joeycannoli

This DIY article will assist you in changing your spark plugs in the 996 GT3. This article can also be used for all other 996 naturally aspirated motors. It is similar for the turbo, but additional steps need to be taken to remove the inter-cooler lines out of the way. I went with the OEM spark plugs from Porsche. They are made by Beru and can be had for $78 at Suncoast Parts.

Porsche Recommended Service Interval: Change Spark Plugs every 30k miles

Part Number: 999-170-195-90

Tools Required:

3/8 Ratchet (prefered flex-head)
6" Extension
5/8" Spark Plug Socket
5mm Allen Socket
10mm Socket

I performed this DIY on a lift. I am not sure how difficult it would be on jack stands, but if you have access to a lift i highly recommend it. I have heard people state the rear wheels should be removed if doing it on jack stands for more room, but i am not sure of this. Either way it will be more difficult on the ground as it will be a tighter work space.

I recommend letting the car cool down a little bit if you drove to the lift. They exhaust and heads will still be a little hot while working. Once the car has cooled we can start. There are 3 plugs on each side. I will be showing this DIY doing just one side, but the other is identical. Once under the car you will notice the coils are hidden by the shield shown below.



The shield is held on by the two 10mm bolts shown above. Grab your 10mm socket and remove them.



With the shield removed it will give us access to the 3 spark plug coils. Each coil is held on by two (6 total per side) 5mm hex bolts pictured below. Remove these next.



Here is a close up of how the coil is secured by the hex bolts.



Using a 5mm hex socket these bolts are easily removed.



With the bolts removed we can now work on disconnecting the coils from the harness. You will see the coil connector is covered by a rubber boot. Simply pull the rubber boot up to reveal the cover as shown below.



Here is a shot of the rubber boot pulled up to reveal the connector



This will expose the connector. Below is a close up of what the connector looks like



To remove the harness connector from the coil, press down on the rear of the connector as indicated below. This will release the connector and allow you to pull it free from the coil



Here is a shot of the connector free from the coil



Once you have removed all of the connectors from the coils you can easily pull them out. Here is a shot of them outside the car



Here is what we now have under the car with the coils removed



Next step is to remove the spark plugs. Grab your ratchet, 6" extension and spark plug socket



This step is pretty self explanatory. Insert your socket into the cylinder head to remove the spark plugs.

NOTE: The rear-most spark plugs are a little difficult to get to as there is less room to work. I had to slide the spark plug socket in first, followed by the extension and then finally the ratchet. I connected them all while they were in the cylinder and then loosened the plug. You might have to take the setup apart in pieces during removal too. I used a magnetic pick-up tool to finally pull the spark plug out once loose.



Here is a comparison of my old plugs vs the new plug. I am pretty sure they are the original plugs, which had 30k miles on them.



To install the new spark plugs and finish up this DIY you simply follow the instructions from here in reverse. Torque specifications for the spark plugs are 22 ft/lbs. However, i never use a torque wrench to tighten my plugs down as i am always worried about snapping a plug in the head. Snug and 1/4 turn will do just fine.

cgfen

Welcome back!

Nickshu

I just did this about 2 months ago. If you put in new coilpacks they have an updated design that includes and E-Torx bolt instead of the original hex. The new coilpacks do not have the bolt holes recessed down the sides, they are nearly flush with the top of the coilpack, which is actually easier to get access to when removing/installing.

Marv

Thank You!

I always appreciate the "Press Here" diagrams when removing connectors!!!

A job I need to do very soon, myself.

M

sp0da

Awesome write-up, thanks! I've changed the plugs a few times in 7 years of ownership, and the one tool that makes this job a lot easier is having a set of magnetic spark plug socket+extensions, like these:

Ted Striker

Hi, thank you for your detailed instructions. When changing the plugs, I would like to check the compression. Does anyone know, what to disconnect, to eliminate the ignition while turning the starter to check the compression? A fuse? A cabel? Is there a instruction for that? I haven't found one. Best Regards, Freddy

Stephen Tinker

Fuse C2 isolates the electronics / fuel injection system and fuse C4 isolated the fuel pump. To accurately complete the compression test, all plugs should be removed, the engine should be hot and the throttle body fully open when cranking.

spiller

Thanks for the write up. Can anyone tell me what to look for with a bad coil? Is it just cracking around the end of the stem?

Stephen Tinker

Cracks usually happen on the coilpack body - this lets moisture in behind the insulation protecting the copper coils. The moisture (or more specifically the salts / dirt in the moisture) short the voltage through to the outside of the coilpack and then to the cars ground.
Basically a coilpack is a transformer with primary and secondary windings converting 12v to 20,000v so it can jump the spark plug air gap. These embedded copper coils are encapsulated in resin and are maintenance and wear free until heat, vibration, or mechanical damage to the coil pack compromises the insulation properties of the resin.The voltage drop @ the plug is what causes a misfire.

Ted Striker

Hi Stephen, thanks for your reply. Yes I have also already found the fuses for those to aggregates. I have now heard, that one should leave the fuel injection on, so fuel will be sprayed into the chambers, which will increase the compression level. Should one do so, or better not. I would only remove the fuse for the ignition.

You are writing, that all plugs should be removed while testing. Do you just mean the ignition coils or realy the sparkplugs? I have never heard of it, to remove all, while testing. What would be the difference and what would be the advantage?

Thanking you in advance.
Freddy

Stephen Tinker

Freddy, the reason you remove the plugs is that the starter motor spins far quicker with them removed than if the plugs are still in situ and the starter motor is pushing against compression - 350 rpm vs 1500rpm.
Compression tests are not particularly difficult but considering you should remove the coilpacks, remove the plugs and fit in your compression tester (all on a hot engine), while a second person opens the throttle body as you crank the motor is a pain in the ***....
Re removing the fuel injection fuse, spraying raw fuel into the bores is questionable too - apart from washing any oil from the bores, it "could" give a false compression reading, which is defeating the object.

spiller

Ted Striker

Hi Stephen, thanks a lot, that makes sense. I will keep you updated. :-)

Stephen Tinker

The body is the rectangular section that connects to the harness, that's what contains the electrical coils.....

spiller