Page 217 of 557

ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-61
Usual driving: Driving at 30 – 40 mph, 50 – 60 km/h including short stop according to traffic signal. (under driving condition other than high-load,
high-engine speed, rapid accelerating and decelerating)1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11)and 50 mph
(80 km / h)
Above 20 mph
(32 km / h) Usual driving
DTC CONFIRMATION PROCEDURE
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic accident
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.
1) Turn ignition switch OFF.
Clear DTC with ignition switch ON, check vehicle and environmental condition for:
–Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
–Intake air temp.: –10C, 14F or higher
–No exhaust gas leakage and loose connection
2) Warm up engine to normal operating temperature.
3) Drive vehicle under usual driving condition for 5 min. and check HO2S-2 output voltage and “short term fuel
trim” with “Data List” mode on scan tool, and write it down.
4) Stop vehicle (don’t turn ignition switch OFF).
5) Increase vehicle speed to higher than 20 mph, 32 km / h and then stop vehicle.
6) Repeat above steps 5) 4 times.
7) Increase vehicle speed to about 50 mph (80 km / h) in 3rd gear or 2 range.
8) Release accelerator pedal and with engine brake applied, keep vehicle coasting (fuel cut condition) for 10sec.
or more.
9) Stop vehicle (don’t turn ignition switch OFF) and run engine at idle for 2 min.
After this step 9), if “Oxygen Sensor Monitoring TEST COMPLETED” is displayed in “READINESS TESTS”
mode and DTC is not displayed in “DTC” mode, confirmation test is completed.
If “TEST NOT COMPLTD” is still being displayed, proceed to next step 10).
10) Drive vehicle under usual driving condition for 10 min. (or vehicle is at a stop and run engine at idle for 10 min.
or longer)
11) Stop vehicle (don’t turn ignition switch OFF). Confirm test results according to “Test Result Confirmation Flow
Table” in “DTC CONFIRMATION PROCEDURE” of DTC P0420.
Page 218 of 557
6-1-62 ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13)
INSPECTION
STEPACTIONYESNO
1Was “ENGINE DIAG. FLOW TABLE” performed?Go to Step 2.Go to “ENGINE DIAG.
FLOW TABLE”.
2Check exhaust system for leakage, loose
connection and damage.
Is it good condition?Go to Step 3.Repair or replace.
3Check HO2S-2 and Its Circuit.
Was HO2S-2 output voltage indicated on scan
tool in step 3) of DTC confirmation test less
than 1.275 V?Go to Step 4.“G” or “R” circuit open or
HO2S-2 malfunction.
4Check Short Term Fuel Trim.
Did short term fuel trim very within –20 – + 20%
range in step 3) of DTC confirmation test?Check “R” and “G” wire
for open and short, and
connection for poor
connection. If wire and
connection are OK,
replace HO2S-2.Check fuel system. Go
to DTC P0171 / P0172
Diag. Flow Table.
Page 219 of 557
ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-63
To other sensor
Main
fuseIgnition
switch
Heater
To HO2S-1
heater
DTC P0141 HEATED OXYGEN SENSOR (HO2S) HEATER CIRCUIT
MALFUNCTION (SENSOR-2)
CIRCUIT DESCRIPTION
DTC DETECTING CONDITIONPOSSIBLE CAUSE
DTC will set when A or B condition it met.
A. Low voltage at terminal C02-4 for specified time after engine
start or while engine running at high load.
B. High voltage at terminal C02-4 while engine running under other
than above condition.
2 driving cycle detection logic, continuous monitoring.HO2S-2 heater circuit open or shorted
to ground
ECM (PCM) malfunction
DTC CONFIRMATION PROCEDURE
1) Turn ignition switch OFF once and then ON.
2) Clear DTC, start engine and warm up engine to normal operating temperature.
3) Keep it at 2000 r / min for 2 min.
4) Check pending DTC in “ON BOARD TEST” or “PENDING DTC” mode and DTC in “DTC” mode.
Page 220 of 557

