FUEL INJECTION SYSTEM TROUBLESHOOTING
SERVICE MANUAL NUMBER 24
Page 5F-12
90-861327--1 OCTOBER 1999
Detonation / Spark Knock Symptom (Continued)
Step
Action
Yes
No
PROCEED TO
11
1. Check fuel delivery system items that can
cause an engine to run lean.
Was a problem found?
Step 12
12
1. Check for ECT sensor being shifted in
value.
2. Check for proper output voltage of the TP
sensor at closed throttle and wide open
throttle. Also check throttle linkage for stick-
ing, binding or worn.
Was a problem found?
Step 13
13
1. Check for the following Engine Mechanical
problems:
•
Low compression.
•
Low oil level.
•
Excessive oil in the combustion chambers
due to valve seals leaking.
•
Worn or incorrect camshaft.
•
Proper valve timing/valve train problem.
•
Combustion chambers for excessive car-
bon build up.
Was a problem found?
OBD
Step 14
14
1. Remove excessive carbon buildup with a
top engine cleaner.
•
Refer to instructions on top engine
cleaner can.
2. Re-evaluate engine performance.
Is detonation still present?
Step 15
OBD
15
1. Review all diagnostic procedures within
this table.
2. If all procedures have been completed and
no malfunctions have been found, review/
inspect the following:
•
Visual/physical inspection.
•
Scan tool data.
•
All electrical connections within a sus-
pected circuit and/or system.
Was a problem found?
OBD
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Customer
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