Overview:
If you have about 3 to 4 hours of time, basic mechanical skills,
and a few tools, you can change, re-gap, or inspect the spark
plugs yourself. You can use the money you save by not paying a
dealer to buy a good torque wrench and socket set. These are my
modifications to Brian LaFuente's (GT-Pro) advice. The front
plugs are easy and obvious. The back plugs can be accessed by
tilting up the plenum; the throttle body and all hoses are left
attached. Start at the back of the plenum and work forward. You
will need 10, 12, and 13 mm sockets, 5/8" spark plug socket
(with rubber insert to grasp plug), a flexible socket extension
(like a little universal joint), 3" and 6" socket extensions,
screw drivers, some wire, long needle nose pliers or forceps, a
torque wrench, and a little patience.

Removal:
1. Disconnect battery negative terminal (10 mm).
2. Disconnect the Y-pipe from the throttle body. This may
require loosening or removing the two intercooler pipes attached
to it, depending on your setup, and the air by-pass hose.
3. Remove the rear IC pipe completely for more working space and
stuff clean rags into the top of the turbo and the open IC pipe.
4. Remove the bolt (12 mm) holding the oil supply line near the
rear turbo for more working space.
5. Remove the accelerator cable bracket (two 10 mm bolts) and
set aside. Note the tension of the cable and/or the location of
the bolts in the bracket for the installation later.
6. Remove the two (10 mm) bolts that hold the 3-plug bracket on
the passenger side of the plenum. Remove the two bolts that attach the injector wiring harness to
the plenum.
7. Remove the passenger-side bolt (13 mm) from the EGR pipe (it
comes up from the rear cat near the oxygen sensor). Loosen (but
do not remove) the driver-side EGR pipe bolt, and slide the
metal gasket downward. Securely attach a wire to the gasket
(forceps can help with this), then remove the remaining EGR pipe
bolt. Set the gasket aside; it can be reused.
8. Carefully remove the two bolts (12 mm) attaching the rear of
the plenum to the stays (brackets).
9. Remove the three (12 mm) bolts from the plenum front, the two
long (12 mm) bolts from the plenum top, and the two (12 mm) nuts
from the plenum front sides. The plenum may pop a little with
the release of pressure.
10. Lift the plenum straight up to clear the front studs then
tilt toward the passenger side. Prop it up with something. A
foot-long 2x4 works perfect. The fuel pressure regulator hose
will probably slide off the throttle body, but the rest of the
hoses (including the clutch vacuum assist hose on the right side
of plenum) should have enough length to move the plenum around
without a problem.
11. Cover the intake manifold with a clean rag. You definitely
do NOT want anything falling in there. Now is a good time to
replace the gasket if it needs it.
12. Remove the wires from the plugs. Note the routing through
the brackets. They are of different lengths and not easily mixed up.
13. Clean and vacuum the plug areas to remove dirt and oil. You
do not want anything falling into the cylinders when the plugs
are removed.
14. The front plugs are easy to remove. The back ones may
require moving the plenum around some. I like to note which
cylinder each plug comes from for the next step.
15. Do what you need to with the plugs. Now is an excellent time
to inspect the plugs for color, oil, damage, burns, and
detonation specks (you may need a magnifying glass). This can
tell you how each cylinder is performing. If changing the gap,
be careful to not damage the platinum tips. Stock gap is 1.0-1.1
mm (0.039-0.043"). The proper spark plugs are platinum NGK
PFR6J-11 (or Denso PK20PR-P11 or equivalent) for the DOHC
engine, and NGK BPR5ES-11 (or Denso W16EPR11 or equivalent) for
the SOHC.
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