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PGM-FI System
Random Misfire
The scan tool indicates Diagnostic Trouble Cod. (OTC)
1
P0300
I",
1
P1300 1*'
and
some
of
"I
P~0"'3"'0"1;---t
"
h-r-o-u-
g'h--;P"'0"3"0'"'41
P0300", P1300" and
some
of P0301
-
P0304: Random
misfire.
Description
Misfire
detection
is
accomplished by
monitoring the crankshaft speed with
the crankshaft
speed fluctuation
(CKF) sensor
which
is
attached to the
crankshaft.
If misfiring
strong enough
to damage the
catalyst
is detected, the MIL will blink during the time of its
occurrence,
and OTC
P0300", P1300"
and some
of OTCs P0301 through P0304 will be
stored.
Then, after misfire has
ceased
,
the MIL will
come
on.
If misfiring
that
increases
emissions
is detected during two consecutive driving
cycles,
the MIL will
come
on,
and
OTC
P0300", P1300"
and some of
OTCs P0301 through P0304 will be
stored.
NOTE: If some of the OTCs listed
below are
stored at the
same
time as a misfire
oTC,
troubleshoot those
orcs
first,
then
troubleshoot the misfire DTe.
P0106,
P1128, P1129:
MAP
sensor
P0171, P0172: Fuel metering
P0505: Idle Control System
P1336, P1337: CKF
sensor
P1361, P1362: TOC
sensor
P1381,
P1382:
CYP
sensor
P1508: lAC
valve
'1:
'97
model
'2:
'98
- 00 models
Possible Cause
•
Fuel pump insufficient fuel
pressure,
amount offlow
• Fuel
line clogging,
blockage,
leakage
•
Fuel filter
clogging
•
Fuel pressure regulator stuck
open
•
Distributor malfunction
•
Ignition
coil
wire
open,
leakage
•
Ignition
control
module
malfunction
• Valves
carbon
deposit
•
Compression low
•
Fuel does not meet Owner's Manual
spec.,
lack
of
fuel
Troubleshooting
By test-driving, determine the
conditions
during which
misfire occurs.
Depending
on these conditions,
test in the order
described
in
the table below.
:
\-
Possible cause
Crankshaft
Fuel
Distributor and
Valve
-
------
-
------
-
---
-
~,
speed fluctuation
Ignition wires
ICM
Clearance
Page
"
'"
sensor
pressure
~
------------------_.
-------------
-
-.
------------_._-----
------
.
_-----
.
-
-----------.-----
Condition
section
6
11-178
section
23
section 23
section
6
Only low rpm and load
@
<D
@
Only accelerating
@
<D
@
Only high
rpm
and load
®
<D
@
@
@
Not
specification
®
<D
@
@
@
NOTE: If misfire
doesn't recur,
some possible
causes
are fuel that doesn't meet
owner's
manual spec,
lack of
fuel,
carbon
deposits
on
spark
plug.
etc.
11-126
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Troubleshooting
