2004 ISUZU TF SERIES mass air flow

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-81
TYPICAL SCAN DATA & DEFINITIONS (O2 SENSOR DATA)
Use the typical values table only after the On-Board Diagnostic System check has been completed, no DTC(s) were noted, and you have determined that the On-Board
Diagnostic are functioning properly.
Tech2 values from a properly running engine may be used for comparison with the engine you are diagnosing.
Condition : Vehicle stopping, engine running, air conditioning off & after warm-up (Coolant temperature approximately 80
C)

Tech 2
Parameter
Units Idle 2000rpm Definitions
1 Ignition Voltage V 10.0  14.5 10.0  14.5 This displays the system voltage measured by the ECM at ignition feed.
2 Engine Speed rpm 710  860 1950  2050 The actual engine speed is measured by ECM from the CKP sensor 58X signal.
3 Desired Idle
Speed rpm 750  770 750  770 The desired engine idle speed that the ECM commanding.
The ECM compensates for various engine loads.
4 Engine Coolant
Temperature
C or
F 80  90 (
C) 80  90 (
C) The ECT is measured by ECM from ECT sensor output voltage.
When the engine is normally warm upped, this data displays approximately 80 °C or
more.
5 Start Up ECT
(Engine Coolant
Temperature)
C or
F Depends on ECT
at start-up
Depends on ECT
at start-up
Start-up ECT is measured by ECM from ECT sensor output voltage when engine is
started.
6 Throttle Position % 0 4  6 Throttle position operating angle is measured by the ECM from throttle position
output voltage.
This should display 0% at idle and 99  100% at full throttle.
7 Throttle Position
Sensor V 0.4  0.7 0.6  0.8 The TPS output voltage is displayed.
This data is changing by accelerator operating angle.
8 Mass Air Flow g/s 5.0  8.0 13.0  16.0 This displays intake air amount.
The mass air flow is measured by ECM from the MAF sensor output voltage.
9 Air Fuel Ratio 14.7:1 14.7:1 This displays the ECM commanded value. In closed loop, this should normally be
displayed around 14.2:1  14.7:1.
10 Engine Load % 2  7 8  15 This displays is calculated by the ECM form engine speed and MAF sensor reading.
Engine load should increase with an increase in engine speed or air flow amount.
11 B1 Fuel System
Status Open Loop/ Close
Loop Close Loop Close Loop
12 B2 Fuel System
Status Open Loop/ Close
Loop Close Loop Close Loop
When the engine is first started the system is in "Open Loop" operation.
In "Open Loop", the ECM ignores the signal from the oxygen sensors.
When various conditions (ECT, time from start, engine speed & oxygen sensor
output) are met, the system enters "Closed Loop" operation.
In "Closed Loop", the ECM calculates the air fuel ratio based on the signal from the
oxygen sensors.
13 B1S1 O2 Sensor
(Bank1 Sensor 1)
mV 50  950 50 950
14 B2S1 O2 Sensor
(Bank2 Sensor 1)
mV 50  950 50  950
This displays the exhaust oxygen sensor output voltage.
Should fluctuate constantly within a range between 10mV (lean exhaust) and
1000mV (rich exhaust) while operating in closed loop.
15 B1 O2 Sensor
Ready (Bank 1)
Yes/No Yes Yes
16 B2 O2 Sensor
Ready (Bank 2)
Yes/No Yes Yes
This displays the status of the exhaust oxygen sensor.
This display will indicate "Yes" when the ECM detects a fluctuating oxygen sensor
output voltage sufficient to allow closed loop operation.
This will not occur unless the oxygen sensor is warmed up.
17 B1 Long Term
Fuel Trim (Bank
1)
% -10  20 -10  20
18 B2 Long Term
Fuel Trim (Bank
2)
% -10  20 -10  20
The long term fuel trim is delivered from the short term fuel term values and
represents a long term correction of fuel delivery for bank in question.
A value of 0% indicates that fuel delivery requires no compensation to maintain the
ECM commanded air fuel ratio.
A negative value indicates that the fuel system is rich and fuel delivery is being
reduced (decreased injector pulse width).
A positive value indicates that a lean condition exists and the ECM is compensating
by add fuel (increased injector pulse width).
Because long term fuel trim tends to follow short term fuel trim, a value in the
negative range due to canister purge at idle should not be considered unusual.
Excessive long term fuel trim values may indicate an rich or lean condition.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-131

Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P0101 B Mass Air Flow Sensor Circuit
Range/Performance 1. No DTC relating to barometer sensor, TPS,
CMP sensor, CKP sensor and MAF sensor
(low input & high input).
2. Engine speed is between 2800rpm and
4500rpm.
3. Throttle position sensor output voltage is
between 1V and 3V.
4. Intake air temperature is between -14
C and
70
C.
5. Air flow amount below 0.04g/s (small air) or
more than 177g/s (large air). Above
conditions are met for 3 seconds. No fail-safe function. Air flow amount is more than
0.04g/s or below 177g/s. 1. Air intake is obstructed.
2. Sensor signal circuit short to voltage circuit.
3. MAF sensor malfunction.
4. Electrical interference.
5. ECM malfunction. B20/
B39 - P0102 A Mass Air Flow Sensor Circuit
Low Input MAF sensor output voltage is below 0.3V. MAF sensor output voltage is
more than 0.3V. 1. Sensor power supply circuit open circuit.
2. Sensor signal circuit open or short to ground
circuit.
3. Poor connector connection.
4. MAF sensor malfunction.
5. ECM malfunction. B20 -
61
P0103 A Mass Air Flow Sensor Circuit
High Input MAF sensor output voltage is more than 4.9V. The ECM uses default mass
air flow value based on IAC
valve position, throttle position,
barometer pressure and
engine speed.
MAF sensor output voltage is
below 4.9V. 1. Sensor signal circuit short to voltage circuit.
2. Sensor ground circuit open or short to voltage
circuit.
3. MAF sensor malfunction.
4. ECM malfunction. B20/
B39 P0113/
P0123/
P0341/
P0342
P0112 A Intake Air Temperature Sensor
Low Input IAT sensor output voltage is below 0.08V. IAT sensor output voltage is
more than 0.08V. 1. Sensor signal circuit short to ground circuit.
2. IAT sensor malfunction.
3. ECM malfunction. A19 -
23

P0113 A Intake Air Temperature Sensor
High Input IAT sensor output voltage is more than 4.9V. The ECM use 40
C conditions
as substitute.
IAT sensor output voltage is
below 4.9V. 1. Sensor signal circuit open or short to voltage
circuit.
2. Sensor ground circuit open or short to voltage
circuit.
3. Poor connector connection
4. IAT sensor malfunction.
5. ECM malfunction. A19/
B39 P0103/
P0123/
P0341/
P0342

