Spark plug dilema

[guest7319]

Last month I  accompanied my daughter to assist in purchasing a March 2008 Honda Jazz. I have been very impressed with this vehicle with its high level of equipment and performance.
While I noticed from the service record that it has been serviced faithfully every year until 2015, the air filter was particularly clogged with dirt, so I changed it. I would think that the spark plugs would also need changed and would like to do this (couldn't believe there was 8!). So I ordered NGK plugs from eBay.
I notice from YouTube that some people remove the wiper blades and the plate below the blades to gain access to the plugs. Has anyone who has changed the eight plugs on their Jazz had to carry out this procedure or can it be done in situ, without removing anything other than the plugs?

[Jocko]

If the car is a GD then access to the plugs is okay. I think it is only the later GE which needs the panel removed.

[sparky Paul]

Just to save any confusion, when Jocko mentions GD and GE cars, he is referring to the mk.1 (2002-2008) and mk.2 (2008-2015) Jazz. The two letters identify which evolution of the car you have, and are present in the VIN number.

Most mk.1 cars are GD, but the later Chinese build mk.1 Jazz from 2006-2008 is actually GE3.

If yours is a mk.1 GE3, Jocko is correct in that you don't have to remove the scuttle trim panel to access the rear plugs, just the coil packs and wiring.

[culzean]

https://clubjazz.org/forum/index.php?topic=5437.msg33189#msg33189

Remember to follow instructions on plug packet,  screw down hand tight (not using the socket wrench,  just turn the extension by hand) and then only 1/2 to 2/3 of a turn with the wrench,  you are only trying to partially crush the sealing washer not trying to snap off the plug (it gets expensive if you do).

I have always found it best to warm the engine before trying to remove plugs as the aluminium head expands more than the steel plugs and can make the difference between struggling and fairly easy removal, also a bit nicer to have warmth from engine on a cold day.  If a plug is tight be patient and turn it backwards and forwards (the original 2 steps forward and 1 step back routine) until it gets freer.   I would do the rear plugs first as they are the hardest and most likely to be tightest to remove and do them before engine cools,  note that the coil packs for front and rear plugs are not interchangeable, so either do four at a time or lay the coil packs out on cardboard or similar as two separate groups (where you won't step on them LOL)  .

The 4 off long life Iridium plugs on MK2 and later (can be left in for at least 70K according to handbook,  but I changed mine at 60K and noticed an improvement)  have nickel plated threads on plugs to stop them bonding with the alloy,  but 'normal' plugs designed to be replaced every 25K or so have a zinc plated thread and if left in too long can get a bit sticky - and the rear plugs on MK1 are normally left in far too long.

http://www.ngk-sparkplugs.jp/english/techinfo/qa/q18/index.html

The rear plugs rarely get changed on Mk1 Jazz,  some garages don't even know they are there and even some Honda places don't seem to bother.  By the sound of your choked up air filter the 'regular servicing' didn't seem to do that much good,  I used to drive 25 to 30K a year and could have left my air filter in for more than one year (UK is not the dustiest place in the world) without it looking too black.

[olduser1]

I would add check the cabin filter located behind the glove box , often 'missed' at services and easy to swop for a new item - plenty on E Bay Amazon for Jazz models. As regards the plugs have alook through any invoices which should show the darte mileage when last replaced, allow half a day if youve not changed before.

[guest7319]

Thanks Paul, Jocko Culzean and Olduser1 for your speedy replies.

The spark plugs arrived today so if my daughters Jazz is of the type you mention, then I think I should be capable of changing them. (One of my cars from years ago was a Hillman Imp, if anyone can remember this contrary vehicle, it's when I learnt how to work on vehicles!).

Interesting about the cabin filter but something I will bear in mind. While I really like this Jazz, I feel that it may be using more fuel than it should be, so I would like to eliminate all the causes of this. It could also be that the Jazz may have a smaller tank.
I read with great interest someones link on this site, a very learned engineer's many paged article on the benefits of using eight spark plugs, (something I thought was reserved for the old V8 engines!), and I would have to agree that it may give both better performance and fuel burn. I am not sure if the new Jazz's have eight or four plugs.

The fuel filter may be another item I should look at, as these can get blocked.

The car itself has 77,000 miles on it and drives well. I would seriously consider getting one myself

Anyway friends, many thanks for all the advice and Culzean, for the detailed instruction on plug removal and replacement.

[VicW]

The Jazz is notorious for its pessimistic fuel gauging especially as it approaches empty.
This is possibly because the tank, which holds 42ltrs, is beneath the floor below the the two front seats and hence is very shallow which makes gauging very difficult using a float system.
The twin spark plug per cylinder system is used to promote better fuel mixture burn. The two plugs do not fire together but fire a few milliseconds apart.

