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Audi A8 Replacing A8 Sparkplugs

If Bosch Platinum +4 (Model number 4457) sparkplugs are used: do not gap them. Also no anti-seize should be used, no matter what type of sparkplug. Bosch Platinum +4 are great but relatively expensive from an Audi dealership (around US$ 10-12). Buy them at local auto parts stores for about US$ 6.

Tools required for removal and installation of sparkplugs

The removal and installation of sparkplugs requires only a couple of tools:
  • 5 mm Allen wrench (to remove engine covers)
  • Phillips head screw driver (to loosen air intake hose clamps)
  • 10 mm wrench (to remove coil packs)
  • Torque wrench (22 foot/pounds, to remove and install sparkplugs)
  • Wrench extension (10 inches, because of deep sparkplug shaft)
  • Spark plug socket (5/8 inches, standard socket does not fit a sparkplug)
  • Adhesive tape (1-2 inches, so sparkplug socket is not left inside sparkplug shaft)
  • Flathead screw driver and socket wrench with 10 mm socket are optional.

    Step 1: Move air intake hose up

    With a Phillips head screw driver, loosen up the hose clamp (A) around the air intake hose going to the air filter housing so the hose can be detached. Also, loosen the other hose clamp (B) just enough for the entire hose assembly to move up to allow removal of the left engine cover.

    The picture above shows the air intake hose moved up
    and the engine covers already removed.

    Step 2: Remove Engine Covers

    With a 5 mm Allen wrench, remove the left, then the right and finally the middle engine cover. Both side covers have 2 bolts each next to the Audi rings. The middle cover has 4 bolts on each corner. This is a nice opportunity to clean the covers with water and soap.

    It's best to replace the spark plugs, one at a time, from front to back (Cylinders 1,2,3,4 then cylinder 5,6,7,8) making it easier to keep the wiring to the coils nice and neat. The cylinders are numbered on top of the engine block, visible after removal of the engine covers.

    Step 3: Remove Coil Pack
    With a 10mm wrench, remove the two bolts keeping the coil pack in place. Then lift the coil pack out of its shaft and lay it on the side, still connected to its wires.

    As you can see in the picture above, the bottom part of the coil pack that connects directly to the spark plug is somewhat flexible which helps getting it in and out. You may have to partly remove a neighboring coil pack to be able to remove one completely out of the shaft it's in. With this car, this was only necessary to remove the coil pack of cylinder 7: bolts of coil pack of cylinder 8 were removed first.

    Attach the wrench extension (10 inches) and 5/8 inch spark plug socket to the torque wrench. If you want to be absolutely sure that the socket fits the spark plugs: get the spark plugs first and fit one of them into the converter.

    Step 4: Remove and install sparkplug

    Wrap a piece of adhesive tape around the wrench extension and the spark plug socket. This way there's no chance the spark plug socket will be left behind in one of the spark plug shafts after putting a new plug in.

    Place the tool in the plug shaft and remove the spark plug without applying force sideways. Place one hand right on top of the pivot point of the wrench to keep the tool steady.

    After the plug is removed from the engine, take it out of the socket.

    Take the new sparkplug out of its box but do not remove the paper cover wrapped around it. This will keep it grease free until after the plug is put into the sparkplug socket. Bosch Platinum +4 (Model number 4457) sparkplugs don't need to be gapped. Also, don't use anti-seize for any type plugs for the 1994-2003 A8/S8.

    Set the torque wrench to 22 foot/pound of torque. Place the new sparkplug into the socket. Take the paper cover off the sparkplug and install it. When the plug is hand-tight, slowly tighten the plug until the wrench clicks. Then loosen the plug again by two turns and then finally tighten it again.

    Place the coil pack back into the shaft. Check whether the wiring can run as before to the coil pack. Tighten both the coil pack's 10 mm bolts. Repeat step 3 and 4 for the remaining cylinders.

    Step 5: Re-install engine covers
    With a 5 mm wrench, put on the middle engine cover first, then the left and right one.

    Step 6: Re-install air intake hose

    Move the air intake hose down so the end of it can be reconnected. When re-attaching the hose, make sure it wraps completely around the air filter housing and to line up the index marks on the hose and the air filter housing (see picture above). Tighten hose clamps with a screwdriver

    Job done! Go drive and enjoy a more responsive car!

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