One of the preceding threads where someone replaced a pristine water pump at 52K miles, got me thinking about spark plugs. I have an 05 C2S which I have owned from new. 28K miles on the clock. My local Porsche indy, who I think is really knowledgeable and sensible has not recommended doing them so far. His reasoning is that if one does go bad it will throw a CEL and we can just do it then. I think I have read threads where others have replaced at much higher miles with no evidence of wear or malfunction. The car runs flawlessly, (I'm knocking on wood). Would you mess with something that may not need to be messed with?
Jim

 

6 years or 60K miles works for me but even that may be overkill. Or you can change them when they get dirty

 

Check your owners manual or consult with a tech at the local dealer for the latest info but Porsche usually requires plugs be changed on miles, but also on time if the miles don't warrant a change.

The concern is the plugs can become corroded and seize in the head threads and possibly ruin the head when removed.

If you will look at the old plugs you'll notice the discoloration starts from the tip and runs up the threaded body. The combustion pressure and heat and heating and cooling cycles force/allow combustion byproducts to get between the plug and head threads where this can lead to corrosion.

Replacement of the plugs of course prevents this from progressing to the point possible damage can occur.

Even waiting for misfires is wrong. It takes a real bad plug to misfire. I've run the plugs in my Boxster for 90K miles and while there were never any misfires the plug tips were quite eroded both the center electrode and the 4 ground electrodes. Who knows what the "gap" was?

It was clear the plugs are due to be changed.

 

I don't think every 60k miles is excessive, but realistically, the plugs likely light off the mixture just fine.

 

Here's the way I look at it. Plugs are cheap and are easy to change so why not change them at 60k.

 

Have you changed it on yours yet?

 

Changed them this last spring. Ok I will admit a couple of them are a little harder to get to than the others.

 

2009 C2S.... Porsche denoted new plugs every 40K miles.... I just did my second change today at around 81K miles. No biggie, 4 hours of work.... about $120 for Porsche label Bosch plugs, or $44 for the exact same Bosch plug without the Porsche label. $44 bucks and 4 hours of work....... no big deal at all.

By the way, I removed the rear bumper and the side thingys and access to all bolts were easy! No need to go after that troika of evil at the cats... take the bolts off at the top. Even the plugs were straight on without a need for a universal joint on the plug ratchet. That 4 hours included bumper removal and tool storage.

To the original question: do we need such a frequent change? I suspect not and I believe it is done as a nod to the dealers. These 9A1 engines are turning out to be pretty darn bullet proof and I can't for the life of me understand why such frequent changes are needed.

Peace
Bruce in Philly

 

My 4 season car coils were cracked and rusted. Every three years for me. I try and keep to the book schedule. Looks good on resale too.
I'm with Bruce, source a fair priced part. Hunker down, get it done.

 

Iv slowed down accumulating the miles so it's going to be time based. But Porsche spec of 4years or 40k could be excessive. I've done the plugs after 4 years, took me a lot less time than Bruce since I did not take down the bumpers. Just raised one side remove wheels and muffler and then plugs. I will do my next plug service around 6 years. Plugs changed at 4 years looked very good.

 

My son and I did coils and plugs on our prior '07 007S, no need to remove rear tires, pop off rear bumper cover, and with the right tools and patience and small nimble fingers, several hours. Plugs and coils looked fine, but our car was never near salt. Now, a month ago, since our '07 GT3 had the motor out for welding the coolant pipes, I had Zuffenhaus do the plugs and coils, along with a lot of other "consumables", and got the plugs and coils back. The mechanic told me our '3's plugs and coils seemed to be good, but he has seen a lot worse.

While I think Porsche is more concerned about seizing plugs in the heads more so than simple diminished performance, I have removed severely eroded plugs from other engines that still seemed to perform well. So I think the issue is likely to be a gradual performance loss, not noticeable from the driver's seat. Changing out both plugs and coils is inexpensive and a reasonable thing to do once or several times over the life of the car.

Oh, had the water pump replaced at 29K miles in the '3. Preventive maintenance.

All the best....

 

Your coil packs are more likely to go 1st so when doing one, do the other.

 

Just had coils and plugs replaced at the dealer on my '08 C4S. Warranty covered coils and labor and I chipped in for plugs.

 

I did the coils and plugs this weekend on my 07 4S with 85k on it. The car started stumbling a little off the line, but otherwise seem to run normally. I don't think they have ever been changed.

You can see how the ground electrodes are worn down. They were definitely done.

Car runs great now.

 

The coil packs all looked like this