Vic.

[culzean]

You will probably get better mpg and smoother power with new plugs as I doubt your rear ones ever been changed. 

If you think about the fuel gauge it is quite logical.  With  41 litre tank from full to half is 20.5 litres. The gauge registers empty when fuel light comes on at about 7 litres, so second 'half' of tank is only 20.5 - 7 = 13.5 litres for needle to move from half full to empty, that is why needle drops quicker on second 'half'.   Some cars like Bmw mini and Fiat 500 give less than 20 miles warning when fuel light comes on, I am rather glad that Jazz gives over 50 miles warning because quite a few country garages closed down in last 20 years or so.

 If you think jazz is expensive to fill up try my Civic with 50 litre tank -  I am relieved at cost to top tank up when driving wife's jazz.

Newer jazz have 16 valves and only 4 spark plugs,  IMHO the 8 valve twin spark Jazz 2002 to 2008 which you have is more suited to jazz than the revvy vtec lump,  the 8 valve is more tractable lower down and although it runs out of breath at about 4500 revs you don't normally go that high anyway,  the 16 valve is honestly a bit gutless below 3000.

[Jocko]

Fuel filter is in the tank. It is a real PITA to replace and you are only recommended to do so if there is a fuel pressure issue, measured at the supply rail. Fuel here in the UK is clean. Some countries, the fuel is full of detritus, and that is when the filter needs regular changing.
A blocked air filter on a fuel injected system does not lead to excess fuel consumption, as the fuel injected depends on the measured air flow. Less air flow - less petrol. It can lead to reduced performance though.

[Jem]

I have changed my spark plugs recently. I bought a spark plug socket from Halfords and it was rubbish. It undid the plugs okay but it would detach from the extension bar and level the plug and socket in the hole. I found a bit of garden pipe was best to push in the hole and grip the top of the plug.

The rear plugs are not too bad to do. You can put copperslip on the threads to help them go in and come out next time.

I think it probably took me about 2 hours to do all 8 plugs taking my time not to mess anything up.

Also if you take the plugs all out before putting the new ones in just cover the holes with something to stop and debris falling in.

[culzean]

The fuel filter may be another item I should look at, as these can get blocked.

According to Honda the fuel filter in tank is a lifetime filter, with plenty of filter area to give it a long life,   and as jocko says no need to think about it unless you are getting fuel starvation. Honda no longer use the smaller inline filters outside the tank (were usually to be found under the bonnet against bulkhead).

[guest7319]

Thanks again folks.

All these tips have been very helpful and will certainly assist me in carrying out this task. I take it that vaseline can be used instead of copperslip for putting on the plug threads?
I will also have to be careful to ensure the spark plug gap is set correctly, so will have to dig out my feeler guages!

What I really like about the Jazz handbook is that it explains in good detail how to carry out spark plug changing and other tasks, rather than the now common "should be carried out by your authorised dealer" mentality. Full marks Honda for entrusting your customers with having some technical know how.

[culzean]

Thanks again folks.

All these tips have been very helpful and will certainly assist me in carrying out this task. I take it that vaseline can be used instead of copperslip for putting on the plug threads?
I will also have to be careful to ensure the spark plug gap is set correctly, so will have to dig out my feeler guages!

What I really like about the Jazz handbook is that it explains in good detail how to carry out spark plug changing and other tasks, rather than the now common "should be carried out by your authorised dealer" mentality. Full marks Honda for entrusting your customers with having some technical know how.

I would not recommend vaseline as a substitute for copper grease - the grease bit of the copper grease disappears or dries out pretty quickly I guess just leaving copper flakes behind as the anti-corrosion lubricant, melting point of copper is about the same as steel, so copper is a proper high temperature substance . 

I have had one of these for about 12 years and still 2/3 full - much cheaper than buying small tubes    http://www.halfords.com/motoring/engine-oils-fluids/grease/halfords-copper-grease-500g

I have always found genuine NGK gaps to be spot on ( I say genuine because there are plenty of Chinese fakes around so be careful where you buy them). the last two digits of the plug number are the gap in mm,  eg. 11= 1.1mm

Attached  PDF is NGK plug spec page from their catalogue

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[Jocko]

My mechanic son-in-law just takes the plugs straight out of the packet and fits them to the vehicle. After 20 years of working with him I have never seen him with a feeler gauge in his hand!

[MartinJG]

Graphite paste is also ideal but doesn't seem to be in vogue these days. Not sure why though.