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I changed mine in June at 3 years and 780 miles after the car had been in long-term storage. The plugs came out without issue, but I’m not sure I would push it — 2 year plug changes are cheap insurance.
One curiosity, the passenger front plug looked brand new, as if it wasn’t getting spark. I didn’t notice a misfire and when I sent the oil sample in for analysis, they didn’t find large amounts of fuel in the oil. My initial thought is that it’s a bad coil, so I picked up an extra but I haven’t had time to pull the new plug and see if it’s as clean as the old 780 mile one that was pulled out.
I have been going cross-eyed looking at images of spark-plugs and learning how to analyze them - not actually for my GT3, but for another car which is quite old and has some running issues.
I think your no.6 plug looks brand-new, simply because you only had covered only 780 miles and these engines run quite lean.
If your coil was failing, the plug would look anything but new, it would look fuel-fouled and it doesn't.
I am new to this, so could well be wrong in my analysis.
So I'm curious... if your spark old plugs look brand spankin' new when your're replacing them... is there really any value at all in replacing them so often??
I mean... it blew my mind when I was told they should be replaced every 2 years but hey... the cars are driven hard (or should be) and there seems to be consensus that this really isn't complete lunacy... so I'm sold. But for a car that's not driven hard... or is barely driven at all... what's being accomplished here? Spark plugs don't degrade over time even without use like tires do right? And even if they did... I'd expect that to come into play after a decade rather than after a couple years since most normal cars have their spark plug intervals MASSIVELY farther apart.
You’re point is valid — they likely don’t need to be changed that often in some conditions. If I were taking my cars to the dealer, I would probably think twice (for sake of price/value & time). That said, I know how to wrench, I have space and the tools so it’s extremely cheap insurance to keep up with the maintenance. I also have a healthy fear of dealing with a stuck plug. Never again.
Now… sometimes I let my brake fluid go a little longer than the recommended 2-year changes if it shows less than 2% water content, but don’t tell anybody!
So I'm curious... if your spark old plugs look brand spankin' new when your're replacing them... is there really any value at all in replacing them so often??
I mean... it blew my mind when I was told they should be replaced every 2 years but hey... the cars are driven hard (or should be) and there seems to be consensus that this really isn't complete lunacy... so I'm sold. But for a car that's not driven hard... or is barely driven at all... what's being accomplished here? Spark plugs don't degrade over time even without use like tires do right? And even if they did... I'd expect that to come into play after a decade rather than after a couple years since most normal cars have their spark plug intervals MASSIVELY farther apart.
Have you seen the spark plug photos posted by Trakcar? The electrodes were totally worn away (before scheduled change). So, it’s not a given that they look or perform like new…
And he and others had rough running that was fixed with new plugs.
So I'm curious... if your spark old plugs look brand spankin' new when your're replacing them... is there really any value at all in replacing them so often??
I mean... it blew my mind when I was told they should be replaced every 2 years but hey... the cars are driven hard (or should be) and there seems to be consensus that this really isn't complete lunacy... so I'm sold. But for a car that's not driven hard... or is barely driven at all... what's being accomplished here? Spark plugs don't degrade over time even without use like tires do right? And even if they did... I'd expect that to come into play after a decade rather than after a couple years since most normal cars have their spark plug intervals MASSIVELY farther apart.
Given that it's an exceptionally easy DIY and relatively inexpensive parts, I don't see the harm in the two year interval.
But yeah, for a car that's driven easy in a casual fashion, it's a little aggressive.
Spark plug performance is dictated by:
1. Correct gap
2. Clean cathode and anode surfaces, free of any build-up
3. Sharp/square edges on both anode and cathode (sparks jump from an edge, not a flat or rounded surface)
4. Uncompromised porcelain insulation - old plug leads (or coil boots) can deteriorate, this encourages arcing through the porcelain, which then degrades the porcelain (looks like jagged brown hairline pitting)
5. Plugs often have a RF suppression resistor in-line with the central electrode - this must not have degraded/become high impedance
If the plugs are not fouled and the edges are all sharp, they’re likely to be just fine. If there is no fouling, but the edges are rounded over, these can be filed square again (but absolutely zero debris must remain upon reinstallation).
Have you seen the spark plug photos posted by Trakcar? The electrodes were totally worn away (before scheduled change). So, it’s not a given that they look or perform like new…
And he and others had rough running that was fixed with new plugs.
Yeah. As I mentioned, I'm already sold on doing it for cars that get driven hard.
Originally Posted by 997gr8
Spark plug performance is dictated by:
If there is no fouling, but the edges are rounded over, these can be filed square again
That can't possibly apply here, right? Since these plugs can't be gapped, I have to assume that any tangible amount of filing would ruin the set gap.
Yeah. As I mentioned, I'm already sold on doing it for cars that get driven hard.
That can't possibly apply here, right? Since these plugs can't be gapped, I have to assume that any tangible amount of filing would ruin the set gap.
I would guess you are correct, but it’s a moot point, as if you can afford a GT3, hopefully, you’re not trying to re-use old plugs by filing and re-gapping, and more importantly, running the risk of debris in your engine.
On single strap plugs, the strap can be both filed and bent over to close the spark gap.
On multi strap plugs, I’m assuming the same could be done, but care would have to be taken to achieving both specified height AND distance from the centre pin. A non trivial task.
Yeah. As I mentioned, I'm already sold on doing it for cars that get driven hard.
The other person I’m remembering is Robmypro who is not a track guy like Trakcar. I think his car only made one outing to the track when his plugs were responsible for rough running before factory change schedule.
Hello, completed my plug change. I am not the original owner and the service records I have suggest it has been 3 yrs since plug change. They may have been changed under CPO prior to my purchase last October. No issues noted with vehicle performance or codes.
Hello, completed my plug change. I am not the original owner and the service records I have suggest it has been 3 yrs since plug change. They may have been changed under CPO prior to my purchase last October. No issues noted with vehicle performance or codes.
Does the passenger front (cyl 6) look quite different to the other 5?
Looks very grey (lean) in the photo, but hard to tell from a photo.
Does the passenger front (cyl 6) look quite different to the other 5?
Looks very grey (lean) in the photo, but hard to tell from a photo.
I would say no. Each plug looks pretty darn the same. If you consider the 4 viewable "slot's" per plug; each plug has one slot that is just a bit darker than the other 3. Consistent across all 6 plugs.
08-30-2021, 11:10 AM
