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Toyota Corolla (2004+). Manual - part 61

05-136

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

05DIM-01

DTC

P0171

SYSTEM TOO LEAN (BANK 1)

DTC

P0172

SYSTEM TOO RICH (BANK 1)

CIRCUIT DESCRIPTION

The fuel trim is related to the feedback compensation value, not to the basic injection time. The fuel trim in-

cludes the short-term fuel trim and the long-term fuel trim.

The short-term fuel trim is the short-term fuel compensation used to maintain the air-fuel ratio at stoichio-

metric air-fuel ratio. The signal from the heated oxygen sensor indicates whether the air-fuel ratio is RICH

or LEAN compared to the stoichiometric air-fuel ratio. This variance triggers a reduction in the fuel volume

if the air-fuel ratio is RICH, and an increase in the fuel volume if it is LEAN.

The long-term fuel trim is the overall fuel compensation carried out in long-term to compensate for a continu-

al deviation of the short-term fuel trim from the central value, due to individual engine differences, wear over-

time and changes in the operating environment.

If both the short-term fuel trim and the long-term fuel trim are LEAN or RICH beyond a certain value, it is

detected as a malfunction and the MIL is illuminated.

DTC No.

DTC Detection Condition

Trouble Area

_ Air induction system

_ Injector blockage

_ Mass air flow sensor

_ Engine coolant temperature sensor

_ Fuel pressure

_ Gas leakage in exhaust system

When air-fuel ratio feedback is stable after warming up engine,

_ Open or short in heated oxygen sensor (bank 1, sensor 1)

P0171

fuel trim is considerably in error on LEAN side

circuit

(2 trip detection logic)

_ Heated oxygen sensor (bank 1, sensor 1)

_ Heated oxygen sensor heater (bank 1, sensor 1)

_ EFI relay

_ PCV valve and hose

_ PCV hose connection

_ ECM

_ Injector leak, blockage

_ Mass air flow sensor

_ Engine coolant temperature sensor

_ Ignition system

_ Fuel pressure

When air-fuel ratio feedback is stable after warming up engine,

_ Gas leakage in exhaust system

P0172

fuel trim is considerably in error on RICH side

_ Open or short in heated oxygen sensor (bank 1, sensor 1)

(2 trip detection logic)

circuit

_ Heated oxygen sensor (bank 1, sensor 1)

_ Heated oxygen sensor heater (bank 1, sensor 1)

_ EFI relay

_ ECM

HINT:

When DTC P0171 is recorded, the actual air-fuel ratio is on the LEAN side. When DTC P0172 is re-

corded, the actual air-fuel ratio is on the RICH side.

If the vehicle runs out of fuel, the air-fuel ratio is LEAN and DTC P0171 may be recorded. The MIL

then comes on.

If the total of the short-term fuel trim value and long-term fuel trim value is within

35 % (engine cool-

ant temperature is more than 75 fC (167fF)), the system is functioning normally.

05-137

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

MONITOR DESCRIPTION

+35 (%): Threshold at LEAN

1.35

Fuel compensation

1.0

amount

-35 (%): Threshold at RICH

0.65

A82386

Under the closed-loop fuel control, fuel injection amounts that deviate from the ECM’s estimated fuel

amount will cause a change in the long-term fuel trim compensation value. This long-term fuel trim is ad-

justed when there are persistent deviations in the short-term fuel trim values. And the deviation from a simu-

lated fuel injection amount by the ECM affects a smoothed fuel trim learning value which is the combination

of smoothed short-term fuel trim (fuel feedback compensation value) and smoothed long-term fuel trim

(learning value of the air-fuel ratio). When the smoothed fuel trim learning value exceeds the DTC threshold,

the ECM interprets this as a fault in the fuel system and sets a DTC.

Example:

The smoothed fuel trim leaning value is more than +35% or less than -35%, the ECM interprets this as a

fail in the fuel system.

