Author Topic: What MPG are you getting from your Mk1 Honda Jazz ?  (Read 15042 times)

sparky Paul

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #120 on: January 05, 2018, 09:57:19 PM »
Ours dropped to mid-40s mpg last week, accompanied by a hot front right hub.

Investigation revealed nothing much,  caliper sliders free enough, some dried out brake grease around the pads, which were fairly tight.  Cleaned up, greased and refitted pads, and slipped a bit of liquid silicone behind the piston dust cover. Seems okay now, no longer binding. We'll see how it goes... hope the mpg recovers!
« Last Edit: January 05, 2018, 10:01:08 PM by sparky Paul »

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #121 on: January 05, 2018, 10:37:15 PM »
Assignable cause. Exactly what my SPC does for me!

u587162

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #122 on: January 08, 2018, 02:29:14 PM »
my 2003 jazz gets over 50mpg on motorways. Which has improved since i replaced all 8 spark plugs.


How does changing the spark plugs improve performance?  Whats the cost of replacing them?

New plugs generally improve engine response and mpg because a good spark is required for best performance and as plugs wear out the gap increases and insulator gets coated up with carbon,  which can affect spark.  New plugs also reduce the demand on the ignition coil and ensure a longer life for that, the rear plugs rarely get replaced on the 8 plug GD iDSi engine and there are cases on this and other forums of rear coils failing due to much too large a gap on worn rear electrodes.

I got my last plugs for Jazz and Civic from Opie oils,  there are a lot of Chinese copies of spark plugs around - don't go too cheap on ebay  :-X

These are standard NGK plugs...  https://www.opieoils.co.uk/pv-78126-ngk-bkr6e-11-2756-standard-spark-plug-sparkplug-projected-centre-electrode-single-plug.aspx

But plenty of compatible plugs to choose from including Bosch Iridium at a great price if you want longer life between changes  (because of their long service life iridium plugs have a smooth nickel plated thread to stop them sticking in aluminium thread of the cylinder head)

https://www.opieoils.co.uk/c-2702-lookup-results.aspx?vehicleid=4676&variantlist=79644:167787%7E167788,78126:184608%7E184609,117581:828547,214077:0,214128:1258606%7E1258607,214010:0,213981:0,213998:0&yearFilter=2004

How often do they need to be cjanged and how would you know they need changing? 

culzean

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #123 on: January 08, 2018, 03:35:10 PM »
my 2003 jazz gets over 50mpg on motorways. Which has improved since i replaced all 8 spark plugs.


How does changing the spark plugs improve performance?  Whats the cost of replacing them?

New plugs generally improve engine response and mpg because a good spark is required for best performance and as plugs wear out the gap increases and insulator gets coated up with carbon,  which can affect spark.  New plugs also reduce the demand on the ignition coil and ensure a longer life for that, the rear plugs rarely get replaced on the 8 plug GD iDSi engine and there are cases on this and other forums of rear coils failing due to much too large a gap on worn rear electrodes.

I got my last plugs for Jazz and Civic from Opie oils,  there are a lot of Chinese copies of spark plugs around - don't go too cheap on ebay  :-X

These are standard NGK plugs...  https://www.opieoils.co.uk/pv-78126-ngk-bkr6e-11-2756-standard-spark-plug-sparkplug-projected-centre-electrode-single-plug.aspx

But plenty of compatible plugs to choose from including Bosch Iridium at a great price if you want longer life between changes  (because of their long service life iridium plugs have a smooth nickel plated thread to stop them sticking in aluminium thread of the cylinder head)

https://www.opieoils.co.uk/c-2702-lookup-results.aspx?vehicleid=4676&variantlist=79644:167787%7E167788,78126:184608%7E184609,117581:828547,214077:0,214128:1258606%7E1258607,214010:0,213981:0,213998:0&yearFilter=2004

How often do they need to be changed and how would you know they need changing?

Standard plugs in i-DSi twin spark engine (8 plugs) change every 24,000 miles is recommended - Iridium type (4 plugs)  in VTEC engine (2008 -->>>) are every 70,000 miles.
 
If I had a GD that I was going to keep for a while I would be tempted to fit Iridium plugs to the rear positions and normal plugs in front - they would then be easy to change just the front 4 every 24,000 and the rear 4 every 72,000 (don't think extra 2000 miles would be a problem)..

