Suzuki Engine 2002 GRAND VITARA SQ420 Service Manual page 90

TROUBLESHOOTING (DTC P0300/P0301/P0302/P0303/P0304)
Step
1 Was "Engine Diag. Flow Table" performed?
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?
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?
4 Fuel Pressure Inspection :
1) Check fuel pressure referring to "TABLE B-3" in
this section.
Is check result satisfactory?
5 Fuel Injector Inspection :
1) Check fuel injector(s) referring to "Fuel Injector"
in Section 6E1.
Is check result satisfactory?
6 Ignition Timing Inspection :
1) Check ignition timing referring to "Ignition Tim-
ing Check" in Section 6F1 or 6F2.
Is check result satisfactory?
7 EGR System Inspection :
1) Check EGR system referring to "EGR System"
in Section 6E1.
Is check result satisfactory?
8 Fuel Level Sensor Inspection :
1) Check fuel level sensor referring to "DTC
P0460 Diag. Flow Table" in this section.
Is check result satisfactory?
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?
ENGINE GENERAL INFORMATION AND DIAGNOSIS (G16/J20 ENGINES) 6-85
Action Yes
Go to Step 2.
Go to Step 3.
Go to Step 4.
Go to Step 5.
Go to Step 6.
Go to Step 7.
Go to Step 8.
Go to Step 9.
Check wire harness
and connection of
ECM (PCM) ground,
ignition system and
fuel injector for inter-
mittent open and short.
No
Go to "Engine Diag. Flow
Table".
Faulty ignition coil, wire
harness, or other system
parts.
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.
Repair or replace.
Replace.
Adjust or check system
related parts.
Repair or replace.
Repair or replace.
Repair or replace.