MONITOR STRATEGY

P0171

Fuel system lean (bank 1)

Related DTCs

P0172

Fuel system rich (bank 1)

Main sensors

Heated oxygen sensor

Required sensors/components

Engine coolant temperature sensor, mass air flow sensor, crankshaft

Related sensors

position sensor

Frequency of operation

Continuous

Duration

10 seconds

MIL operation

2 driving cycles

Sequence of operation

None

05-138

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

TYPICAL ENABLING CONDITIONS

Specification

Item

Minimum

Maximum

The monitor will run whenever the follow-

See ”List of Disable a Monitor” (On page 05-25)

ing DTCs are not present

Battery voltage

11 V

Fuel system: Closed loop

13 seconds

One of the following condition is met:

(a) or (b)

(a) Engine speed

1,100 rpm

(b) Intake air amount per revolution

0.14 g/rev

TYPICAL MALFUNCTION THRESHOLDS

Detection Criteria

Threshold

Following condition is continue for 3 seconds (”a” or ”b”)

(a) Smoothed fuel trim learning value (lean)

35 % or more

(b) Smoothed fuel trim learning value (rich)

-35 % or less

WIRING DIAGRAM

Refer to DTC P0130 on page 05-101.

INSPECTION PROCEDURE

HINT:

Hand-held tester only:

Narrowing down the trouble area is possible by performing ”A/F CONTROL” ACTIVE TEST (heated oxygen

sensor or other trouble areas can be distinguished).

(a) Perform ACTIVE TEST using hand-held tester (A/F CONTROL).

HINT:

”A/F CONTROL” is the ACTIVE TEST which changes the injection volume to -12.5 % or +25 %.

(1)

Connect the hand-held tester to the DLC3 on the vehicle.

(2)

Turn the ignition switch ON.

(3)

Warm up the engine by running the engine speed at 2,500 rpm for approximately 90 seconds.

(4)

Select the item ”DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST / A/F CONTROL”.

(5)

Perform ”A/F CONTROL” with the engine in an idle condition (press the right or left button).

Result:

Heated oxygen sensor reacts in accordance with increase and decrease of injection volume

+25 %  rich output: More than 0.5 V,

-12.5 %  lean output: Less than 0.4 V

05-139

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

NOTICE:

There is a delay of few seconds in the sensor 1 (front sensor) output, and there is about 20 seconds

delay at maximum in the sensor 2 (rear sensor).

Output voltage of heated oxygen

Mainly suspect

sensor (sensor 1: front sensor)

sensor (sensor 2: rear sensor)

trouble area

Injection volume

+25 %

-12.5 %



Case 1

Output voltage

More than 0.5 V

Less than 0.4V

Injection volume

+25 %

-12.5 %

Sensor 1: front sensor

Output voltage

(sensor 1, heater, sensor 1

Case 2

circuit)

More than 0.5 V

No reaction

Less than 0.4V

Injection volume

+25 %

-12.5 %

Sensor 2: rear sensor

-12.5 %

Output voltage

(sensor 2, heater, sensor 2

Case 3

circuit)

More than 0.5 V

No reaction

Less than 0.4V

Injection volume

+25 %

Extremely rich or lean actual

-12.5 %

air-fuel ratio

Case 4

Output voltage

(Injector, fuel pressure, gas

leakage in exhaust system,

No reaction

etc.)

The following of A/F CONTROL procedure enables the technician to check and graph the voltage outputs

of both the heated oxygen sensors.

For displaying the graph indication, enter ”ACTIVE TEST / A/F CONTROL / USER DATA”, then select ”O2S

B1S1 and O2S B1S2” by pressing ”YES” button and push ”ENTER” button before pressing ”F4” button.

HINT:

If different DTCs related to different systems that have terminal E2 as the ground terminal are output

simultaneously, terminal E2 may be open.

Read freeze frame data using the hand−held tester or the OBD II scan tool. Freeze frame data records

the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determin-

ing whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio

was lean or rich, etc. at the time of the malfunction.

A high heated oxygen sensor (sensor 1) voltage (0.5 V or more) could be caused by a rich air fuel mix-

ture. Check for conditions that would cause the engine to run rich.

A low heated oxygen sensor (sensor 1) voltage (0.4 V or less) could be caused by a lean air fuel mix-

ture. Check for conditions that would cause the engine to run lean.

05-140

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

CHECK AIR INDUCTION SYSTEM

(a) Check the air induction system for vacuum leaks.

NG REPAIR OR REPLACE AIR INDUCTION SYSTEM

CHECK CONNECTION OF PCV HOSE

NG REPAIR OR REPLACE PCV HOSE

INSPECT FUEL INJECTOR ASSY(INJECTION AND VOLUME) (See page 11-5)

NG REPLACE FUEL INJECTOR ASSY

(See page 11-10)

05-141

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

INSPECT MASS AIR FLOW SENSOR

(a) Remove the mas air flow sensor.

