Suzuki Engine 2002 GRAND VITARA SQ625, Service Manual

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6-1-80 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H25 ENGINE)
• Intake air temperature : between –14°C and 70°C (6.8°F and 158°F)
• Atmospheric pressure : higher than 560 mmHg (Altitude : lower than 2790 m (9150 ft))
• Following DTCs are not detected : P0110 (No.23, 25), P0335, P0460, P1450 and P1451
1) With ignition switch OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC by using scan tool if any.
3) Start engine and warm up to normal operating temperature.
4) Increase vehicle speed to 56 km/h (35 mph) or more.
5) Keep above vehicle speed for 5 min. (Throttle valve operating is kept constant in this step.)
6) Increase vehicle speed to 80 – 100 km/h (50 – 60 mph). (engine speed; 2500 – 3000 r/min.)
7) Keep above vehicle speed for 1 min. (Throttle valve operating is kept constant in this step.)
8) Release accelerator pedal and with engine brake applied, keep vehicle coasting and then stop vehicle.
9) Check DTC and pending DTC by using scan tool.
DTC TROUBLESHOOTING
WARNING:
• When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and very careful during to avoid occurrence of an accident.
• Road test, should be carried out with 2 person, a driver and tester, on a level road.
Step Action Yes No
1 Was “Engine Diag. Flow Table” performed? Go to Step 2. Go to “Engine Diag. Flow
Table”.
2 HO2S Voltage check :
1) With ignition switch OFF, install scan tool.
2) Start engine and check “O2S B1 S2” (HO2S
voltage) displayed on scan tool while
repeating racing engine.
Does the voltage deflect between 0 – 0.25 V
and 0.35 – 2.0 V?
Intermittent trouble.
If OK, substitute a known-
good ECM (PCM) and
recheck. Go to Step 3.
3 Wire Harness check :
1) Check “RED/BLK” and “GRY/YEL” wire.
Are they in good condition?
Go to Step 4. Repair or replace.
4 Fuel Injector Circuit check :
1) Check fuel injector circuit referring to “Table
B-2” in this section.
Is it in good condition?
Go to Step 5. Repair or replace.
5 Fuel Injection inspection :
1) Inspect fuel injectors (No.1, 3, 5) referring to
“Fuel Injector” in Section 6E2.
Are they in good condition?
Go to Step 6. Faulty fuel injector(s).
6 Fuel Pressure inspection :
1) Check fuel pressure referring to following
“Table B-3” in this section.
Is fuel pressure within specification?
Replace HO2S and
recheck.
If DTC P0136 detected,
substitute a known-good
ECM (PCM) and recheck. Repair or replace.