6E-132 3.5L ENGINE DRIVEABILITY AND EMISSIONS Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P0117 A Engine Coolant Temperature
Sensor Low Input ECT sensor output voltage is below 0.08V. ECT sensor output voltage is
more than 0.08V. 1. Sensor signal circuit short to ground circuit.
2. ECT sensor malfunction.
3. ECM malfunction. A21 -
14
P0118 A Engine Coolant Temperature
Sensor High Input ECT sensor output voltage is more than 4.8V. The ECM uses default engine
coolant temperature value
based on start-up ECT and
time from start.
ECT sensor output voltage is
below 4.8V. 1. Sensor signal circuit open or short to voltage
circuit.
2. Sensor ground circuit open or short to voltage
circuit.
3. Poor connector connection
4. ECT sensor malfunction.
5. ECM malfunction. A21/
A22 P0406
1. No DTC relating to barometer sensor, ECT
sensor, CMP sensor, CKP sensor, MAF
sensor and TPS (low input & high input).
2. Engine speed is more than 2000rpm.
3. Engine coolant temperature is more than
75
C.
4. TPS output voltage is between 0.24V and
0.26V. Above conditions are met for 3
seconds.
OR
P0121 A Throttle Position Sensor
Range/Performance
1. No DTC relating to barometer sensor, ECT
sensor, CMP sensor, CKP sensor, MAF
sensor and TPS (low input & high input).
2. Engine speed is below 3200rpm.
3. Engine coolant temperature is more than
75
C.
4. TPS output voltage is between 4.54V and
4.56V. Above conditions are met for 3
seconds. No fail-safe function. TPS output voltage is below
0.24V or more than 0.26V.
OR
TPS output voltage is below
4.54V or more than 4.56V. 1. TPS malfunction.
2. Sensor signal circuit short to voltage circuit.
3. Electrical interference.
4. ECM malfunction. B27/
B26/
B39 - P0122 A Throttle Position Sensor Low
Input TPS output voltage is below 0.24V. TPS output voltage is more
than 0.24V. 1. Sensor power supply circuit open or short to
ground circuit.
2. Sensor signal circuit open or short to ground
circuit.
3. Poor connector connection.
4. TPS malfunction.
5. ECM malfunction. B27/
B26 P0336/
P0337
or
P0342
21
P0123 A Throttle Position Sensor High
Input TPS output voltage is more than 4.56V. The ECM uses default throttle
position value based on mass
air flow and engine speed.
TPS output voltage is below
4.56V. 1. Sensor power supply circuit short to voltage
circuit.
2. Sensor signal circuit short to voltage circuit.
3. Sensor ground circuit open or short to voltage
circuit.
4. Poor connector connection.
5. TPS malfunction.
6. ECM malfunction. B27/
B26/
B39 P0103/
P0113/
P0341/
P0342

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-143
An open or short to voltage circuit in the sensor ground circuit between the ECM terminal B39 and splice will cause
one or more of following DTCs to be set:





P0103 (Flash Code 61): Mass Air Flow Sensor Circuit High Input





P0113 (Flash Code 23): Intake Air Temperature Sensor High Input





P0123 (Flash Code 21): Throttle Position Sensor High Input





P0341(Flash Code 41): Camshaft Position Sensor Circuit Range/Performance





P0342 (Flash Code 41): Camshaft Position Sensor Circuit No Signal

An open circuit in the sensor power supply circuit between the ECM terminal B27 and splice will cause one or more of
following DTCs to be set:





P0122 (Flash Code 21): Throttle Position Sensor Low Input





P0342 (Flash Code 41): Camshaft Position Sensor Circuit No Signal

A short to ground circuit in the sensor power supply circuit between the ECM terminal B27 and splice will cause one
or more of following DTCs to be set:





P0122 (Flash Code 21): Throttle Position Sensor Low Input





P0336 (Flash Code 29): Crankshaft Position Sensor Circuit Range/Performance (58X)





P0337 (Flash Code 29): Crankshaft Position Sensor Circuit No Signal (58X)

A short to ground circuit in the sensor signal circuit between the ECM terminal B28 and sensor will cause one of
following DTC to be set:





P0337 (Flash Code 29): Crankshaft Position Sensor Circuit No Signal (58X)


RUW46EMF000101

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-145
DIAGNOSTIC TROUBLE CODE (DTC) P0101 (FLASH CODE 61) MASS AIR
FLOW SENSOR CIRCUIT RANGE/PERFORMANCE

RUW46EMF000101

Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
61 P0101 B Mass Air Flow Sensor
Circuit
Range/Performance
1. No DTC relating to barometer sensor, TPS, CMP sensor, CKP sensor and MAF sensor (low input & high input).
2. Engine speed is between 2800rpm and 4500rpm.
3. Throttle position sensor output voltage is between 1V and 3V.
4. Intake air temperature is between -14
C and 70
C.
5. Air flow amount below 0.04g/s (small air) or more than 177g/s (large air).
Above conditions are met for 3 seconds.
No fail-safe function.