Air

(b) Inspect output voltage.

(1)

Apply battery voltage across terminals +B and E2G.

(2)

Connect the positive (+) tester prove to terminal VG,

THA

E2G

and negative (-) tester prove to terminal E2G.

(3)

Blow air into the mass air flow sensor, and check

that the voltage fluctuates.

(c)

Resistance inspection.

(1)

Measure the resistance between the terminals of

the intake air temperature sensor.

Standard:

Tester Connection

Temperature

Specified Condition

–20 fC (-4 fF)

13.6 to 18.4 kW

THA (M1-4) - E2 (M1-5)

20 fC (68 fF)

2.21 to 2.69 kW

60 fC (140 fF)

0.49 to 0.67 kW

(d) Reinstall the mas air flow sensor.

0.5

0.3

Acceptable

0.2

0.1

–20

100

(-4)

(32)

(80)

(104)

(140)(176)

(212)

TEMPERATUREfC(fF)

A60548

NG REPLACE MASS AIR FLOW SENSOR

05-142

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

INSPECT ENGINE COOLANT TEMPERATURE SENSOR(RESISTANCE)

(a) Remove the engine coolant temperature sensor.

Ohmmeter

(b) Measure the resistance between the terminals of the en-

gine coolant temperature sensor.

Standard:

Tester Connection

Temperature

Specified Condition

20fC (68fF)

2.32 to 2.59 kW

- 2

80fC (176fF)

0.310 to 0.326 kW

NOTICE:

Acceptable

If you checking the engine coolant temperature sensor in

water, be careful not to allow water to go into the terminals.

After checking, dry the sensor.

HINT:

0.5

Alternate procedure: Connect an ohmmeter to the installed en-

0.3

gine coolant temperature sensor and read the resistance. Use

0.2

an infrared thermometer to measure the engine temperature in

0.1

the immediate vicinity of the sensor. Compare these values to

the resistance/temperature graph. Change the engine temper-

-20

80 100

(-4)

(32)

(68)

(104)

(140)

(176)

(212)

ature (warm up or allow to cool down) and repeat the test.

S01196

S01699

TEMPERATURE fC (fF)

A81700

(c)

Reinstall the engine coolant temperature sensor.

NG REPLACE ENGINE COOLANT TEMPERATURE

SENSOR

CHECK FOR SPARK AND IGNITION (See page 18-1)

NG REPAIR OR REPLACE

CHECK FUEL PRESSURE (See page 11-5)

(a) Check the fuel pressure (high or low pressure).

NG CHECK AND REPLACE FUEL SYSTEM

CHECK FOR EXHAUST GAS LEAKAGE

NG REPAIR OR REPLACE EXHAUST GAS

LEAKAGE POINT (See page 15-2)

05-143

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

READ VALUE OF HAND-HELD TESTER OR OBD II SCAN TOOL(OUTPUT

VOLTAGE OF HEATED OXYGEN SENSOR (BANK 1 SENSOR 1))

(a) Connect the hand-held tester or the OBD II scan tool to the DLC3.

(b) Start the engine and push the hand-held tester or the OBD II scan tool main switch ON.

(c)

Select the item ”DIAGNOSIS / ENHANCED OBD II / DATA LIST / ALL / O2S B1S1”.

(d) Warm up the heated oxygen sensor with the engine speed at 2,500 rpm for approximately 90 seconds.

(e) Read the output voltage of the heated oxygen sensor during idling.

Heated oxygen sensor output voltage:

Alternates repeatedly between less than 0.4 V and more than 0.5 V (See the following table).

A85076

OK Go to step 17

INSPECT HEATED OXYGEN SENSOR(HEATER RESISTANCE)

Component Side

(a) Disconnect the H5 heated oxygen sensor connector.

Heated Oxygen Sensor

(b) Measure the resistance between the terminals of the

heated oxygen sensor connector.

Bank 1,

Standard:

Sensor 1

Tester Connection

Specified Condition

HT (H5-1) - +B (H5-2)

5 to 10 W at 20 fC (68 fF)

HT (H5-1) - E1 (H5-4)

10 kW or higher

(c)

Reconnect the heated oxygen sensor connector.

Front View

A79112

NG REPLACE HEATED OXYGEN SENSOR

05-144

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

INSPECT EFI RELAY

(a) Remove the EFI relay from the engine room R/B.

