Navistar N9 Diagnostic Manual page 41

1 DIAGNOSTIC TROUBLESHOOTING PROCEDURES
Step 3 Record snapshot of engine running data and determine if engine has a misfire.
Perform Record Snapshot of Engine Running Data (page 2231) while
symptom is occurring.
Does engine speed vary by 50 rpm or more while symptom is occurring?
Step 4 Determine if engine has low power or slow acceleration.
Review engine running snapshot.
Does vehicle have low power or slow acceleration?
Step 5 Determine if engine is able to reach desired speed during PTO operation.
A. Start engine.
B. Operate PTO.
C. If vehicle is equipped with a manual PTO, increase engine rpm to
desired operating speed.
Does engine reach desired speed during PTO operation?
37
Decision
Yes: Go to 5.2 Misfire
(Stumble/Surge/Runs
Rough) (page 80).
No: Go to Step 4.
Decision
Yes: Go to 5.1 Low Power
(Slow Acceleration) (page
74).
No, if equipped with Power
Takeoff (PTO): Go to Step 5.
NOTE: No, if not equipped
with PTO: review operator
complaint.
Decision
Yes: Review operator
complaint.
No: Go to 5.3 Engine Unable
to Reach Desired Speed
During PTO Operation (page
84).