Service interval for changing spark plugs is too long

[mikebore]

I don't know what the recommended interval for spark plug changes is, but our two Jazzes (Mk1 and Mk3) have been serviced by Honda Dealers all their lives and had never had new plugs.

In the past year both cars developed slight misfiring which was completely cured by new plugs.

The Mk1 at 64,500 miles and the Mk3 at 62,400 miles.

Recommended interval should probably be around 50,000 miles on my experience.

[150234]

Your "experience" is likely to be somewhat over powered by the experience of the Honda Dealer.

They know what they're doing, just saying.

[mikebore]

Your "experience" is likely to be somewhat over powered by the experience of the Honda Dealer.

They know what they're doing, just saying.

Do they? .....not sure what you mean by being "overpowered by the experience of the Honda Dealer".

My two data points are that recommended servicing led to malfunctioning on both our cars. That shouldn't happen.

Have since found out that recommended interval is 75,000 for Iridium and 25,000 for normal. Don't know what is fitted at the factory, but clearly the Honda Dealers assume Iridium since they weren't changed at 25,000 or 50,000 on either car.

[WelshBeauty]

I don't know what the recommended interval for spark plug changes is, but our two Jazzes (Mk1 and Mk3) have been serviced by Honda Dealers all their lives and had never had new plugs.
In the past year both cars developed slight misfiring which was completely cured by new plugs.
The Mk1 at 64,500 miles and the Mk3 at 62,400 miles.
Recommended interval should probably be around 50,000 miles on my experience.

+1

[Rory]

They do fit Iridium in the factory, and, yes, the interval is 75K.

I had them changed on our 2009 car at 6yrs old, which equates to 75K on the 12.5K annual interval even though the car had only done about 30K miles.

Our 2014 car is looked after by a garage that spun out of one of the canned Honda dealers - car has done 55K and they're absolutely adamant that the plugs are good for 75K regardless of age.   Mind you, they don't seem to like doing stuff - I asked them to change the front pads and discs at the car's service a couple of weeks ago and they said they're fine for now!

[culzean]

Your "experience" is likely to be somewhat over powered by the experience of the Honda Dealer.

They know what they're doing, just saying.

Do they? .....not sure what you mean by being "overpowered by the experience of the Honda Dealer".

My two data points are that recommended servicing led to malfunctioning on both our cars. That shouldn't happen.

Have since found out that recommended interval is 75,000 for Iridium and 25,000 for normal. Don't know what is fitted at the factory, but clearly the Honda Dealers assume Iridium since they weren't changed at 25,000 or 50,000 on either car.

Any Jazz after 2008 will be fitted with Iridium plugs at factory, either NGK or Denso,  and yes they do last >75,000 miles ( it is all down to the 'erosion' of the electrodes by the spark,  and they calculate how much metal disappears per spark and then equate that to miles traveled ( if you go everywhere at 6000 revs in bottom gear the plugs may not last as long, or the engine for that matter ).  Iridium and platinum both very good with heat and spark erosion,  and the finer point in iridium electrodes makes it easier for ignition to make a spark ( lower voltage required to jump the gap, which gives coils an easier time, many coils fail on MK1 Jazz because plugs didn't get changed and gap got too big ).

[150234]

Your "experience" is likely to be somewhat over powered by the experience of the Honda Dealer.

They know what they're doing, just saying.

Do they? .....not sure what you mean by being "overpowered by the experience of the Honda Dealer".

My two data points are that recommended servicing led to malfunctioning on both our cars. That shouldn't happen.

Have since found out that recommended interval is 75,000 for Iridium and 25,000 for normal. Don't know what is fitted at the factory, but clearly the Honda Dealers assume Iridium since they weren't changed at 25,000 or 50,000 on either car.

What I mean is that whatever experience you have will be significantly less than that of a Honda dealer, quite obvious really.

They will be replaced at 75k.

[mikebore]

What I mean is that whatever experience you have will be significantly less than that of a Honda dealer, quite obvious really.

Thanks yes agreed. Certainly since no-one else has replied that theirs needed replacing before the recommended 75k, we must be unlucky with both our cars. My wife's Mk1 (5k pa) is mostly driven within 15 miles of home and my Mk3 (12k pa) is mostly used on long journeys. No 6000 rpm in bottom gear!

[madasafish]

My 2012 Jazz is on its original spark plugs at just under 50k miles. Fuel consumption is virtually unchanged since I bought it at 6 months old (the car, not me).

See no evident need to change.
Engine runs like new.
Occasional revs over 4,000 as I am a suppressed child.

[mikebore]

My 2012 Jazz is on its original spark plugs at just under 50k miles. Fuel consumption is virtually unchanged since I bought it at 6 months old (the car, not me).

See no evident need to change.
Engine runs like new.
Occasional revs over 4,000 as I am a suppressed child.

   Effect was not fuel consumption but intermittent misfires. Not continuous but enough to notice, maybe 5 or 6 times on a 200 mile trip. Good days and bad days.

Obviously the life of plugs will fit some kind of probability distribution, and we seem to have two data points near the bottom.

Neither of our cars was showing a problem at 50k.

[150234]

. No 6000 rpm in bottom gear!

You're missing out, it's actually quite punchy at higher RPM's in 1st.

[nowster]

No 6000 rpm in bottom gear!

You're missing out, it's actually quite punchy at higher RPM's in 1st.

The rev limiter kicks in about 6000 RPM. I've had a sudden loss of power from it whilst accelerating down a motorway slip road in second.

[150234]

Mine cuts out at about 6,500 rpm, always an odd feeling.

[WelshBeauty]

Mine cuts out at about 6,500 rpm, always an odd feeling.

Not sure why anyone would need to be North of 6500 revs, but anyway.

[150234]

Mine cuts out at about 6,500 rpm, always an odd feeling.

Not sure why anyone would need to be North of 6500 revs, but anyway.

What do you mean? You can't go north of 6500 anyway, but when acclerating hard stretching it out in a lower gear is a good thing to do.