If you don't know when plugs were changed I would change them anyway as they do affect performance and mpg.
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

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #124 on: January 08, 2018, 04:11:28 PM »
If I had a GD that I was going to keep for a while I would be tempted to fit Iridium plugs to the rear positions and normal plugs in front - they would then be easy to change just the front 4 every 24,000 and the rear 4 every 72,000
I had intended doing that. but was advised against it.

culzean

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #125 on: January 08, 2018, 04:43:35 PM »
If I had a GD that I was going to keep for a while I would be tempted to fit Iridium plugs to the rear positions and normal plugs in front - they would then be easy to change just the front 4 every 24,000 and the rear 4 every 72,000
I had intended doing that. but was advised against it.

Can't see a problem with it except up-front cost, iridium just keep the proper gap longer and give the coils an easier time because they need less voltage to give required spark.


IMHO Honda did not fit iridium originally because of extra cost.
« Last Edit: January 08, 2018, 04:46:31 PM by culzean »
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

u587162

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #126 on: January 08, 2018, 04:52:51 PM »
I bought the car (2007 reg) with 95k miles on the clock in Xmas 2016.  Spent a few hundred cleaning up the car (new exhaust, CVT flush, just changed the EGR) and did a service in Jan 2017. Wife does about 2000 to 3000 miles a year and the car came with no service history so not sure when the plugs were changed.

How much would it cost for those iridium plugs on my car if change the 4(?).

culzean

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #127 on: January 08, 2018, 05:26:14 PM »
I bought the car (2007 reg) with 95k miles on the clock in Xmas 2016.  Spent a few hundred cleaning up the car (new exhaust, CVT flush, just changed the EGR) and did a service in Jan 2017. Wife does about 2000 to 3000 miles a year and the car came with no service history so not sure when the plugs were changed.

How much would it cost for those iridium plugs on my car if change the 4(?).

If only doing low annual mileage hardly worth Iridium as normal plugs will last 8 years at 3,000 miles a year.

If you want iridium look at the lowest Opie oils link in my post that you quoted earlier.

You can get Bosch iridium for less than a fiver.
« Last Edit: January 08, 2018, 06:51:42 PM by culzean »
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

MartinJG

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #128 on: January 08, 2018, 08:41:30 PM »

I managed to get up to 49.3 on the gauge doing short mixed journeys during summer/autumn.  Now that we have moved into winter it has plummeted to 48.9 although it crept back up to 49 this week with the recent warmer spell.

Latest tank fill today. MPG down from 48.3 to 48.1 on the gauge and 42.2 real world calculation.

sparky Paul

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #129 on: January 09, 2018, 01:05:58 PM »
Sadly, I think my caliper needs further attention - it's getting warm again.  :(

The caliper, and what I could see of the piston, both look in good condition, so seal kit ordered and a full strip and rebuild is in order first... and a new flexi if that doesn't work.

Pauste9570

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #130 on: January 14, 2018, 08:25:34 PM »
42,8 (6.6l/100 km) driving mainly in the "city"... But I have very heavy foot

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #131 on: January 14, 2018, 09:46:25 PM »
A heavy foot will certainly do that to your mpg. City driving takes a lot of finesse to return good economy.

philiph

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #132 on: January 19, 2018, 08:47:06 AM »
My 2005 got an actual of 48.08 MPG.
The board computer said 55.38.
(370 miles driven)

Did anyone else have such a big difference?
What could be the reason for such a big difference?
« Last Edit: January 19, 2018, 10:33:50 AM by philiph »

Jocko

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #133 on: January 19, 2018, 09:57:01 AM »
Today I got 51.9 and the display said 53.9. Within 3.5%. Your error seems exceptionally big at over 15%.

peteo48

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Re: What MPG are you getting from your Mk1 Honda Jazz ?
« Reply #134 on: January 19, 2018, 01:54:04 PM »
I've often wondered what causes the difference between computer mpg and actual. I'm fairly consistent at the computer being 10% out (it exaggerates my mpg by 10%). This was pretty much the same on previous cars I've had including a VW Golf.

But here we have a 15% and there are drivers who record a very small percentage difference. Does driving style have anything to do with it?

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