading through old posts and wanted to add what someone else had already pointed out. Have you checked the EGR valve is working properly. Having fixed mine (very easy fix), and since spoken to Honda, low fuel consumption is one of the results of a faulty valve. Worth a try
I`m experiencing the same after the EGR valve replaced, better fuel consumption.
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Is it possible the engine is not warming up fully, ie a faulty thermostat?
I notice that when the blue light goes out the car still runs on a fast idle of about 1000rpm. It's another 5 minutes or so before you get the silent 750rpm. I'm guessing the blue light goes off at about 60C. That's the trouble with having a light - you don't know if its working correctly, and you can't see any trends or changes of behaviour.
I suppose you could add a temperature gauge, but these days you're probably better to get an OBDII reader instead, and see what the computer thinks it is.
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Hi All,
I need some advice.
About 4 months ago the MPG on the Jazz suddenly dropped from an average of about 45-50mpg down to barely 33mpg. I understand that the cold weather has had an impact on it as the ECU compensates with more fuel and the use of the heater etc. But I would have thought that at most this would reduce it by 5-10mpg. We've seen the dash MPG reading up to about 65mpg before, though I do take it with a pinch of salt.
I just don't understand it. There are no obvious faults with the car, all seems to be in order, we use Shell normal unleaded and it has new tyres. The only thing I can think of is that I have a carbon T1-R cold air induction filter on it. It hasn't caused any problems before and having had a look around it, nothing obvious seems to be blocking it.
Any ideas?
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Check brakes aren't binding.
After running a mile or two without stop-start road conditions, one wheel warmer to touch - on the steel or alloy face of the wheel - than the others can be a clear and EASY clue. Binding=friction=heat. Just be aware that normally both fronts will be warmer than rears since three-quarters of braking force is on the front.
Or jack and check each wheel, see if each turns freely and easily by hand.
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Thanks, I did suspect that before. As I had a seized caliper on my Civic which would roll to a stop quite abruptly but the Jazz doesn't seem to have this problem. I also changed the rear pads a month ago and there didn't appear to be a problem.
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Tyre pressure? Wheel alignment? Faulty mixture sensor? Diagnosis via an OBD machine should point you in the right direction, but it sounds like faulty combustion to me
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I would try and identify what changed around the time of the increase in fuel.
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It might even be a stiff ankle.. ;D
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Definitely not a heavy right foot since the missus does most of the driving! :)
Nothing was changed when the drop happened.
The only thing I can think of might be that the T1-R Cold Air Filter I installed a long time ago may need cleaning?
I checked the oil level last night which was fine.
Would having the heater on knock 10+mpg off your average?!?
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"Would having the heater on knock 10+mpg off your average?!?" Nope.
Clogged/very dirty air filter?
Thermostat not fully closed while engine is warming up? And so running richer for longer after cold starts.
A faulty coolant temperature sensor? It'd make it run richer, p'raps without a dash light appearing.
Bad oxygen sensor? (But a dash light would most likely appear.)
Partly clogged exhaust from a crumbling catalytic converter? (Dash light'd likely appear)
If auto gearbox... not changing all the way up to top gear?
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When you do diagnose and fix the fault, please be sure to let us know, since it would be a pointer to preventative maintenance and an easier fix.
btw: My wife is a bit heavier than me and tends to take off quite quickly in her car, so doesn't get nearly so good petrol consumption as miserly me. (She never reads the forum so I am quite safe)
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It seems to me that it is simply down to the weather and type of driving. My normal consumption is usually anything from 58 down to 45ish depending on type of driving.
Currently it is -2 degrees outside and this afternoon the average consumption reading was down to 36.3, mostly short local journeys.
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It might be the thermostat is stuck - the engine warms up enough to put the blue light out but not right up to temp. You can partly tell by the idle speed. With all electrical load off, it should idle about 750rpm. If it's not quite warmed up it will be a bit faster.
Best way is to get an OBD II code reader that also reads live engine parameters. One of them will be coolant temp. I think £50 should get you a decent one.
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The only thing I can think of is that I have a carbon T1-R cold air induction filter on it. It hasn't caused any problems before and having had a look around it, nothing obvious seems to be blocking it.