6-1-64 ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13)
Fig. 1 for Step 2
INSPECTION
STEPACTIONYESNO
1Was “ENGINE DIAG. FLOW TABLE” performed?Go to Step 2.Go to “ENGINE DIAG.
FLOW TABLE”.
2Check HO2S-2 Heater and Its Circuit.
1) Warm up engine to normal operating temperature.
2) Stop engine.
3) Turn ignition switch ON and check voltage at
terminal C02-4 See Fig. 1. Voltage should be
over 10 V.
4) Start engine, run it at idle and check voltage at the
same terminal after 1 min. from engine start.
Voltage should be below 1.9 V.
Are check result as specified?Intermittent trouble.
Check for intermittent
referring to
“Intermittent and
Poor Connection”
in Section 0A.Go to Step 3.
3Check Heater or Sensor-2.
1) Disconnect HO2S-2 coupler with ignition switch
OFF.
2) Check for proper connection to HO2S-2 at “B/W”
and “Lg / B” wire terminals.
3) If OK, then check heater resistance.
Is it 11.7 – 14.3 Ω at 20C, 68F?“Lg / B” wire open or
shorted to ground or
poor connection at
C02-4. If wire and
connection are OK,
substitute a
known-good ECM
(PCM) and recheck.Replace HO2S-2.
Page 221 of 557

ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-65
Ignition
switch
Main
fuseMain relay
To ignition
switchTo other sensor Relay boxNo.1 injector
No.2 injector
No.3 injector
No.4 injector Fuse box
Signal to decrease amount of fuel injection
Signal to increase amount of fuel injection
High voltage
Low voltage
A / F mixture
becomes
richerOxygen
concentration
decreases
A / F mixture Oxygen
Fuel injectorSensed
information
A / F mixture
Exhaust gas
becomes
leanerconcentration
increases
DTC P0171 FUEL SYSTEM TOO LEAN
DTC P0172 FUEL SYSTEM TOO RICH
CIRCUIT DESCRIPTION
DTC DETECTING CONDITIONPOSSIBLE CAUSE
When following condition occurs while engine running under
closed loop condition.
–Air / fuel ratio too lean
Total fuel trim (short and long terms added) is
more than 30%
or
–Air / fuel ratio too rich
(Total fuel trim is less than –30%)
2 driving cycle detection logic, continuous monitoring.Vacuum leaks (air drawn in).
Exhaust gas leakage.
Heated oxygen sensor-1 circuit
malfunction.
Fuel pressure out of specification.
Fuel injector malfunction (clogged or
leakage).
MAP sensor poor performance.
ECT sensor poor performance.
IAT sensor poor performance.
TP sensor poor performance.
EVAP control system malfunction.
PCV valve malfunction.
Page 222 of 557

6-1-66 ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13)
DTC CONFIRMATION PROCEDURE
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic accident
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.
1) Turn ignition switch OFF.
2) Clear DTC with ignition switch ON.
3) Check vehicle and environmental condition for:
–Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
–Intake air temp.: between –10C and 80C (14F and 176F)
4) Start engine and drive vehicle under usual driving condition (described in DTC confirmation procedure of DTC
P0136) for 5 min. or longer and until engine is warmed up to normal operating temperature.
5) Keep vehicle speed at 30 – 40 mph, 50 – 60 km / h in 5th gear or “D” range for 5 min. or more.
6) Stop vehicle (do not turn ignition switch OFF).
7) Check pending DTC in “ON BOARD TEST” or “PENDING DTC” mode and DTC in “DTC” mode.
Page 223 of 557

ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13) 6-1-67
INSPECTION
STEPACTIONYESNO
1Was “ENGINE DIAG. FLOW TABLE” performed?Go to Step 2.Go to “ENGINE
DIAG. FLOW
TABLE”.
2Is there DTC(s) other than fuel system
(DTC P0171 / P0172)?Go to applicable
DTC Diag. Flow
Table.Go to Step 3.
3Check HO2S-1 Output Voltage.
1) Connect scan tool to DLC with ignition switch OFF.
2) Warm up engine to normal operating temperature and keep
it at 2000 r / min. for 60 sec.
3) Repeat racing engine (Repeat depressing accelerator pedal
5 to 6 times continuously and take foot off from pedal to
enrich and enlean A / F mixture). See Fig. 1.
Does HO2S-1 output voltage deflect between below 0.3 V and
over 0.6 V repeatedly?Go to Step 4.Go to DTC
P0130 Diag.
Flow Table
(HO2S-1 circuit
check).
4Check Fuel Pressure (Refer to section 6E2 for details).
1) Release fuel pressure from fuel feed line.
2) Install fuel pressure gauge.
3) Check fuel pressure. See Fig. 2.
With fuel pump operating
and engine at stop : 270 – 310 kPa, 2.7 – 3.1 kg / cm
2,
38.4 – 44.0 psi.
At specified idle speed : 200 – 240 kPa, 2.0 – 2.4 kg / cm
2,
28.4 – 34.1 psi.
Is measured value as specified?
Go to Step 5.Go to Diag. Flow
Table B-3 Fuel
Pressure Check.
5Check Fuel Injectors and Circuit.
1) Using sound scope (1) or such, check operating sound of
each injector (2) when engine is running. Cycle of operating
sound should vary according to engine speed. See Fig. 3.
If no sound or an unusual sound is heard, check injector
circuit (wire or coupler) or injector.
2) Turn ignition switch OFF and disconnect a fuel injector
connector.
3) Check for proper connection to fuel injector at each terminal.
See Fig. 4.Go to Step 6.Check injector
circuit or replace
fuel injector(s).
4) If OK, then check injector resistance.
Injector Resistance: 12 – 13 ohm at 20C (68F)
5) Carry out steps 1) and 3) on each injector.
6) Check each injector for injected fuel volume referring to
Section 6E2. See Fig. 5.
Injected Fuel Volume: 38 – 48 cc / 15 sec 1.28 /
1.34 – 1.62 / 1.69 US / Imp.oz / 15 sec)
7) Check each injector for fuel leakage after injector closed.
Fuel Leakage: Less than 1 drop / min.
Is check result in step 1) and 3) to 7) satisfactory?
6Check EVAP Canister Purge Valve.
1) Disconnect purge hose (1) from EVAP canister.
2) Place finger against the end of disconnected hose.
3) Check that vacuum is not felt there when engine is cool and
running at idle. See Fig. 6.
Is vacuum felt?Check EVAP
control system
(See Section
6E2).Go to Step 7.
7Check intake manifold absolute pressure sensor for
performance (See DTC P0105 Diag. Flow Table).
Is it in good condition?Go to Step 8.Repair or
replace.
Page 224 of 557
6-1-68 ENGINE GENERAL INFORMATION AND DIAGNOSIS (SFI FOR G13)
Fig. 1 for Step 3 Fig. 2 for Step 4 Fig. 3 for Step 5
Fig. 4 for Step 5 Fig. 5 for Step 5 Fig. 6 for Step 6
1. Fuel delivery pipe
2. Fuel feed hose
3. Fuel pressure gauge &
3 way joint
STEPACTIONYESNO
8Check engine coolant temp. sensor for performance
(See Section 6E2).
Is it in good condition?Go to Step 9.Replace engine
coolant temp. sensor.
9Check intake air temp. sensor for performance
(See Section 6E2).
Is it in good condition?Go to Step 10.Replace intake air
temp. sensor.
10Check throttle position sensor for performance (See
Step 3 of DTC P0121 Diag. Flow Table).
Is it in good condition?Go to Step 11.Replace throttle
position sensor.
11Check PCV valve for valve clogging
(See Section 6E2).
Is it good condition?Substitute a known-
good ECM (PCM) and
recheck.Replace PCV valve.