(b) Check for continuity in the EFI relay.

Standard:

Tester Connection

Specified Condition

1 - 2

Continuity

No continuity

3 - 5

Continuity

(Apply battery voltage to terminals 1 and 2)

(c)

Reinstall the EFI relay.

E34090

NG REPLACE EFI RELAY

05-145

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

CHECK HARNESS AND CONNECTOR(HEATED OXYGEN SENSOR - ECM)

Wire Harness Side:

(a)

Disconnect the H5 heated oxygen sensor connector.

Heated Oxygen Sensor Connector

(b)

Disconnect the E4 ECM connector.

(c)

Check the resistance between the wire harness side con-

Bank 1 Sensor 1

nectors.

Standard (Check for open):

Tester Connection

Specified Condition

HT (H5-1) - HT1A (E4-4)

Below 1 W

OX (H5-3) - OX1A (E4-23)

Front View

A79114

Standard (Check for short):

Tester Connection

Specified Condition

HT (H5-1) or HT1A (E4-4) - Body ground

10 kW or higher

OX (H5-3) or OX1A (E4-23) - Body ground

(d)

Reconnect the ECM connector.

(e)

Reconnect the heated oxygen sensor connector.

HT1A

OX1A

ECM Connector

A55007

Reference (Bank 1 Sensor 1 System Drawing):

ECM

EFI Relay

Heated Oxygen Sensor

From

EFI Fuse

Heater

HT1A

Battery

Sensor

OX1A

From

Duty

Terminal 6 of

Control

Ignition Switch

Ground Ground

A82244

NG REPAIR OR REPLACE HARNESS OR

CONNECTOR

05-146

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

REPLACE HEATED OXYGEN SENSOR

HINT:

Check the air induction system for vacuum leaks.

PERFORM CONFIRMATION DRIVING PATTERN

40seconds

Vehicle speed

or more

25mph

(40 km/h)

(F3)

Idling(F2)

(F4)

IG SW OFF

120 seconds

20 seconds

30 seconds

or more

(F1)

A09299

A83859

(a) Connect the hand-held tester to the DLC3. (F1)

(b) Switch the hand-held tester from the normal mode to the check mode (See page 05-11). (F1)

(c)

Start the engine and let it idle for 120 seconds or more. (F2)

(d) Drive the vehicle at 25 mph (40 km/h) or more for 40 seconds or more. (F3)

(e) Let the engine idle for 20 seconds or more. (F4)

(f)

Perform steps (d) and (e) at least 3 times.

HINT:

If a malfunction exists, the MIL will be illuminated on the multi-information display during step (f).

NOTICE:

If the conditions in this test are not strictly followed, detection of a malfunction will not occur. If you

do not have the hand-held tester, turn the ignition switch OFF after performing steps from (c) to (f),

then perform steps from (c) to (f) again.

05-147

DIAGNOSTICS

SFI SYSTEM (April, 2003)

READ OUTPUT DTC(DTC P0171 AND/OR P0172 ARE OUTPUT AGAIN)

(a) Connect the hand-held tester or the OBD II scan tool to the DLC3.

(b) Turn the ignition switch ON and push the hand-held tester or the OBD II scan tool main switch ON.

(c)

Select the item ”DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES”.

(d) Read the DTCs.

Result:

Display (DTC output)

Proceed to

”P0171 and/or P0172” are not output

”P0171 and/or P0172”

REPLACE ECM (See page 10-11)

AND PERFORM CONFIRMATION DRIVING PAT-

TERN (Refer to step 14)

CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST

NO CHECK FOR INTERMITTENT PROBLEMS

(See page 05-41)

YES

DTC IS CAUSED BY RUNNING OUT OF FUEL (DTCS P0171 AND/OR P0172)

PERFORM CONFIRMATION DRIVING PATTERN

HINT:

Clear all DTCs prior to performing the confirmation driving pattern. (Refer to step 14)

READ OUTPUT DTC(DTC P0171 AND/OR P0172 ARE OUTPUT AGAIN)

(a) Connect the hand-held tester or the OBD II scan tool to the DLC3.

(b) Turn the ignition switch ON and push the hand-held tester or the OBD II scan tool main switch ON.

(c)

Select the item ”DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES”.

(d) Read the DTCs.

