Clubjazz - Honda Jazz & HR-V Forums

Honda Jazz Forums => Honda Jazz Mk1 2002-2008 => Topic started by: guest6231 on November 26, 2016, 02:45:25 PM

Title: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6231 on November 26, 2016, 02:45:25 PM
My 2008 Jazz CVT is giving mileage of 30.5 in town and 31.5 on motorway. I bought this in July this year. It has MOT and service done by dealer in June 2016. I replaced all 4 tyres after buying it due to road noise issue. Car drives well. What can I do to improve such a poor mileage ? I live in Guildford and don't know any good independent garage nearby for Jazz.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest5079 on November 27, 2016, 02:58:48 PM
A good start is to check the air filter, a car serviced by a dealer means absolutely zilch as I found out. Their excuse is this if the owner doesn't want work done then it's not done, fair enough BUT when the car is sold as being dealer serviced as I said to them, then surely before you sell the car it is up to you to make sure all is done.
Also check the wheels after a run to make sure brakes aren't binding be careful because they can get pretty hot. Just place you hand on the centre of the wheel, they might be warm but this is normal after using brakes.  I believe that with Mk 1's if the rear spark  plugs aren't replaced this can cause problems. Good luck.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6367 on November 27, 2016, 09:02:07 PM
I have this problem also. I have sort of figure what's happening. Mine has only done 14000 miles from new 7 years ago and I have only recently bought it. Like you with a full Honda service history from a Honda dealership. Ok what I have found so far is that the car in not getting properly warm and on short journeys of only 3-4 miles I don't think the choke is going fully off.....don't forget this automatic choke and properly in the mapping. If I do short journeys I will only get 30 ish to the gallon. The cure so far I have found and it might sound daft but it works. Don't do a few miles when cold do say 5-6 miles and watch the fuel consumption improve. I have also put in RedX that all so seems to help. On a journey I did the other day of 120 miles I got 58 m.p.g. I have been in touch with Honda as the on board computer was saying I'm getting 40 m.p.g when I was really only getting 31 m.p.g Honda could not give me a answer.  Hope this help......:)
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: madasafish on November 28, 2016, 03:02:12 PM
If you are travelling under 5 miles, you will get poor fuel consumption due to the car never warming up. Worse in winter..

But check air filter first - it may be dirty.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: culzean on November 28, 2016, 05:13:45 PM
Really for the first couple of miles from cold start every car only does about 25mpg - ECU has to richen the mixture by squirting more fuel in.

Another problem with low annual mileage / short journey cars is that injectors can get well fouled up and completely mess up the ECU. Anyway IMHO before trying spark plugs and stuff it is always worth trying a crash course of Redex injection cleaner,  put 250 to 500 ml into a full tank of fuel.  It's the cheapest tune-up your car will ever get.

How many miles has car done so far in total, this will indicate if spark plugs etc may be problem.  Mk11 and onwards had iridium plugs good for about 70K,  Mk1 had normal plugs good for less than 20K
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest1372 on November 28, 2016, 06:06:35 PM
A recent poster  http://clubjazz.org/forum/index.php?topic=8621.0 (http://clubjazz.org/forum/index.php?topic=8621.0)  found their mpg had dropped considerably, but suprisingly came back again when their exhaust was replaced.  Maybe coincidence, or maybe it had got blocked with rust somehow.  A symptom they had was excess heat from the bulkhead in the area near the cupholders presumably from the exhaust/cat struggling to push the fumes out the back of the car.
--
TG
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6231 on November 28, 2016, 09:11:48 PM
Really for the first couple of miles from cold start every car only does about 25mpg - ECU has to richen the mixture by squirting more fuel in.

Another problem with low annual mileage / short journey cars is that injectors can get well fouled up and completely mess up the ECU. Anyway IMHO before trying spark plugs and stuff it is always worth trying a crash course of Redex injection cleaner,  put 250 to 500 ml into a full tank of fuel.  It's the cheapest tune-up your car will ever get.

How many miles has car done so far in total, this will indicate if spark plugs etc may be problem.  Mk11 and onwards had iridium plugs good for about 70K,  Mk1 had normal plugs good for less than 20K
Hi Culzean, thanks for your advice. Car has done 44,000 miles. On 90 mile drive also, it only gave 31.5 mpg

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Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6231 on November 28, 2016, 11:03:20 PM
It looks like spark plugs need to be changed at 24000 miles and CVT fluid at 5 years, they were never changed. Car has done 44000 miles in 8 years. Should I get them changed now ?

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Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: culzean on November 29, 2016, 07:59:53 AM
It looks like spark plugs need to be changed at 24000 miles and CVT fluid at 5 years, they were never changed. Car has done 44000 miles in 8 years. Should I get them changed now ?

I would get new plugs in at 44K,  trouble with MK1 Jazz is that not many people (including mechanics) know about rear 4 plugs and only change front 4 ones anyway.  If the gap gets too big in plugs it can stress the coil pack and cause insulation to fail,  then it gets messy.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6231 on November 29, 2016, 10:57:51 AM
It looks like spark plugs need to be changed at 24000 miles and CVT fluid at 5 years, they were never changed. Car has done 44000 miles in 8 years. Should I get them changed now ?

I would get new plugs in at 44K,  trouble with MK1 Jazz is that not many people (including mechanics) know about rear 4 plugs and only change front 4 ones anyway.  If the gap gets too big in plugs it can stress the coil pack and cause insulation to fail,  then it gets messy.
Thanks, wow there are 8 spark plugs !

