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Pelican Technical Article:

Spark Plug Replacement

Steve Vernon

Time:

1 hour1 hr

Tab:

$4 to $40

Talent:

**

Tools:

13/16-inch spark plug socket, extension

Applicable Models:

Porsche 944 Turbo (1986-89)

Parts Required:

New spark plugs

Hot Tip:

Work with the engine cold

Performance Gain:

More power

Complementary Modification:

Change cabin air filter

Changing spark plugs is one of those time-honored maintenance tasks that any self-respecting car enthusiast should do yourself. It's usually easy to do and it gives you a chance to feel like a real gear head without having to get all that dirty or spend hours writhing around on the floor of your garage.

Granted, some of today's cars are packaged so tightly that it can be very difficult to reach the plugs, and some modern cars have extremely long recommended service intervals for spark plugs, further decreasing the incentive to DIY.

In the case of the 944 Turbo engine, however, it's quite easy to change the spark plugs. That's a good thing, because turbocharged engines tend to be harder on spark plugs. In addition, if your turbocharged engine isn't running quite right, it is quick and relatively inexpensive to eliminate the spark plugs as a potential source of the problem through a plug change.

Porsche recommends that you change the plugs every 30,000 miles or two years, whichever comes first.

It is a very good idea to change the plugs when the engine is cold. If the engine is hot or warm, the threads in the head are much more susceptible to damage from stripping or cross threading.

Begin by disconnecting the ground on the battery. Please see our article on battery maintenance and replacement.

The spark plugs on the 944 are located on the top of the engine and are accessed between the intake runners (yellow arrows).
Figure 1

The spark plugs on the 944 are located on the top of the engine and are accessed between the intake runners (yellow arrows). The plug for the number one cylinder is located in front of the intake runner between the turbo pipe (green arrow). The wires going to the plugs are attached to the distributor mounted on the front of the head (red arrow).

This photo shows a close-up of access to the plugs.
Figure 2

This photo shows a close-up of access to the plugs. You can see there is easy access to the numbers 2, 3 and 4 plugs, while number 1 is partially hidden (yellow arrow).It is much easier to change the number 1 plug if you remove the turbo pipe. While it is possible to change the plug out without removing the pipe, if you are doing this for the first time, do yourself a favor and remove the pipe.

Remove the three fasteners securing the air box lid to the base (red arrows).
Figure 3

Remove the three fasteners securing the air box lid to the base (red arrows).

Disconnect the line running to the turbo pipe with a 17mm wrench.
Figure 4

Disconnect the line running to the turbo pipe with a 17mm wrench. Note that there are two washers (red arrows) that need to be replaced if you remove the line.

Disconnect the clamp over the pipe by reaching down and unclipping it.
Figure 5

Disconnect the clamp over the pipe by reaching down and unclipping it. Then remove the lid. Next, use a flathead screwdriver and loosen the hose clamps on both ends of the pipe (red arrows).

Remove the pipe from the engine (red arrow).
Figure 6

Remove the pipe from the engine (red arrow).

With the pipe removed you can see the spark plug wire, boot and how much more room you have to work (red arrow).
Figure 7

With the pipe removed you can see the spark plug wire, boot and how much more room you have to work (red arrow).

Gently wiggle and pull the wire boot from the top of the plug.
Figure 8

Gently wiggle and pull the wire boot from the top of the plug. There is a special tool for removing the wires that fits in the rings on the bottom of the boot (red arrow). If you take your time and care, you can remove the wire without using it. Do not just grab the connector by the wire and pull, as you run the risk of tearing or separating the cover (yellow arrow).

Using your 13/16-inch spark plug socket and an extension to clear the intake runner, remove the plug from the engine (red arrow).
Figure 9

Using your 13/16-inch spark plug socket and an extension to clear the intake runner, remove the plug from the engine (red arrow). The engine should be cool to the touch especially when installing the new plugs. You want to make sure the plug is properly seated to avoid cross threading the plug in the head.

Check the condition of the plugs when you remove them.
Figure 10

Check the condition of the plugs when you remove them. The condition of the plug can tell you a lot of information on the health of the engine. The plugs on our project car had oily deposits on them, which is indicative of leaking valve seals or piston rings. Installation is the reverse of removal. I like to place a small amount of di-electric grease between the top pf the plug and the connection and make sure that the connections are properly seated when reinstalling the wires. To avoid cross threading, start by screwing in the spark plug by hand, or hand and socket wrench/extension. Then tighten with your spark plug socket, extension and socket wrench.






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Comments and Suggestions:
Alstheone Comments: What is the correct gap for the plug? What torque should the plug be tightened to?
August 14, 2016
  Followup from the Pelican Staff: You didn't mention what vehicle you have. I don't have the torque info for vehicles.


I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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