Result:

Display (DTC output)

Proceed to

”P0171 and/or P0172”

”P0171 and/or P0172” are not output

Go to step 22

REPLACE HEATED OXYGEN SENSOR

05-148

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

PERFORM CONFIRMATION DRIVING PATTERN (See page 05-29)

HINT:

Clear all DTCs prior to performing the confirmation driving pattern. (Refer to step 14)

READ OUTPUT DTC(DTC P0171 AND/OR P0172 ARE OUTPUT AGAIN)

(a) Connect the hand-held tester or the OBD II scan tool to the DLC3.

(b) Turn the ignition switch ON and push the hand-held tester or the OBD II scan tool main switch ON.

(c)

Select the item ”DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES”.

(d) Read the DTCs.

Result:

Display (DTC output)

Proceed to

”P0171 and/or P0172” are not output

”P0171 and/or P0172”

REPLACE ECM (See page 10-11)

AND PERFORM CONFIRMATION DRIVING PAT-

TERN (Refer to step 14)

CONFIRM IF VEHICLE HAS RUN OUT OF FUEL IN PAST

NO CHECK FOR INTERMITTENT PROBLEMS

(See page 05-41)

YES

DTC IS CAUSED BY RUNNING OUT OF FUEL

05-149

DIAGNOSTICS

SFI SYSTEM (April, 2003)

059VJ-07

DTC

P0300

RANDOM/MULTIPLE CYLINDER MISFIRE

DETECTED

DTC

P0301

CYLINDER 1 MISFIRE DETECTED

DTC

P0302

CYLINDER 2 MISFIRE DETECTED

DTC

P0303

CYLINDER 3 MISFIRE DETECTED

DTC

P0304

CYLINDER 4 MISFIRE DETECTED

CIRCUIT DESCRIPTION

When a misfire occurs in the engine, hydrocarbons (HC) enter the exhaust in high concentrations. If this HC

concentration is high enough, there could be an increase in exhaust emissions levels. High concentrations

of HC passing through the catalyst also cause to temperature of the catalyst to increase, possibly damaging

the catalyst. To prevent this increase in the emissions and limit the possibility of thermal damage, the ECM

monitors the misfire rate. When the temperature of the catalyst reaches a point of thermal degradation, the

ECM will blink the MIL. For monitoring misfire, the ECM uses both the camshaft position sensor and crank-

shaft position sensor. The camshaft position sensor is used to identify misfiring cylinders and the crankshaft

position sensor is used to measure variations in the crankshaft rotation speed. The misfire counter incre-

ments when crankshaft rotation speed variations exceed threshold values.

The ECM illuminates the MIL if the misfiring rate exceeds a threshold value and could cause emissions dete-

rioration.

DTC No.

DTC Detection Condition

Trouble Area

F Open or short in engine wire

F Connector connection

P0300

Misfiring of random cylinders is detected

F Vacuum hose connection

F Ignition system

F Injector

F Fuel pressure

F Mass air flow sensor

F Engine coolant temperature sensor

P0301

F Compression pressure

P0302

Misfiring of each cylinder is detected

F Valve clearance

P0303

F Valve timing

P0304

F PCV hose connection

F PCV hose

F ECM

HINT:

When codes for a misfiring cylinder are recorded repeatedly but no random misfire code is recorded, it indi-

cates that the misfires have been detected and recorded at different times.

05-150

DIAGNOSTICS

- SFI SYSTEM (April, 2003)

Reference: Inspection using oscilloscope

With the engine idling, check the waveform between terminals #10 to #40 and E01 of the ECM connectors.

HINT:

The correct waveform is as shown.

Injector Signal Waveform

(Magnification)

20V

/Division

GND

1 msec./Division (Idling)

100 msec./Division (Idling)

Injection duration

A78423

MONITOR DESCRIPTION

Camshaft position sensor

ECM

Crankshaft position sensor

(36-2 teeth or 12 teeth)

A82387

The ECM illuminates the MIL if the misfiring rate exceeds a threshold value and could cause emissions dete-

rioration.

The ECM will illuminate the MIL when the percent misfire exceeds the specified limit per 1,000 engine revolu-

tions. One occurrence of excessive misfire during engine start will set the MIL. Four occurrences are required

to set the MIL 1,000 revolutions after engine start. (2 trip detection logic)

The MIL blinks when ”percent misfire causing catalyst damage” per 200 revolution met 3 times (1 time if the

engine rpm is in high speed range). (MIL blinks immediately)

Content .. 59 60 61 62 ..