Any ideas?
The solution/cause to your problem was already mentioned, it is this definitely ;T1-R cold air induction filter.
Air induction installed requires more fuel to burn extra air coming from it, thus lowers your mpg as well
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Hello guys I am new to the forum.
I bought a 2006 1.4 Jazz sport 2 weeks ago.
The trip computer says that I am getting about 33 mpg round town. Our journeys are just short trip to and from work only about 4-5 miles.
I put £20 of petrol in and did about 120 miles before the light came on again. So I figure that its about 40mpg.
Today I reset the trip computer for a drive back on back rounds so ranging from 30 up to 60mph roads.
It registered about 45mpg which seems ok but I actually did better from my Punto that I traded in.
So how good are the trip computers should I worry that the mpg seems to be a bit high or just wait and see when the weather warms up.
Thanks guys.
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The trip computer is good to within 3 or 4 mpg, judging on tank-to-tank fills (even that's a bit variable, a slow fill or the car not level makes several litres difference to the max fill).
My usual commute is 15miles each way on country roads 40mph, which gives a trip computer reading about 50mpg, which tallies with tank-to-tank fill-ups.
I swapped cars with my wife last Nov/Dec for 8 weeks or so - and I was surprised that the consumption dropped to about 35mpg, on her 3-4mile urban trips. She is a gentle driver though tends to stick in the low gears longer than she needs.
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Like i said in my previous post, it all depends on the type of driving conditions.
With the Winter weather, my trip computer has been showing around 30-32 mpg for local driving.
On Thursday I had occasion to drive down to London, a round trip of just short of 200 miles.
Time was of the essence so I kept up with the traffic at around the legal limit (70mph)
The trip computer, on return was showing 52.6 mpg. QED.
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I figure it must be the cold weather and short journeys but as its a new car for me I just wanted to check. Also it means you have someone new on the forum ;D
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The only thing I can think of is that I have a carbon T1-R cold air induction filter on it. It hasn't caused any problems before and having had a look around it, nothing obvious seems to be blocking it.
Any ideas?
What are the benefits of this T1-R device? Thanks
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thanks to DV, I've started using fuelly.com (http://fuelly.com),really handy in tracking mpg/fuel costs
a bit frustrating to see mpg dropped down to 36 in winter from 48 in summer
city journeys + driving style contributed as well, will be getting back into savy mode now :)
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On the subject of mpg, can you beat the mpg that is customary in D on a CVT jazz by using any of the other modes eg S and 7 speed mode.
What extra mpg is likely to be incurred by using S mode to get more engine braking when approaching a junction. I still find it very unnerving how the car appears to hardly slow down when I take the foot off the acccelerator and remain in D mode when coming up to a junction.
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I have owned CVT Jazz's for the last seven years and never found the apparent lack of deceleration on a closed throttle in 'D' to be a problem.
Using 'S' mode all the time will use more fuel because the gear change-up points are higher up the rev range.
Using '7 speed ' mode is,in my opinion,a pointless exercise because all it does is make the CVT box act like a stepped change box,why Honda built it into the gearbox system only they know but it may produce stronger engine braking.
Vic.
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Perhaps Vic you have mastered the art of gentle deceleration using the brake pedal. I'm new to the Jazz and find the brakes very sharp, constantly incurring the risk of surprising the driver behind and receiving a nudge in the rear.
Hence my interest in using engine braking to slow the car when approaching a junction. I am a low mileage user and would probably easily afford afford any extra petrol consumption by dropping into S when I need to slow. Also nearest Honda dealer is 15 miles away, though I suppose any garage could change the disc pads.
There is the point too that finding the disc pads worn requires immediate attention and is more disruptive to continued motoring than using a bit of extra petrol.
Am I alone in finding the lack of deceleration on closed throttle unnerving? Did other CVT users find they had to adapt to this on switching a CVT Jazz from a manual car? I agree that the 7 speed mode seems a bit unnecessary. I can't image when I would use it if changing to S will get me the gentle engine braking I want.
Anyway I assume your answer to the question as to whether one can improve the mpg over that in D mode by using any of the other modes is 'No'.
