eiioo4
Fig
.
9
.
Remove
ignition
coils
on
6-cylinder
engine
by
disconnecting
harness
connector
and
removing
mounting
bolts
(arrows)
.
NOTE-
"
The
compression
gauge
reading
shoutd
increase
with
each
compression
stroke
and
reach
near
its
maxi-
mum
reading
in
about
4-6
strokes
.
"All
cylinders
shoutdreach
maximum
compression
in
the
same
number
of
strokes
.
If
a
cylinder
needs
sig-
nificantly
more
strokes
to
reach
maximum
compres-
sion,
there
is
a
problem
.
7
.
Release
the
pressure
at
the
compression
gauge
valve,
then
remove
the
gauge
from
the
spark
plughole
.
Re-
peat
the
test
for
each
of
the
other
cylinders
and
com-
pare
the
results
with
the
values
given
below
.
ENGINE-GENERAL
1
:00-
7
Compression
Pressure
"
Minimum
..........
.
.
..
..
10-11
bar
(142-156
psi)
"
Maximum
difference
between
cylinders
..
.....
.........
0
.5
bar
(7
psi)
Reinstall
the
spark
plugs
and
spark
plug
wires
or
ignition
cofs
.
The
remainder
of
installation
is
the
reverse
of
removal
.
Be
sure
to
reihstall
al¡
wires
disconnected
during
the
test,
especial-
¡y
ground
wires
at
the
coils
and
cylinder
head
cover
(where
ap-
plicable)
.
Tightening
Torque
"
Spark
plug
to
cylinder
head
.......
25
Nm
(18
ft-Ib)
Low
compression
indicates
a
poorly
sealed
combustion
6
.
With
the
parking
brake
set,
the
transmission
in
Park
or
chamber
.
Relatively
even
pressures
that
are
below
specification
Neutral,
and
the
accelerator
pedal
pressed
to
the
floor,
normally
indicate
worn
piston
rings
and/or
cylinder
walls
.
Erratic
crank
the
engine
with
the
starter
.
Record
the
highest
values
tend
to
indicate
valve
leakage
.
Dramatic
differences
be
value
indicated
by
the
gauge
.
tween
cylinders
are
often
the
sign
of
a
failed
head
gasket,
bumed
valve,
or
broken
piston
ring
.
Engine
Mechanical
Troubleshooting
Table
Table
c
lists
the
symptoms
of
common
engine
mechanical
problems,
their
probable
causes
and
the
suggested
corrective
actions
.
The
bold
type
indicates
the
repair
groups
where
appli-
cable
test
and
repair
procedures
can
befound
.
MECHANICAL
TROUBLESHOOTING
