Mike in CA

The factory maintenance schedule specifies spark plug replacement for my 2014 GT3 every 12,000 miles, but no later than every two years regardless of mileage.

What is the rationale behind the 2 year interval? I had the plugs replaced just over two years ago so technically I'm now due for service, but my mileage in that time is a small fraction of 12K miles.

No comments, please, about how I should drive the car more.

bittrl1000

In my experience, plenty of people are on either side of this issue. Some will say that you should follow the Porsche instructions...that changing plugs more frequently helps avoid seized plugs. Others will say that changing plugs that frequently is at best a waste of money, and at worst increases the likelihood of screwing it up. I tend to be in the former camp, in that I like to follow Porsche's maintenance schedule. But I don't think you're being reckless if you change plugs less frequently, especially if you aren't even close on mileage.

GrantG

I know one of our resident experts, Trakcar, has said that he actually found it necessary to change more frequently than Porsche's recommendation (.1 RS with lots of track time). I think he settled on 6k miles and 1 yr in order to keep things running smoothly (plugs removed at the factory intervals looked bad and car idled roughly).

Also, Robymypro who tracks seldomly had misfires on his .1 GT3 from plugs going bad before the factory intervals as well.

If the car sees little or no track use and is running great, then maybe you could go a little longer. But for myself, I would err on the side of changing them at least as regularly as Porsche recommends (it's not very expensive nor time consuming).

Check from post# 204:
https://rennlist.com/forums/991-gt3-...k-miles-6.html

A/S

Every 1,200 track miles or every year or every 12k street miles (if the car is never tracked) whichever happens first. I'm on my 2nd set in less than 3,000 total miles, and I'm about to replace them again with an oil change in a few weeks.

I use the Cobb tuner from my 991 Turbo S to read the RS ECU, I have only experienced misfires in 3 situations: first time bad plug (replaced all of them), the other 2 times I ran out of fuel.

Mike in CA

Aside from the fact that I was dreading the 90 mile round trip to the dealer, wasting a full day, and spending $550 on a plug change, I was curious as to what kind of degradation occurred in the spark plug over the two year period if only low street miles were involved.

I've always been a stickler for the factory maintenance schedule so I suppose I should just bite the bullet and do it. I went back and found SmokinGTS's DIY on plug replacement, and the engine is due for it's annual oil change anyway, so I might as well get all the parts and make a fun afternoon of it.

Thanks for the feedback.

robmypro

Mike in CA

That's something I'd prefer to avoid, Rob.

Not to beat a dead horse at this point, but what you experienced is a symptom of plug degradation, not a cause. I just wonder what happens to the plug that renders it problematic simply due to the passage of time, in this case 2 years, regardless of how or how much the car is driven.

PS Just noticed I misspelled "replacement" in my thread title. duh....

0to60

I agree with you. If the spark plug sits on a stock shelf or inside a cylinder head is it really degraded ?

SmokinGTS

Hi Mike I just did my plugs again but more importantly I changed the ignition coils as well. My Gt3 and Boxster S use the same coil and I have had failures on both cars from these. Beru came out with an improved ignitor last digits were 07. I replaced all of these on both cars. These cost me a track day as well as a tour with the club. It totally makes sense to do these at the same time. You can buy the Porsche Bosch plugs now for $5 each and if you look online you will be able to buy the ignitors at half the normal price. The process is so easy on a GT3 unlike the Boxster.

Mike in CA

Hi Ed: My car has few miles (probably a lot less than yours) and I've experienced absolutely no symptoms of drivability or performance issues to date so I think I'll wait until next time to do the ignition coils. I appreciate the tip, though!

SmokinGTS

I would purchase a new ignition coil and have it ready to go as there is no warning when they decide to go south. This also just happened on my buddies GT3. My parts guy says he can't keep them in stock.

Mike in CA

Sounds like good advice.

robmypro

TRAKCAR

Mike,

Just do it as per manual at least. Cheap insurance and it wouldn't be so bad to do it each year when the annual is due.
While at it do the belt as well.

Assuming that 50% of the miles are on track:
What Grant said above ^^^
I can confirm that once a year or 12K miles isn't enough for plugs, so I am doing every 6 months and 6000 miles.
It could use more changes, if the car needs to go in for whatever reason I do it as soon as 3000 miles.
I do oil every 6 or so track days. PDK oil and all filers annually as well.

Also the belts need to be done every 12,000 miles. Mine was split after 2 year and 24,000 miles..
So my next oil change will be at about 32,000 miles the end of this year and I will do everything again, just to be safe.
That should take it to the end of its warranties track life on just oil changes and a couple more set of plugs by the end of 2019.

I have already done the uprights, wheel locks and bolts at about 12,000 track miles and these are going to have to make it till then as well.

When its retired to DD duties, I will just follow normal schedules.

Mike in CA

Peter,

Well, that's what I've decided after sleeping on this. I've also ordered a set of ignitors per Ed's (SmokinGTS) advice and will replace the old ones at the same time as I do the plugs and oil change. It felt wrong to contemplate putting the old parts back in there. Considering that all the labor will be mine, and my labor these days is cheap, it is a relatively inexpensive project.