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any automatic will be harder on the brakes than a manual box because of the lack of engine braking. Fortunately brake pads are cheaper than gearbox repairs so may be better to use the brakes than keep changing modes. The sharpest brakes I ever experienced were on a Ford Galaxy that I had to use sometimes (company pool vehicle) the brakes were literally off or on, it was a good thing the windscreen was a long way from drivers seat otherwise your head would hit it. It went back many times to the dealer but they never fixed it - apparently it was a 'characteristic' of the car.
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when my filter goes bad ! i too have noticed this .. simply changing the filter solved the problem .
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I find the 'D' 7 speed mode very useful. I use it frequently to provide engine braking when going downhill instead of (or as well as) using the brakes and when approaching junctions /traffic lights.
I had a scary incident years ago when I kept the brakes applied as I went down a long steep hill. I think the brakes nearly boiled and I was almost unable to stop at the bottom, the brakes squealed for months after this so that is why I like to use engine braking.
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I stopped using engine braking when I had my first car with decent disk brakes about 30 years ago.
The lack of engine braking on the CVT worries me not at all. Yes, Jazz brakes can be fierce but I find a gentle foot means a smoother ride.. I am used to driving autos for several decades and the Jazz auto is one of the nicer ones: early 3 speed autos were abysmal.
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Fortunately brake pads are cheaper than gearbox repairs so may be better to use the brakes than keep changing modes
How would more frequent changing of modes on a CVT model increase wear?
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changing to lower gears to increase engine braking before the box is ready to change down itself will put more energy into the gearbox, the energy of slowing the car has to go somewhere, either into the brakes as heat or to the gearbox components as ---, you guessed it as heat, - you choose. (one of the rules of thermodynamics is that all energy eventually ends up as heat).
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OK, so the CVT fluid or the components of the box may heat up, but does it follow that this will induce more wear?
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Heat eventually degrades oil characteristics meaning wear will accelerate...
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I can't for the life of me work out why my current Jazz can't get as good MPG as my last Jazz, even though they are both the same model!
Old Jazz used to easily get between 55-60mpg from motorway driving and 45-50mpg from town driving (Jazz dial mpg readout).
Old Jazz was a 2005 Sport with 110,000 on the clock. The spark plugs needed changing, the oil was almost black, it basically needed a major service service. Front two tires were on about 2.5mm, rear were on about 6mm.
It had a K&N panel filter, but I don't think that would make a massive difference on the MPG, and it had been on there for about 30,000 miles. I even managed to get 73mpg out of it, travelling from Hertfordshire to North Wales and back on a full tank, nearly 550miles :D! I always ran it on Shell VPower.
Poor Jazz got written off earlier this month :(!
New Jazz is a 2006 Sport with 70,000 on the clock. Car was getting 33mpg when I bought it, but it needed a major service and had a binding rear brake.
Car now has 4 new tyres, new oil, new oil filter, new standard air filter, new NGK spark plugs, new rear brake calliper, all brakes checked for binding and brake fluid flushed out and changed. I have been running it on VPower for 2 and half tanks now. Tyre pressures are all correct.
I am still struggling to get 50mpg or over out of the car driving on motorways, and barely got 180miles out of half a tank of fuel :(!
I can't think of anything else that could be affecting the MPG. I really don't think its the K&N filter on the old car, especially since I hadn't cleaned it out for 30k! And especially since the old one desperately needed a service and still got me 73mpg!
Can anyone think of anything else that I might have missed?
Cheeers!
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Hi i think is the weather and winter which are giving bad mpg i noticed with my Jazz in summer i was getting 55 mpg now is winter i get 50/51mpg and the only thing i chaanged was fitting 2 new falknes.
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Hi i think is the weather and winter which are giving bad mpg i noticed with my Jazz in summer i was getting 55 mpg now is winter i get 50/51mpg and the only thing i chaanged was fitting 2 new falknes.
Has the weather really changed that much in 4 weeks that would make the difference between an older/higher milage car that badly needed a service getting higher MPG in late October than a car thats just had a major service with everything changed in November? I never remember the cold really affecting my MPG that much the last two winters, maybe 2 or 3mpg!
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The cold weather would make up to 10% change in fuel consumption.
