Suzuki Engine 2002 GRAND VITARA SQ625, Service Manual

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ENGINE GENERAL INFORMATION AND DIAGNOSIS (G16/J20 ENGINES) 6-85
TROUBLESHOOTING (DTC P0300/P0301/P0302/P0303/P0304)
Step Action Yes No
1 Was “Engine Diag. Flow Table” performed? Go to Step 2. Go to “Engine Diag. Flow
Table”.
2 Ignition System Inspection :
1) Check spark plug and ignition spark of cylinder
where misfire occurs, referring to “Spark Plug”
and “Ignition Spark Check” in Section 6F1 or
6F2.
Is it in good condition?
Go to Step 3. Faulty ignition coil, wire
harness, or other system
parts.
3 Fuel Injector Circuit Inspection :
1) Using sound scope, check each injector oper-
ating sound at engine cranking or idling.
Do all injectors make operating sound?
Go to Step 4. Check coupler connec-
tion and wire harness of
injector not making oper-
ating sound and injector
itself.
If OK, substitute a known-
good ECM (PCM) and
recheck.
4 Fuel Pressure Inspection :
1) Check fuel pressure referring to “TABLE B-3” in
this section.
Is check result satisfactory?
Go to Step 5. Repair or replace.
5 Fuel Injector Inspection :
1) Check fuel injector(s) referring to “Fuel Injector”
in Section 6E1.
Is check result satisfactory?
Go to Step 6. Replace.
6 Ignition Timing Inspection :
1) Check ignition timing referring to “Ignition Tim-
ing Check” in Section 6F1 or 6F2.
Is check result satisfactory?
Go to Step 7. Adjust or check system
related parts.
7 EGR System Inspection :
1) Check EGR system referring to “EGR System”
in Section 6E1.
Is check result satisfactory?
Go to Step 8. Repair or replace.
8 Fuel Level Sensor Inspection :
1) Check fuel level sensor referring to “DTC
P0460 Diag. Flow Table” in this section.
Is check result satisfactory?
Go to Step 9. Repair or replace.
9 Check engine mechanical parts or system which
can cause engine rough idle or poor performance.
• Engine compression (Refer to “Compression
Check” in Section 6A1 or 6A4).
• Valve lash or lash adjuster (Refer to “Valve
Lash (Clearance)” in Section 6A1 or “Cam-
shafts and Valve Lash Adjusters” in Section
6A4).
• Valve timing (Refer to “Timing Belt and Belt
Tensioner” in Section 6A1 or “2ND Timing
Chain and Chain Tensioner” in Section 6A4).
Are they in good condition?
Check wire harness
and connection of
ECM (PCM) ground,
ignition system and
fuel injector for inter-
mittent open and short. Repair or replace.