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Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6231 on November 29, 2016, 02:47:36 PM
My local garage quoted me £300 for major service including spark plug, air filter, pollen filter, engine oil and CVT fluid change. Is the quote OK?

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Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6231 on November 29, 2016, 02:48:12 PM
Another question - what mileage do you get from Mk1 CVT ?

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Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: John Ratsey on November 29, 2016, 03:59:56 PM
Another question - what mileage do you get from Mk1 CVT ?
See http://clubjazz.org/forum/index.php?topic=181.0 (http://clubjazz.org/forum/index.php?topic=181.0) for a range of mpg observations.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: Denis on December 05, 2016, 09:40:49 PM
My local garage quoted me £300 for major service including spark plug, air filter, pollen filter, engine oil and CVT fluid change. Is the quote OK?

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Full service from my local retired chap who does a briliant service that you can trust. Not manufacturers parts, but sourced through the usual Europarts franchise. parts came to £96, labour charge of £40 on top..£136 for a full service is right up my street...and he changed the gearbox oil as well.
On top of this he does a good look around the vehicle and advises you of any other issues, of which there are very few!
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest4219 on December 05, 2016, 11:36:20 PM
Is it feasible that there is CVT belt slippage? Look at rpm relative to road speed. Unless I'm clogging it I don't often exceed 2000 to 2500 rpm. With mostly short shopping trips with an occasional longer trip we get about 44 mpg from our Mk1 CVT.
But we are ancient mimsers.   :'(
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest6231 on December 06, 2016, 04:39:56 PM
Now very strange mpg, this time around, I filled BP normal fuel (was doing shell normal before), and on 150 mile trip, I got mpg of 47. On shell, I was getting 32-35 on 170 miles drive, nothing else changed

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Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: culzean on December 06, 2016, 06:37:25 PM
Now very strange mpg, this time around, I filled BP normal fuel (was doing shell normal before), and on 150 mile trip, I got mpg of 47. On shell, I was getting 32-35 on 170 miles drive, nothing else changed

Car only did 44K in 8 years before you had it,  I'm guessing probably many cold starts and short trips, there is a good chance that injectors and CAT were crudded up due to low miles covered annually (and maybe even the dreaded supermarket fuel).  Now maybe with a bit of spirited driving, a few motorway miles and some decent fuel the cobwebs are being blown out and the systems are starting to work properly.

I am not a fan of low annual mileage cars,  certainly would not pay more for one as low miles are cruel on all components,  especially the engine, fuel system,  exhaust system / CAT and battery.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: John Ratsey on December 06, 2016, 07:09:54 PM
I am not a fan of low annual mileage cars,  certainly would not pay more for one as low miles are cruel on all components,  especially the engine, fuel system,  exhaust system / CAT and battery.
There is however, the diffference between the car which did frequent short trips not long enough to warm up the engine and the one which did one reasonably long trip every week or two. I would try to avoid the former but the latter should be OK. The challenge for a potential purchaser is to find out how the vehicle was used. On recent vehicles the trip computer may offer clues if it hasn't been reset as the mpg will give an indication of usage (low = short trips, high = longer trips).
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: RichardA on February 16, 2017, 08:15:59 PM
...it is always worth trying a crash course of Redex injection cleaner,  put 250 to 500 ml into a full tank of fuel.  It's the cheapest tune-up your car will ever get.

I bought a 500ml bottle of Redex from Halfords, the instructions suggest its good for four shots - is it OK to pour more than a quarter into a full tank?
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: guest334 on February 16, 2017, 11:17:35 PM
I recall putting Redex in before filling the tank but that was 30 yrs ago.
I can recommend using Shell V power and/or BP Ulimate. You may need at least 1 tank full to notice improvements.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: culzean on February 17, 2017, 01:22:39 PM
...it is always worth trying a crash course of Redex injection cleaner,  put 250 to 500 ml into a full tank of fuel.  It's the cheapest tune-up your car will ever get.

I bought a 500ml bottle of Redex from Halfords, the instructions suggest its good for four shots - is it OK to pour more than a quarter into a full tank?

As a initial 'shock and awe' treatment put at least half in,  personally I would put it all in - it wont do any harm but will help prove conclusively that it did car good or had no effect even at big dose.

Redex does really work,  it always took me a long period of tinkering and sprays etc to coax my petrol mower into life after a winter lay-up,  since using redex it starts after one or two pulls.  Same with my motorbike,  after winter lack of use it would be hard to start and then cough and splutter and not be able to tickover - again redex means that it virtually leaps into life now.  Redex is mainly Kerosene and cetane which will dissolve the lacquer and sticky stuff that Dinosaur fuel leaves behind in your system and on the injector nozzles,  the higher octane fuels certainly contain more cleaners than the cheaper ones but you get an awful lot of pretty much the same ingredients in a bottle of Redex.

LATE NOTE- started the mower today for first time since October,  started second pull - thank you redex.
Title: Re: My 2008 Jazz CVT is giving 31 mpg only
Post by: culzean on May 29, 2017, 11:34:46 AM
The power of redex,  as a very cost effective tune up you can't beat it.  The dyno does not lie............

https://www.youtube.com/watch?v=03nL8Z0dRkI (https://www.youtube.com/watch?v=03nL8Z0dRkI)