Check if the water temperature sensor wire has not got any resistor built in (the engine controller would think it`s even colder outside so more fuel would be injected for better performance = cheap tuning).
Is there any oil consumption? Checked tappets?
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Hi There,
In the winter my 04 drops from 43mpg to around 34 mpg on local journeys in the hills of West Yorkshire.
My wife in a 57 who only does short local journeys i.e. school runs drops from around 39mpg to around 31mpg.
Cold engines and cold air through the intakes drops it terrably as does putting the heater n (hardly use the A/C in the Summer).
Regards,
Andrew
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I agree the cold weather affects the MPG, but the weather isn't winter cold yet. Its been 8-10 degrees at night and hasn't dropped below 0 degrees yet, still yet to get ice on my car!
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First suspect is always brakes binding even a tiny bit. I was surprised when I changed the front discs/pads on mine to get several mpg improvement. Just take the pads out, clean them up and put them back.
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On cleaning pads, when I had a VW, there was always an item on the service invoice for brake cleaner and I was told that they routinely cleaned the brakes. (whether they did or not I'll never know).
The other thing with the VW was the brake pads lasted at least 3 or 4 times as long as Honda ones do. This makes me think that Honda pads are made of a softer material and possibly the dust generated causes the brakes to bind?
Just a theory but the brake binding issue seems to crop up quite a lot on this site but also civinfo.com
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My fuel consumption -over the same journey and routes ahs dropped 8% in the last 3 weeks with colder weather. Happens every year.
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Hello
I have Honda Jazz SE sports 2003, 1.4 engine. I have noticed a significant drop in fuel efficiency from 39miles/gallon to 32.5 miles/gallon . There is no improvement even after full service last week including oil and filter changes and wheel alignment.Also, I get the car serviced every year. Either it could be because of poor car service or something else. Six months back, one of the main part of exhaust was replaced since it was quite corroded and wondering if it could have made a difference. Please advice.
Thanks
PK
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It's winter
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Winter...
http://www.theaa.com/motoring_advice/news/aa-fuel-for-thought-increased-cost-of-winter-motoring.html
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It is winter my mpg dropped from 56 mpg in summer to 47.5 mpg in winter
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Yep winter plays a big part in reducing mpg. Firstly air temp is lower so more oxygen so more fuel is needed, secondly you use your wipers, heaters and headlights more and also oil and cat takes longer to reach operating temp when it is most efficient. If you use winter tyres, their rolling resistance is higher, so less fuel efficient and finally drivers are more cautious in the winter and I find are generally much slower around town when its wet, so I tend to get stuck in traffic/at traffic lights for longer than usual.
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Hi,
Both I and my wife have Jazz's, 04 and 57 respectively and both of us experiencs massive drops in efficiency during the winter months. I would guess that it drops by around 20%.
Still love the cars though.
Regards,
Andrew
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Thanks everyone !
Yes, I thought about that however, 38 miles/gallon is the minimum efficiency I have noticed. I remember whole last winter, the efficiency didn't drip below 38 mpg. Also,I have this issue for last three months when it was Autumn and not much cold too. I spoke about this to the guy who serviced my car( F1 Autocentres) and he recommended a fuel treatment that cleans up engine etc though I am not sure its worth trying?
Many thanks
PK
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I spoke about this to the guy who serviced my car( F1 Autocentres) and he recommended a fuel treatment that cleans up engine etc though I am not sure its worth trying?
Many thanks
PK
I`d use premium fuel 2-3 times, it has all the treatment additives already in it...
When was your all 8 spark plugs last replaced?
You must run short distances to get below 40mpg... I cannot go below 43mpg by gentle driving in winter.
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I spoke about this to the guy who serviced my car( F1 Autocentres) and he recommended a fuel treatment that cleans up engine etc though I am not sure its worth trying?
Many thanks
PK
First off I would try Redex rather than premium fuel, a 500ml bottle to treat 4 tanks will set you back about £8 - because it is the first clean for a while ignore the advice about dosage and just tip half bottle in first tank and then follow up with half the rest into next tank, and empty bottle into third tank. It's almost impossible to overdose with Redex. After initial clean I would use premium fuel every 2nd or 3rd tank to keep everything in good shape.
