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Spark Plug and Coil Pack Replacement
 
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Pelican Technical Article:

Spark Plug and Coil Pack Replacement

Jared Fenton

Time:

2 hours2 hrs

Tab:

$30 to $300

Talent:

****

Tools:

Phillips head screwdriver, 10mm socket and driver

Applicable Models:

Audi A6 (1997-01)
Audi A6 Avant (1997)
Audi A6 Quattro (1997-04)
Audi A6 Quattro Avant (1997-01)

Parts Required:

Spark Plugs, Coil Packs

Hot Tip:

Swap the coil packs between positions to determine a faulty one.

Performance Gain:

Better running engine

Complementary Modification:

Perform compression check

One basic tune-up procedure for just about any car on the road is the replacement of your spark plugs and coil packs (if needed). I recommend inspecting your spark plugs every 60,000 miles, or about once a year. In reality, you can probably go longer than that, however, you never really quite know how long the plugs are going to last, or you may forget to replace them if you don't setup a yearly schedule. In practice though, the plugs in the A6 last a very long time. The coil packs are usually more of a problem. If you notice a slight roughness when the car accelerates sometimes along with a check engine light, you may want to investigate further.

On the A6 2.7T, there are six coil packs that sit on top of each spark plug, three on either side of the engine in a right and left bank. The coil packs can fail with no warning and cause the check engine light to illuminate. If it does, there is an easy way to determine which coil pack has a fault. By using a code reader or a diagnostic computer package, you can view if any diagnostic trouble codes that are stored in the car's memory. Additionally, most auto parts stores will typically be able to run your car's codes for free.

It's a good idea to let the engine cool for a bit before removing the plugs. If you try to remove or install spark plugs in a hot engine, you may encounter problems with the spark plugs gumming up or damaging the relatively delicate threads in the aluminum cylinder head. Make sure that the car is cold, or at the bare minimum, only slightly warm to the touch.

You'll need to remove the cylinder head covers, the air filter and cover and move the coolant expansion tank to access the coil packs/spark plugs. See our articles on Air Filter Replacement, and Coolant Expansion Tank Replacement for more information.

Each coil pack is held in place by two 10mm bolts. Once removed, you can carefully use a screwdriver to unlock the electrical connector from the coil pack. Once free, pull the coil pack out. All of the coils are the same, so it doesn't matter which cylinder it came off of - unless you are specifically trying to troubleshoot a bad coil fault code that was displayed by the main computer. You can even use the main computer to definitively isolate a bad coil pack by swapping it with another coil pack. If the fault code now presents itself on the cylinder you moved the suspected coil pack to, you know it is bad.

To remove the spark plugs, you'll need to use a thin wall 5/8" spark plug socket. It is wise to check the condition of each plug before installing the new ones. The color of the plug is a good indicator of how the engine is running. Ideally, you want to see a slightly tan looking plug. This typically means that the engine is running well.

Install your new plugs using a torque wrench to measure the amount of torque applied to the plug. This is very important, as it is easy to over or under-tighten spark plugs. Make sure that the plug is firmly seated in your spark plug socket as it is very easy to insert the plug into the head and have it cross-thread. This means that the threads of the spark plug don't mesh properly with the ones in the head, instead choosing to "cut their own path." This damages the threads on the heads, and in extreme cases, may destroy the threads in the cylinder head entirely. Trust me - you do not want this to happen. Proceed carefully and cautiously here. Install each spark plug into the cylinder heads without using any anti-seize compound. Torque the spark plugs to 30 Nm (22 ft-lbs).

With the new plugs installed and tightened to the correct torque, you can replace the coils and reattach the coil connectors. Now reattach the cylinder head covers, turbo inlet pipes, the air filter and cover and re-install the coolant expansion tank in place.

Once you are finished, start the car and enjoy your smooth running engine. Note that for purposes of clarity, left and right sides are looking towards the engine from the front of the car. Additionally, this article is specific to the 2.7T V6 engine, but the 2.8L V6 is similar enough to use this article as reference.

Left Side of Engine: Use a Phillips head screw driver to loosen the two plastic locking tabs (green arrows) on the cylinder head cover.
Figure 1

Left Side of Engine: Use a Phillips head screw driver to loosen the two plastic locking tabs (green arrows) on the cylinder head cover. You'll need to press them down slightly and then turn counter-clockwise.

Left Side of Engine: Note the turbo inlet pipe at the front of the cylinder head.
Figure 2

Left Side of Engine: Note the turbo inlet pipe at the front of the cylinder head. You'll need to remove a 10mm bolt (green arrow) under the hose (purple arrow). Pull the hose back to access the bolt.

Left Side of Engine: Once the bolt is removed, you can move the turbo inlet pipe slightly forward to access the forward-most coil pack mounting bolt (purple arrow).
Figure 3

Left Side of Engine: Once the bolt is removed, you can move the turbo inlet pipe slightly forward to access the forward-most coil pack mounting bolt (purple arrow).

Right Side of Engine: You'll need to physically move the coolant expansion tank (green arrow) up and out of the way to access the coil pack and spark plugs on the right side of the engine.
Figure 4

Right Side of Engine: You'll need to physically move the coolant expansion tank (green arrow) up and out of the way to access the coil pack and spark plugs on the right side of the engine. See our article on Coolant Expansion Tank Replacement for more information.

Right Side of Engine: Use a Phillips head screwdriver to loosen and remove the two plastic locking tabs (green arrows).
Figure 5

Right Side of Engine: Use a Phillips head screwdriver to loosen and remove the two plastic locking tabs (green arrows). Also loosen and remove the oil filler cap (purple arrow). Now remove the cylinder head cover from the right bank of the engine.

Right Side of Engine: Like before on the left side of the engine, pull the hose (green arrow) back to access the 10mm bolt (purple arrow) securing the turbo inlet pipe to the cylinder head.
Figure 6

Right Side of Engine: Like before on the left side of the engine, pull the hose (green arrow) back to access the 10mm bolt (purple arrow) securing the turbo inlet pipe to the cylinder head.

Both Sides of Engine: At this point, the details between left and right sides are pretty similar.
Figure 7

Both Sides of Engine: At this point, the details between left and right sides are pretty similar. Note the 10mm bolts (green arrows) securing the coil packs to the cylinder head. Note that on our project car, one of these bolts is missing. It also appears that a previous mechanic numbered some of the coil packs trying to determine a bad one.

Both Sides of Engine: Use a screwdriver to carefully pry open the locking tab holding the electrical connector to the coil pack.
Figure 8

Both Sides of Engine: Use a screwdriver to carefully pry open the locking tab holding the electrical connector to the coil pack. It should come off pretty easily.

Both Sides of Engine: Now remove the two 10mm mounting bolts and pull the coil pack out of the cylinder head.
Figure 9

Both Sides of Engine: Now remove the two 10mm mounting bolts and pull the coil pack out of the cylinder head.

Both Sides of Engine: Use a thin wall 5/8 spark plug socket with an extension to remove the spark plug from the cylinder head.
Figure 10

Both Sides of Engine: Use a thin wall 5/8" spark plug socket with an extension to remove the spark plug from the cylinder head.

Both Sides of Engine: And here's the final result with the spark plug removed.
Figure 11

Both Sides of Engine: And here's the final result with the spark plug removed. Installation of the new spark plugs/coil packs is the reverse order of removal. Be sure to torque the new plugs to the specified value of 30 Nm (22 ft-lbs).

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Page last updated: Sun 5/28/2017 03:20:58 AM