How easy is DIY for the spark plugs?

[leeharvey418]

The history of spark plugs is surprisingly long and sordid. Before platinum/iridium alloys became a thing, there were very good reasons to change your plugs every few thousand miles. I knew that things had changed, but I wanted to know what the failure mode of a bad spark plug would look like. I asked a legitimate question, and got a lot of dickish comments in response.

 

[TheMAN]

The history of spark plugs is surprisingly long and sordid. Before platinum/iridium alloys became a thing, there were very good reasons to change your plugs every few thousand miles. I knew that things had changed, but I wanted to know what the failure mode of a bad spark plug would look like. I asked a legitimate question, and got a lot of dickish comments in response.

I'm sorry, but you didn't ask specifically what you wanted to know about... you just asked why you needed to change the spark plugs as advised, and we gave you the answers... so now you tell us you were looking for something completely different than what was said, I don't think the fault lies with us, especially of the fact that you never restated your question more clearly and let this keep going on until you finally got mad at us

the "failure mode" with fancy spark plugs is not really any different than any old school spark plug... they just wear away and your ignition system just keeps working harder and harder till it kicks the can

 

[ADS-B]

The history of spark plugs is surprisingly long and sordid. Before platinum/iridium alloys became a thing, there were very good reasons to change your plugs every few thousand miles. I knew that things had changed, but I wanted to know what the failure mode of a bad spark plug would look like. I asked a legitimate question, and got a lot of dickish comments in response.

I am sorry if my comments made you feel that way. If ain't broke, don't fix it - does not quite work well with parts or components that wear and breaks over time. The manual gives us conservative recommendations. You do not have to replace the spark plugs at 75.000 miles. They may well last 100.000 miles or 150.000 miles. But when such numbers are published it means that they, Mazda guys, have done some testing, they ran the numbers and somehow they have concluded that 75.000 miles is a good time to replace the spark plug. Conservative, better safe than sorry.

 

[TheMAN]

I am sorry if my comments made you feel that way. If ain't broke, don't fix it - does not quite work well with parts or components that wear and breaks over time. The manual gives us conservative recommendations. You do not have to replace the spark plugs at 75.000 miles. They may well last 100.000 miles or 150.000 miles. But when such numbers are published it means that they, Mazda guys, have done some testing, they ran the numbers and somehow they have concluded that 75.000 miles is a good time to replace the spark plug. Conservative, better safe than sorry.

judging by my experience with our corolla's plugs, I say 100k miles is the most you should go before you start risking coil pack burn out... on some cars, coil packs fry easily, so you better be more conservative than trying to milk every mile out of the plugs

but as you said, they've done some testing and 75k probably lines up with what they've seen a lot... these engines run significantly higher compression than that corolla's, and higher compression means the ignition system as a whole has to work harder... not to mention it can possibly run hotter (definitely true with forced induction engines)... higher temperatures means the spark plugs wear even faster

I think manufactures try to draw a fine line between conservative intervals and trying to extend intervals as much as possible... people hate being inconvenienced with having to take their car to the shop all the time for routine maintenance, so that's why among many reasons, we're seeing longer and longer oil change, spark plug change, coolant change, etc intervals... but air filter intervals haven't really changed for years, because there's only so much you can do to make a filter better before it filters too good and clogs up quickly, or you make it filter less and it kills an engine faster lol

in the case of toyota's insane 120k plugs interval, I think they are expecting everyone to "drive miss daisy", so it won't wear out as quickly... I don't think so... we live in the real world lol

 

[SparkYellow]

Again - I have no drop in gas mileage, and my engine is running smoothly. By all indications, neither electrode has started to erode, as I would expect from a platinum/iridium alloy.

What’s the purpose of replacing a “wear item” that is giving no indication of having worn?

I see where you're coming from. At what interval do you remove them to check for integrity?

 

[leeharvey418]

I'm sorry, but you didn't ask specifically what you wanted to know about...

Really? Because I gave my (lack of) symptoms, and asked for a better answer. The first response I got was a screenshot of the owner’s manual. Admittedly, you did say early on that bad plugs would precipitate coil failure, but I still didn’t understand that it would happen as rapidly as it does. I figured the replacement interval was a holdover from the bad old days of distributor-driven ignition. It turns out that it’s actually more important when you have a coil on each plug. I get that now, and I have new plugs on order.

 

[TheMAN]

Really? Because I gave my (lack of) symptoms, and asked for a better answer. The first response I got was a screenshot of the owner’s manual. Admittedly, you did say early on that bad plugs would precipitate coil failure, but I still didn’t understand that it would happen as rapidly as it does. I figured the replacement interval was a holdover from the bad old days of distributor-driven ignition. It turns out that it’s actually more important when you have a coil on each plug. I get that now, and I have new plugs on order.

coil pack wear/failure is progressive, just like spark plugs (and so is many chronic diseases)... it's not "rapid", but when it does die, it either dies hard or you get phantom misfires

the maintenance schedules gets reviewed and updated all the time, and none of them are "one size fits all"... each country/region has differences due to different driving conditions, climate, and consumables supply availability

mazda corporate are the last people who'll want to screw you as an owner... they have a reputation and customer loyalty to keep... your dealer or mechanic on the other hand, are the wildcards