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I have tried Redex and premium fuels. None has made any measurable difference. I keep accurate records.
Redex worked well in the days of low quality fuels and incomplete combustion due to the use of carburetors/manual chokes/ early fuel injection. But today's fuel injection systems measure very accurately, cars can run well over 100,000 miles without having to decarbonise the cylinder head and parts like injectors are made to very fine tolerances.
In my view , a waste of time and money.
If your car has levels of dirt and carbon due to the use of EGR valves, a clean of the EGR valve and air intake and throttle body are far more effective. And also any air sensors in the air intake -they end up being covered in a layer of fine dirt.
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Could it be a seized caliper perhaps?
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[quote Could it be a seized caliper perhaps?[/quote]
Really worth checking out.
Short of jacking the car and spinning each wheel by hand to check if one/two of them is 'sticky', feel the alloy/steel of each wheel by hand after a steady run of a couple of miles. If one of the wheels is warmer than others, friction from a binding caliper is likely heating it up.
NB:Front wheels will often feel (evenly) warmer than rears because the fronts account for 75% braking.
Getting the wheels off the ground is the best (most definitive) way, however I've used the alternative outlined above successfully a couple of times in the past.
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[quote Could it be a seized caliper perhaps?
Really worth checking out.
Short of jacking the car and spinning each wheel by hand to check if one/two of them is 'sticky', feel the alloy/steel of each wheel by hand after a steady run of a couple of miles. If one of the wheels is warmer than others, friction from a binding caliper is likely heating it up.
NB:Front wheels will often feel (evenly) warmer than rears because the fronts account for 75% braking.
Getting the wheels off the ground is the best (most definitive) way, however I've used the alternative outlined above successfully a couple of times in the past.
[/quote]
We have a 2005 1.4 cvt and recently, last month or so, fuel consumption has gone from @53 mpg going down to @44 mpg. I do live in the foothills of the pyrenees, so quite hilly. I thought that the lose of mpg was a combination cooler weather and different journeys. But Thursday last week smelt the rear nearside brake was binding confirmed by a very warm alloy wheel.
Well worth checking.
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GD has MAP (Manifold Absolute Pressure), and IAT (Intake Air Temperature) sensors, together these do the same job as MAF (mass Air Flow) sensor would.
Lambda (oxygen sensor) in exhaust can also affect fuel consumption if it goes faulty because it misreads the exhaust gases and can tell ECU to squirt more petrol in.
if EGR is stuck open you would notice bad running at low revs. If it is stuck closed you may never notice, but it would slightly reduce MPG at higher revs, and engine may run slightly hotter (EGR allows exhaust gas into inlet manifold at higher revs to cool the combustion and reduce NOx emissions). .
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Thanks everyone, it seems like I would be able improve fuel efficiency by addressing suggested causes. I will look into the service history and see when spark plugs were replaced. Is it good to get them replaced periodically? I had a full service recently and plugs got cleaned, I think.
To be honest, I have had been filling fuel from an independent petrol station as its cheap and may not have much additives. I will try Premium Petrol /Redex and it may help.
I have serious doubt regarding the binding caliper or something due to wheel. I have noticed little stickiness while driving .It may sound stupid, but wonder if I should test for sticky wheel while driving or just by spinning wheels in resting car. I will check after a short drive for any hotter wheel. About 3 months back, left side front tyre ran over a big deep crack on a A road at the speed of about 50mph.My car survived but other got flat tyres. Though, nothing serious came up in servicing this month. Alignment was out by 3mm and they fixed it.
Secondly, main part of exhaust was changed last year and wondering if Lambda got affected. Could you please suggest how to check that?
Also how to check EGR and air sensor/valve issue? Though, I presume there may not be obvious symptoms to identify Exhaust and EGR related issues.
Oh yes, my car does stalls sometimes and a mechanic said it may be coz it needs more gas. I thought its worth mentioning here as it may hint towards one of the suggested reasons.
Thanks again!
PK
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I can vouch for the good effects of a cleaned EGR valve.
HTH,
Stefano
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I have an answer that might be useful to some people experiencing very poor fuel economy with a Honda Jazz.
