1999 SUZUKI GRAND VITARA Oxygen sensor

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-73
1) Connect scan tool with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data in ECM memory by using scan
tool and start engine.
3) Increase vehicle speed to 55 km/h (40 mph) or more.
4) Keep driving above vehicle speed till engine is warmed up completely (Changed of vehicle speed is permit-
ted in this step).
5) Keep driving 50 – 60 km/h (30 – 40 mph) for 8 min. or more.
6) Stop vehicle and check if pending DTC exists by using scan tool. If not, check if oxygen sensor heater moni-
toring test has completed by using scan tool. If not in both of above checks (i.e., no pending DTC and oxy-
gen sensor heater monitoring test not completed), check vehicle conditions (environmental) and repeat
Steps 3) through 6).
TROUBLESHOOTING
NOTE:
Check to make sure that following conditions are satisfied when using this “DTC CONFIRMATION
PROCEDURE”.
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : – 8 – 110°C (18 – 230°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)
Step Action Yes No
1 Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 HO2S-2 output voltage check :
1) Connect scan tool to DLC with ignition
switch OFF.
2) Drive vehicle about 35 mph, 55 km/h for 2
min. or more.
3) Stop vehicle and check HO2S-2 output volt-
age displayed on scan tool while repeating
racing engine.
Is over and below 0.3 V indicated?Go to Step 4. Go to Step 3.
3 HO2S-2 check :
1) With ignition switch OFF, disconnect HO2S-
2 coupler.
2) Connect voltmeter between “2” and “1” of
HO2S-2 coupler.
3) Start engine and check voltmeter while
repeating racing engine.
Is over and below 0.3 V indicated?“RED/YEL” or “GRY/YEL”
circuit open/short.
If wire and connection are
OK, substitute a known-
good ECM (PCM) and
recheck.Replace HO2S-2.
4 Short term fuel trim check :
1) Run engine at 2000 r/min. for 60 sec.
2) With engine idling, check short term fuel
trim displayed on scan tool.
Is it within – 20 to +20 %?Intermittent trouble or
faulty ECM (PCM).
Check for intermittent
referring to “INTERMIT-
TENT AND POOR CON-
NECTION” in Section 0A.Go to DTC P0174/P0175
Diag. Flow Table.

6-1-74 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0161 HO2S-2 (Bank 2) Heater Circuit Malfunction
WIRING DIAGRAM
Refer to DTC P0156.
DTC DETECTING CONDITION AND TROUBLE AREA
DTC CONFIRMATION PROCEDURE
1) Connect scan tool with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data in ECM memory by using scan
tool and start engine.
3) Increase vehicle speed to 50 – 60 km/h (30 – 40 mph).
4) Keep driving above vehicle speed for 5 min. (Change of vehicle speed is permitted in this step).
5) Stop vehicle and check if pending DTC exists by using scan tool. If not, check if oxygen sensor heater moni-
toring test has completed by using scan tool. If not in both of above checks (i.e., no pending DTC and oxy-
gen sensor heater monitoring test not completed), check vehicle conditions (environmental) and repeat
Steps 3) through 5).DTC DETECTING CONDITION TROUBLE AREA
Following condition is detected when HO2S-2 heater operates (2
driving cycle detection logic).
• Current of HO2S-2 heater is more than 11.4 A or less than 0.32 A,
or
• Voltage of HO2S-2 heater is more than 13.8 V or less than 8.7 V.HO2S-2 heater or its circuit
ECM (PCM)
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that following conditions are satisfied when using this “DTC CONFIRMATION
PROCEDURE”.
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : – 8 – 110°C (18 – 230°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)

