Coil Pack Replacements

[burkey]

Hello Guys,

I just passed my driving license Wednesday last week and brought a 2007 Honda Jazz 1.2 iDsi with 138K on the clock.

After having a friend of mine look over the mechanicals of the car it seems i have brought a solid car, done a few hundred miles in her so far and everything seems to be fine.

I noticed that after driving it, the engine management light came on, so i used a friends ODB reader to get the codes, it was a cylinder 1 and 4 misfire, he advised to swap out the coil packs to cylinder 2 and 3 and see if the issue reoccurs, which it sort of has, the engine light will come on very occasionally.

It would seem I have 2 dying coil packs and would like to replace them, I would preferably like to replace with the factory Hitachi coil packs rather than after market. I cannot seem to find anywhere that sells them, I have found lots of aftermarket ones and second hand ones on ebay but don't mind spending the few extra pounds on new OEM ones for piece of mind.

I would like to know where people would suggest getting them from, Eurocar parts don't seem to stock them either and a general google search doesnt seem to find the Hitachi OEM parts.

Any and all advice would be appreciated.

Regards

Burkey

[marcel]

Have you tried the Honda agents?

[Jocko]

Welcome. I would change all eight plugs first. For coil packs/plug tops I would try here:
https://www.parts-honda.uk/

[JazzyB]

I would use NGK ones which like their plugs are excellent

[burkey]

Thanks for the suggestions peeps.

All the spark plugs were replaced a very short time ago when I took them out they were in excellent condition.

Spark gap was spot on too

I will check out Honda parts and if no luck I will speak to a Honda dealer

[Jocko]

As an owner of an old, higher mileage Jazz I wouldn't be too fussy as to which coil packs I bought, but there again, I'm just a tight Scotsman.

[burkey]

Hey guys,

A little update on this, after swapping around the coil pack on the top of the engine ainhave just ran another set of odb readings.

I swapped cylinder 1 and 4 coil to cylinder 2 and 3, the new odb readings show that cylinder 1 and 4 are still misfiring and now it’s showing cylinder 2 is misfiring.

I spoke to a Honda mechanic and he said it is very very unlikely for the front/top set of plugs to fail however the rear/bottom set are much more likely to fail.

I think the problem lies with the rear set of coils, the friend who has been helping me advised pulling out the rear coils and check the plugs before swapping out and of the coils  it was obvious the front set of plugs had been changed.

The rear coils are a different shape to the front therefore I don’t wish to buy the wrong ones as they would not be interchangeable.

Any and all advice would be gratefully received

[culzean]

The rear spark coils get a harder time than the front because the rear plugs don't get changed and the electrode gap gets bigger, this causes the coils to have to generate a higher voltage to jump the gap, which stresses the electrical insulation, the other thing is the exhaust manifold is at the rear making lots of heat.

The front plugs normally get changed regularly and run cooler anyway.

The way the coils work is that there are two coils of copper wire around a metal core, the primary ( 12 volt side ) takes about 5 amps,  when the voltage is applied to primary it charges up the metal core with magnetic energy, if you then cut off the power ( this is what the mechanical can operated points used to do in the old system before higher voltage transistors were developed )  and don't give the magnetic energy a path to discharge the energy it will discharge through the secondary ( high voltage side ) and as the magnetic field collapses it will force the voltage to rise until it is high enough to spark over the plug gap,  but as the plugs get older and gap wears ( spark erodes metal off the plug electrodes ) the 'spark over' voltage needs to be higher and higher to spark over the gap, this causes electrical insulation to fail. 

You can leave the 12 volts on the coil for ever and you won't get a spark ( but the coil will get hot ), the spark happens when you remove the 12 volts by ' open circuiting' the primary coil, then the magnetic field collapses and generates voltage that looks for a way to escape / discharge, the bigger the gap the higher the voltage has to get.

 There is data that gives the wear rate of plug gap per 1000 miles, Iridium is much harder than the normal spark plug electrodes and the sparks do not erode it anywhere near as fast.

https://auto.howstuffworks.com/under-the-hood/car-part-longevity/automotive-spark-plugs-last.htm

[springswood]

I seemed to recall Hitachi coil packs can be found on eBay. I checked. Good news is they are, bad news, new rear ones are £70+ each, s/h about £20.

[Jazzmeister]

Can the coil packs on these engines be replaced individually or only as a set of 8?

[culzean]

Just replace the failed one - no need to do any more than that...

[Jazzmeister]

Just replace the failed one - no need to do any more than that...

Thanks I thought as much, when googling it it seems that if you take it to Honda they want to replace all 8 coils if they find one being faulty, with original Honda parts and dealer labour that would cost a fortune!