My 2008 Jazz CVT is giving 31 mpg only

[guest6231]

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.

[guest5079]

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.

[guest6367]

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......

[madasafish]

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.

[culzean]

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

[guest1372]

A recent poster  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

[guest6231]

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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[guest6231]

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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[culzean]

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.

[guest6231]

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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[guest6231]

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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[guest6231]

Another question - what mileage do you get from Mk1 CVT ?

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[John Ratsey]

Another question - what mileage do you get from Mk1 CVT ?

See http://clubjazz.org/forum/index.php?topic=181.0 for a range of mpg observations.

[Denis]

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!

[guest4219]

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.