6-1-76 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0171/P0172 Fuel System Too Lean/Rich (Bank 1)
DTC DETECTING CONDITION AND POSSIBLE CAUSE
DTC CONFIRMATION PROCEDURE
1) Connect scan tool to DLC with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data by using scan tool and warm up
engine completely.
3) Increase vehicle speed to 50 – 60 km/h (30 – 40 mph).
4) Keep driving above vehicle speed for 3 min. or more.
5) Stop vehicle and check pending DTC by using scan tool.DTC DETECTING CONDITION TROUBLE AREA
When running after engine warmed (2 driving cycle
detection logic).
• Short term fuel trim exceeding 15 % or long term fuel
trim exceeding 20 % and total trim exceeding 43 % is
detected.
– Fuel system too lean
• Short term fuel trim less than – 11 % or long term fuel
trim less than – 11 % and total trim less than – 30 % is
detected.
– Fuel trim too rich• Vacuum leaks (air inhaling)
• Exhaust gas leakage
• Fuel pressure out of specification
• Heated oxygen sensor malfunction
• EGR system malfunction
• MAF sensor poor performance
• ECT sensor poor performance
• Fuel level sensor.
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that following conditions are satisfied when using this “DTC CONFIRMATION
PROCEDURE”.
Intake air temp. at start : – 8 – 60°C (18 – 140°F)
Engine coolant temp. at start : – 8 – 95°C (18 – 203°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : 110°C (230°F) or lower

6-1-78 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0174/P0175 Fuel System Too Lean/Rich (Bank 2)
DTC DETECTING CONDITION AND POSSIBLE CAUSE
DTC CONFIRMATION PROCEDURE
1) Connect scan tool to DLC with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data by using scan tool and warm up
engine completely.
3) Increase vehicle speed to 50 – 60 km/h (30 – 40 mph).
4) Keep driving above vehicle speed for 3 min. or more.
5) Stop vehicle and check pending DTC by using scan tool.DTC DETECTING CONDITION TROUBLE AREA
When running after engine warmed (2 driving cycle
detection logic).
• Short term fuel trim exceeding 15 % or long term fuel
trim exceeding 20 % and total trim exceeding 43 % is
detected.
– Fuel system too lean
• Short term fuel trim less than – 11 % or long term fuel
trim less than – 11 % and total trim less than – 30 % is
detected.
– Fuel trim too rich• Vacuum leaks (air inhaling)
• Exhaust gas leakage
• Fuel pressure out of specification
• Heated oxygen sensor malfunction
• EGR system malfunction
• MAF sensor poor performance
• ECT sensor poor performance
• Fuel level sensor.
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that following conditions are satisfied when using this “DTC CONFIRMATION
PROCEDURE”.
Intake air temp. at start : – 8 – 60°C (18 – 140°F)
Engine coolant temp. at start : – 8 – 95°C (18 – 203°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : 110°C (230°F) or lower

6-1-94 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0420 Catalyst System Efficiency Below Threshold (Bank 1)
SYSTEM DIAGRAM
CIRCUIT DESCRIPTION
Exhaust oxygen concentration at the pre-catalyst and the post-catalyst of WU-TWC is detected from HO2S-1
and HO2S-2 respectively and accordingly ECM (PCM) controls the closed loop which then controls the fuel
injection volume. (Refer to Section 6E2.) While the above control is going on and if WU-TWC is in good condi-
tion, the output voltage of HO2S-2 is maintained at specified level. As WU-TWC becomes deteriorated, even
when the above control is going on, the exhaust gas which has passed WU-TWC then passes HO2S-2 at the
exhaust oxygen concentration similar to that of the pre-catalyst without being oxygenated or converted. Thus,
waveforms of HO2S-1 and HO2S-2 output voltages become alike. ECM (PCM) judges deterioration of WU-TWC
by comparing waveforms of HO2S-1 and HO2S-2.
DTC DETECTING CONDITION AND TROUBLE AREA
1. HO2S-1 (Bank-1) 4. TWC
2. HO2S-2 (Bank-1) 5. ECM (PCM)
3. WU-TWC
DTC DETECTING CONDITION TROUBLE AREA
While running under conditions described for DTC CON-
FIRMATION PROCEDURE, output waveform of HO2S-1
becomes similar to that of HO2S-2.
(2 driving cycle detection logic)• Exhaust gas leakage
• Warm up three way catalytic converter
• Heated oxygen sensor – 2 or its circuit
•ECM (PCM)