Our Honda Jazz was first registered in July 2004. We bought it second-hand five years ago.
This year the fuel economy started dropping from its original 5.7L/100km to a disastrous average of 7.0 this month (August 2019).
We live in a Mediterranean climate, which is typically hot and dusty all summer, with very little rain, so this was not a cold running problem. Initially, I attributed the heavy consumption to my wife's poor driving (she has no idea what gear she's in most of the time). I also thought that the airconditioning system might be affecting consumption (but not as much as this!) I did check tyre pressures.
However, I noticed a distinct lack of power at low RPM on familiar, steep, uphill stretches to the point where I was definitely having to use a lower gear than previously. Switching off the aircon made no difference.
Initially, my bet was on a faulty oxygen sensor or lack of power to its heater. I'm glad I didn't put money on that because my mechanic traced the problem to a BUILD UP OF DIRT INSIDE THE THROTTLE CHAMBER. He removed this, cleaned it thoroughly, and the average consumption is now down to 5.2 litres per 100km! (I think that's well over 50mpg.) Update: today the average is 5.5 with shorter journeys and I expect it will rise to the original 5.7 over the next week of "typical" driving. (It's very mountainous here.)
I believe that this dismantling and cleaning is a fairly easy DIY job so it's worth doing if you, too, drive in a dusty climate or through, say, a dusty car park each day.
My mechanic said that a faulty ignition coil can also cause poor fuel economy, but that wasn't the problem this time. (The engine has two spark plugs per cylinder. If one isn't working, it's not obvious but it will affect performance.) He also said that on high-mileage engines, the exhaust & inlet valves can cause poor fuel consumption. (They are adjusted automatically, hydraulically. In cold weather, you'll often hear one or two tapping until the engine warms up. If the tapping continues when hot, you've got a problem.)
I note, too, that others say the AGR valve might need to be cleaned.
I hope this info. helps someone else!
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They are adjusted automatically, hydraulically.
They are not adjusted automatically. The setting is part of regular servicing. They will tick when cold, but as the valve stems heat up and expand the should quieten down. If they don't then the clearance is too great (possibly only one valve), and should be adjusted.
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My (professional) car mechanic assures me that they are set by hydraulic pressure. There is no manual adjustment on my (2004) 1.4L model. Forgive me if I choose to believe him.
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Fine by me.
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They are adjusted automatically, hydraulically.
They are not adjusted automatically. The setting is part of regular servicing. They will tick when cold, but as the valve stems heat up and expand the should quieten down. If they don't then the clearance is too great (possibly only one valve), and should be adjusted.
+1. no hydraulic adjustment on Honda tappets they are fixed by adjusting screws on tappet arms. Strange thing is that the tappet gap on my motorbike is actually larger when hot than when cold, this is caused by the aluminium of the cylinder head expanding more than the valve stem and moving the tappet pivot away from the top of valve stems.
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My (professional) car mechanic assures me that they are set by hydraulic pressure. There is no manual adjustment on my (2004) 1.4L model. Forgive me if I choose to believe him.
You can believe him if you wish, but he's quite wrong.
No hydraulic tappets on the I-DSi engine, as Culzean says, they are manual adjusters on the rocker arms.
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Item 7 on attached photo.
https://www.parts-honda.uk/honda-cars/JAZZ/2004/14-S/ENGINE/VALVE-ROCKER-ARM/17SAA401/E__1200/1/21683 (https://www.parts-honda.uk/honda-cars/JAZZ/2004/14-S/ENGINE/VALVE-ROCKER-ARM/17SAA401/E__1200/1/21683)
(https://www.parts-honda.uk/thumbs/honda_cars/auto/17SAA401/IMGE/930_930/VALVE-ROCKER-ARM-Honda-Cars-JAZZ-2004-14-S-5-speed-manual-E__1200.jpg)
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I have never ever had issues due to dirt build up in inlet manifolds of petrol cars. It's usually a sign of poor maintenance- dirty oil ,dirty filters and excessive oil mist injected into the manifold..Over a period of years..
If it was a diesel with an EGR.. then possibly due to lots of shoirt journeys..