Subaru 2006 Legacy, Manual

Page: 2021 / 4302

GD(H4DOTC)-99
Diagnostic Trouble Code (DTC) Detecting Criteria
GENERAL DESCRIPTION
When a misfire occurrs, the engin speed will decreased and the crankshaft position speed will change. Cal-
culate the interval difference value (diagnostic value) from crankshaft position speed by the following formu-
la, and judge whether a misfire is occurring or not comparing the calculated result with judgment value.
Counting the number of misfires, if the misfire ratio is higher during 1000 revs. or 200 revs., Judge corre-
sponding cylinders as NG.
As shown in the following figure, pick a cylinder as the standard and name it omg 0. And the former crank-
shaft position speed is named omg 1, the second former crankshaft position speed is named omg 2, the third
is named omg 3, etc.
Diagnostic value cal-
culation
(Calculate from angle
speed)
→
Misfire detection every sin-
gle ignition
(Compare diagnostic value
with judgment value)
→
NG judgment (Misfire occurrence judg-
ment required by the law) (Compare
number of misfire with judgment)
• 180° Interval Difference
Method
• 360° Interval Difference
Method
• 720° Interval Difference
Method • FTP1.5 times misfire NG judgment
• Catalyst damage misfire NG judgment
(A) Ignition order (B) Crankshaft position speed
EN-01774
#3 #2 #4 #1 #3 #2 #4 #1 #3 #2 (A)
(B) omg0 omg1 omg2 omg3 omg4 omg5 omg6 omg7
asieps_tobira.book 99 ページ ２００９年１０月２６日 月曜日 午前９時１６分