6-1-96 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0430 Catalyst System Efficiency Below Threshold (Bank 2)
SYSTEM DIAGRAM
CIRCUIT DESCRIPTION
Exhaust oxygen concentration at the pre-catalyst and the post-catalyst of WU-TWC is detected from HO2S-1
and HO2S-2 respectively and accordingly ECM (PCM) controls the closed loop which then controls the fuel
injection volume. (Refer to Section 6E2.) While the above control is going on and if WU-TWC is in good condi-
tion, the output voltage of HO2S-2 is maintained at specified level. As WU-TWC becomes deteriorated, even
when the above control is going on, the exhaust gas which has passed TWC then passes HO2S-2 at the
exhaust oxygen concentration similar to that of the pre-catalyst without being oxygenated or converted. Thus,
waveforms of HO2S-1 and HO2S-2 output voltages become alike. ECM (PCM) judges deterioration of WU-TWC
by comparing waveforms of HO2S-1 and HO2S-2.
DTC DETECTING CONDITION AND TROUBLE AREA
1. HO2S-1 (Bank-2) 4. TWC
2. HO2S-2 (Bank-2) 5. ECM (PCM)
3. WU-TWC
DTC DETECTING CONDITION TROUBLE AREA
While running under conditions described for DTC CON-
FIRMATION PROCEDURE, output waveform of HO2S-1
becomes similar to that of HO2S-2.
(2 driving cycle detection logic)• Exhaust gas leakage
• Warm up three way catalytic converter
• Heated oxygen sensor – 2 or its circuit
•ECM (PCM)

ENGINE MECHANICAL (H27 ENGINE) 6A2-1
6A2
SECTION 6A2
ENGINE MECHANICAL (H27 ENGINE)
CONTENTS
On-Vehicle Service........................................6A2-2
Throttle Body and Intake Manifold .............. 6A2-2
Exhaust Manifold ......................................... 6A2-9
LH (No.1) Bank 2nd Timing Chain
and Chain Tensioner ................................. 6A2-13
Camshaft and Valve Lash Adjuster ........... 6A2-14
Valves and Cylinder Heads ....................... 6A2-17
Piston, Piston Rings, Connecting Rodsand Cylinders ............................................ 6A2-21
Unit Repair Overhaul .................................. 6A2-26
Engine Assembly ...................................... 6A2-26
Main Bearings, Crankshaft
and Cylinder Block .................................... 6A2-30
Special Tool ................................................. 6A2-36

WARNING:
For vehicles equipped with Supplemental Restraint (Air Bag) System:
Service on and around the air bag system components or wiring must be performed only by an
authorized SUZUKI dealer. Refer to “Air Bag System Components and Wiring Location View” under
“General Description” in air bag system section in order to confirm whether you are performing ser-
vice on or near the air bag system components or wiring. Please observe all WARNINGS and “Ser-
vice Precautions” under “On-Vehicle Service” in air bag system section before performing service
on or around the air bag system components or wiring. Failure to follow WARNINGS could result in
unintentional activation of the system or could render the system inoperative. Either of these two
conditions may result in severe injury.
Technical service work must be started at least 90 seconds after the ignition switch is turned to the
“LOCK” position and the negative cable is disconnected from the battery. Otherwise, the system
may be activated by reserve energy in the Sensing and Diagnostic Module (SDM).
NOTE:
For the descriptions (items) not found in this section, refer to the same section of service manual
mentioned in the FOREWORD of this manual.
Whether following systems (parts) are used in the particular vehicle or not depends on specifica-
tions. Be sure to bear this in mind when performing service work.
–EGR valve
–Warm up three way catalytic converter
–Heated oxygen sensor(s)
–Three way catalytic converter
–CKP sensor
–MAP sensor

ENGINE MECHANICAL (H27 ENGINE) 6A2-9
26) Upon completion of installation, verify that there is no fuel
leakage at each connection according to procedure
described in Section 6.
Exhaust Manifold
REMOVAL
1) Disconnect negative (–) cable at battery.
2) Remove air cleaner upper case and intake air hose if right
side exhaust manifold is removed.
3) Detach couplers from their bracket and disconnect oxygen
sensor lead wires at couplers. WARNING:
To avoid danger of being burned, do not service exhaust
system while it is still hot. Service should be performed
after system has cooled off.
1. Left (No.1) exhaust manifold
Right (No.2) exhaust manifold
2. Exhaust manifold cover
3. Exhaust No.1 pipe
A. Without WU-TWC
B. With WU-TWC
1. HO2S-1 (Green connector)
2. HO2S-2 (Black connector)