6E-146 3.5L ENGINE DRIVEABILITY AND EMISSIONS
CIRCUIT DESCRIPTION
The mass air flow (MAF) sensor measures the amount
of air which passes through it into the engine during a
given time. The Engine Control Module (ECM) uses the
mass air flow information to monitor engine operating
conditions for fuel delivery calculations. A large quantity
of air entering the engine indicates an acceleration o
r
high load situation, while a small quantity or air indicates
deceleration or idle.
The MAF sensor produces a frequency signal which
can be monitored using a Tech 2. The frequency will
vary within a range of around 4 to 7 g/s at idle to around
25 to 40 g/s at maximum engine load. DTC P0101 will
be set if the signal from the MAF sensor does not match
a predicted value based on throttle position and engine
RPM.
DIAGNOSTIC AIDS
An intermittent may be caused by the following:
 Poor connections.
 Mis-routed harness.
 Rubbed through wire insulation.
 Broken wire inside the insulation.
Refer to Intermittents under service category
Symptoms.
Any un-metered air may cause this DTC to set. Check
for the following:
 The duct work at the MAF sensor for leaks.
 An engine vacuum leak.
 The PCV system for vacuum leaks.
 An incorrect PCV valve.
 The engine oil dip stick not fully seated.
 The engine oil fill cap loose or missing.


Diagnostic Trouble Code (DTC) P0101 (Flash Code 61)
Mass Air Flow Sensor Circuit Range/Performance
Step Action Value (s) Yes No
1
Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go to On Board
Diagnostic (OBD)
System Check
2
1. Connect the Tech 2.
2. Review and record the failure information.
3. Select "F0: Read DTC Infor By Priority" in "F0:
Diagnostic Trouble Code".
Is the DTC P0101 stored as "Present Failure"?
- Go to Step 3 Refer to
Diagnostic Aids
and Go to Step 3
3
1. Using the Tech2, ignition "On" and engine "Off".
2. Select "Clear DTC Information" with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the "F5: Failed
This Ignition" in "F2: DTC Information"
Was the DTC P0101 stored in this ignition cycle?
- Go to Step 4 Refer to
Diagnostic Aids
and Go to Step 4

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-147
Step Action Value (s) Yes No
4
1. Using the Tech 2, ignition "On" and engine "On".
2. Monitor the "Mass Air Flow" in the data display.
Does the Tech 2 indicate correct "Mass Air Flow" as
shown in the following graph, when engine speed is
increasing little by little?
Characteris tic of MAF Sens or -Ref erence (No Engine Load)-
0 5 10 15 20 25 30 35 40 45 50
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Eng i ne Speed ( r pm) ( T ech2 R eadi ng )
Mass Air Flow (g/s)
( T ec h2 R eadi ng)
- Go to Step 6 Go to Step 5
5
Remove the MAF & IAT sensor assembly and check
for the following conditions.

Objects blocking the air cleaner.

Objects blocking the MAF sensor.

Objects blocking the throttle valve.

Vacuum leaking at intake duct.

Vacuum leaking at throttle body.
If a problem is found, repair as necessary.
Was the problem found?
- Verify repair Go to Step 6
6
Check for poor/faulty connection at the MAF sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?


 E-61(B)
E-63






- Verify repair Go to Step 7
7
Remove the MAF & IAT sensor assembly and visually
check.
Was the problem found?
- Go to Step 11 Go to Step 8

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-149
DIAGNOSTIC TROUBLE CODE (DTC) P0102 (FLASH CODE 61) MASS AIR
FLOW SENSOR CIRCUIT LOW INPUT

RUW46EMF000101

Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
61 P0102 A Mass Air Flow Sensor
Circuit Low Input
MAF sensor output voltage is below 0.3V. The ECM uses default mass air flow
value based on IAC valve position,
throttle position, barometer pressure
and engine speed.