Yes, exactly the same, round. As for the coils, I didn't change those.

 

So a five sided 14 mm casing on the plug? Not the 12 point showing on some? A "normal" shape on the tip of the plug?

Here's what Rockauto shows for Bosch 8124 for 2017 911.2 3.0T - single ground and 12 point shape with differently shaped tip ... is this like the ones you removed and put back in?


12 point body (casing) different tip single ground

 

As I recall, the plugs that went in were exactly the same as what came out and the old plugs match what you posted, so yes.

 

I'm impressed - you had a 12 point socket on hand?!

Here's a thread wherein a fellow (991.1 NA) was having a miss on #6, due, apparently, to torn rubber boot - perhaps this application is pretty sensitive to grounding out to the head?

https://rennlist.com/forums/991/1143932-fault-codes-after-changing-spark-plugs-1.html

 

I thought I did all my homework in researching parts and tools needed for the work I did. I did not have that socket in inventory but purchased it for the job. I opted for the one with the crown grip inside to hold the plug. I have changed dozens (hundreds?) of plugs on various vehicles...

 

And, you checked the gap at 0.7mm (0.0275")? (this was shown in a previous thread ... it is not from a Porsche manual or book)

Here's thread with dealer swapping plugs at 10K on a 911.2 C2 with same result - apparently plugs? (still odd, since what are the chances of TWO bad plugs?) https://rennlist.com/forums/991/1266...-question.html

 

Just don't confuse it with the Loctite.

 

hcamp,

Can you update us?

 

All fixed but still some mystery! To summarize what happened: I did PM on car the last week of Jan. including plugs and air filter. Drove 3 times after that for about 35 miles total and after a spirited drive in Sport Plus I got "engine control fault" and a engine check light. As I continued carefully driving towards home I got one that said "PDK overheating, reduce engine load". So I stopped, towed it home and commenced to evaluate using iCarsoft. The tool showed "roughness" (not "misfire") on #3 and #5. I switched the plugs and coils between #2 and #3 and no change, still showing #3 and #5 roughness. I removed the bumper cover and double checked all hoses and connections I had touched. Nothing found so I was then thinking ECU or sensor and decided to take it to a indie German car shop to be professionally evaluated. They found misfires on #5 and #3 and replaced the plugs and coils. I picked up the car today, drove it a few miles until it was warmed up and went to a area where I could put it in Sport Plus again and drive it hard and all good so far. I will put more miles on it soon to verify no more issues. I now have 65 miles on the plugs I replaced and the original coil packs in the other cylinders.



Two items of note: 1) The shop told me that when they contacted their parts suppliers, one did not have any of the needed coils in stock and both companies told them that they had been selling a lot of these particular OEM Eldor coils. May be a problem of frequency of coils failing? This surprised them. 2) Why did the roughness issue not follow the switch to #2? I marked the coil pack when I did the switch and it clearly still shows a "2" on it! Maybe it was just the plugs? The plugs they took out look great, no cracks or fouling.



I asked about bench testing the coils for resistance and they said they don't do that because the coils typically fail under load. This could explain why the spirited driving brought the issue out. They also stated that, on the Turbo S's they always replace the coil packs at the same time as the plugs but have never had a need to do that with the Carreras.



To clarify a previous post I made regarding these plugs, I wasn't thinking "ground" electrode/strap but these plugs are indeed single ground.



I guess I learned something, go ahead and replace the coil packs in the first place. I hope this is good info for all of you who were kind enough to give me your time and input. To those who initially said coil packs, you win the Kewpie Doll.

 

@hcamp19 I'm sorry but I got lost on that last post. Can you summarize what the problem was and what the solution was? Was the problem bad coils? And did you replace them all or just certain ones? Sorry if I missing something here but there have been so many different updates I'm just a little confused.

 

I am now confused, as well.

In summary, the dealer replaced all the coils and plugs (you already did this) and now everything works, or did they replace coils and plugs only on 3 and 5? And, the first test showed misfire only on 5?

So, we don't really know what was broken and needed to be fixed, and what was unnecessarily replaced?

Were the plugs bad? Coils? Both?

 

The indie shop replaced #3 and #5 only. They changed both the coils and the plugs so , no, we don't know which was the culprit but at $120.00 per hour, it's cheaper than troubleshooting each item separately. The big mystery is why the misfire didn't follow my switching #2 and #3 before taking it to them. I am recommending anyone with a similar issue replace the coils on the suspect cylinders (even at low mileage) as some here suggested. What threw me off initially was why the problem waited 35 miles after my work to show up but my guess is the load on the coils. Since I also changed the oil and did a brake flush, I still saved about $1600.00 on labor and parts over what the dealer would have charged so I would do all this again myself. Probably would go ahead and change the coils too given the apparent failure rate cited by the shop.

 

Good news that your car is repaired!

Thankfully it was only a coil issue!

 

BTW, anyone looking to do their own plugs that doesn't already have a socket should consider this one:


I used a standard thin walled socket but, given the angle of the plug in the tube, this one would likely make it easier, especially if you are not experienced at spark plug changes. And make sure you torques the new plugs to 22 ft lbs

 

I may be asking stupid questions as a Newbie, but wouldn’t the mech replace the coil on the one cylinder that is suspect (since it is 99.9999% won’t be the plug, and then crank the car up? If it runs right stop there? Same amount of time as walking around the car?