How easy is DIY for the spark plugs?

[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

 

[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

EDIT: beware of fake spark plugs on btw... plenty of those on ebay and amazon... if you buy from there, buy only from known authorized dealers, such as amazon themselves... many have fallen for this scam, and ran into issues running those

 

[sm1ke]

Just a reminder here for everyone to be mindful of your tone when commenting - not only your intended tone but how it may be perceived by others. Light "jabs" are ok, but if someone is genuinely looking for answers and instead gets "jabs" from a couple of people, it puts them on the defensive, the "jabs" become distracting, and the discussion can take a turn.

In the same sense, we're all real people behind these accounts. Some of us are a little more passionate, or a bit more "vocal" than others, and it shows through in their words, and in their intention to inform or provide advice. Sometimes that's all the "jabs" are, just a bit of passion behind the words. Please try to keep that in mind everyone.

 

[sm1ke]

with cheap sockets/extensions, taping them doesn't sound like a bad idea... if you like to invest in tools, a one piece spark plug socket integrated with extension or locking extensions works way better

I remember you mentioning this in a different thread. Here's a link to that post in case anyone else is interested in seeing it.

 

[leeharvey418]

EDIT: beware of fake spark plugs on btw... plenty of those on ebay and amazon... if you buy from there, buy only from known authorized dealers, such as amazon themselves... many have fallen for this scam, and ran into issues running those

And to add to that - if a widget costs $20 from every other vendor and you find somebody selling them for $5 a piece, the person selling them for cheap is most likely trying to rip you off. The only exception would be somebody who got the wrong parts and is trying to cut their losses, and they'll most likely tell that that's what's up in the sales listing.

 

[kendel7]

And to add to that - if a widget costs $20 from every other vendor and you find somebody selling them for $5 a piece, the person selling them for cheap is most likely trying to rip you off. The only exception would be somebody who got the wrong parts and is trying to cut their losses, and they'll most likely tell that that's what's up in the sales listing.

So, if spark plugs that are purchased from auto parts stores (Advance, Auto Zone, O'Reilly's), can we assume they are genuine?

 

[HyFlyer]

So, if spark plugs that are purchased from auto parts stores (Advance, Auto Zone, O'Reilly's), can we assume they are genuine?

I'd say any of their "authorized dealers" would be a safe bet to have genuine plugs.

I've had no problems purchasing them from Walmart online but not an "authorized dealer" so

 

[leeharvey418]

I’ve never delved into what Walmart does to police vendors who sell through their site, but I do know that most of what people buy from “Walmart” online is actually coming from those third-party sellers. I’d seriously look at how much Walmart stands behind the sale before I bought any auto parts from their site.

Brick and mortar Walmart, though? Without hesitation.

 

[madar]

I'm reminded of this post years ago by member OVT about the plugs having a function as a sensor also. You might want to keep the recommended change interval.

Spark plug replacement surprise

Mazda CX-5 Service & Repair Manual - Ion Sensor - Control

 

[murky]

These came out of my 2017 CX-3 recently. They tell a story about the car which claims 40+ mpg. The burn ring is normal, I was told by strangers on the Internet, as the factory set came out the same way. Notice that only one of them has clean threads? I hand-tightened them and failed to apply force evenly. The threads seem wet/oily? It's another issue that I need to address. The NGK plugs were from O'Reilly's. While I prefer shopping at Amazon, their generous return policy means that sometimes USED items re-enter the inventory. I have received an used oil filter that was wiped clean, and ignition coils with seals broken on the boxes, both sold as new, not from Amazon Resale.

I'm not sure you can judge whether they were properly torqued by how clean the threads look. They seal on the captured crush washers, not the threads.

 

[SparkYellow]

I'm not sure you can judge whether they were properly torqued by how clean the threads look. They seal on the captured crush washers, not the threads.

You are correct. I realized that after posting but thought no one would notice.

 

[McCauleys]

Some vehicles can be quite a pain because you have to remove the intake. This is not one of those vehicles.

The only thing I'd say to watch out for is that new spark plugs feel kinda weird when you first torque them down as they usually have a crush washer. They get kinda tight but then don't immediately go tight right away like a normal clean bolt does.

 

[minnesotaart]

So, if spark plugs that are purchased from auto parts stores (Advance, Auto Zone, O'Reilly's), can we assume they are genuine?

The easiest way to tell is testing their resistance with a multimeter. Takes but a few minutes. Resistance should be 5k ohms or extremely close to that. Fake plugs will be all over the place.

 

[jadmt]

I just took about 45 minutes and changed my plugs...they looked really good at 39,000 miles...I could have probably left them in for another 10,000 or longer but once I pulled them I just went ahead and changed them. I ordered my plugs from Mazda swag so it ended up costing me $108 and 45 minutes...super easy to do and no rubber hose needed . just a 14mm spark plug socket and an extension....

 

[Mazdiod2]

I think one of the reasons plugs need to be changed is that the metal electrodes erode to the point that the gap is too large to make the electrons jump it, so no spark. Can you tell any difference in the size of the gap between the two plugs?

 

[jadmt]

I think one of the reasons plugs need to be changed is that the metal electrodes erode to the point that the gap is too large to make the electrons jump it, so no spark. Can you tell any difference in the size of the gap between the two plugs?

no difference..both would pass a .028 wire feeler gauge and neither would pass a .030 wire feeler gauge..I am guessing both would pass a .029 but don't have one of those.

 

[TheMAN]

I think it really depends on how you drive the car... mazda conservatively tells you to change at 40k because some people get boost addicted and run the engine hard lol

on a turbo engine, the more boost/harder you run the engine, the faster the spark plugs wear compared to a non-turbo as the cylinder pressures and heat are far greater

if you don't drive your car like you stole it, putt around off boost most of the time, then your spark plugs probably will last as much as the 75k miles the non-turbo recommended change interval is