Isuzu Rodeo UE. Manual - part 251

6E1–375

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

HESITATION, SAG, STUMBLE SYMPTOM

DEFINITION:
Momentary lack of response as the accelerator is pushed
down. Can occur at any vehicle speed. Usually most
pronounced when first trying to make the vehicle move,
as from a stop sign. May cause the engine to stall if severe
enough.

Step

Action

Value(s)

Yes

No

1

Was the On–Board Diagnostic (OBD) System Check
performed?

—

Go to Step 2 

Go to OBD

System

Check 

2

1. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,

correct the condition as instructed in the bulletin.

Was a bulletin found that addresses the symptom?

—

Verify repair

Go to Step 3 

3

Was a visual/physical check performed?

—

Go to Step 4 

Go to Visual /

Physical

Check 

4

1. Check the fuel control heated oxygen sensor

(HO2S1). The HO2S1 should respond quickly to
different to throttle positions. If it doesn’t, check for
silicon or other contaminants from fuel or use of
improper RTV sealant. The sensors may have a
white powdery coating. Silicon contamination
sends a rich exhaust signal which causes the PCM
to command an excessively lean air/fuel mixture.

Was a problem found?

—

Verify repair

Go to Step 5 

5

Check the fuel pressure. Refer to Fuel System
Pressure Test.

Was a problem found?

—

Verify repair

Go to Step 6 

6

Observe the ”TP angle” display on the Tech 2 while
slowly increasing throttle pedal.

Does the TP angle display steadily increase from 0% at
closed throttle to 100% at WOT?

—

Go to Step 7 

Go to Step 13

7

Monitor ”Long Term Fuel Trim” on the Tech 2.

Is the ”Long Term Fuel Trim” in the negative range (rich
condition)?

—

Go to Step 8 

Go to Step 9 

8

Check items that can cause the engine to run rich.
Refer to Diagnostic Aids in DTC P0172.

Was a problem found?

—

Verify repair

Go to Step 10

9

Check items that can cause the engine to run lean.
Refer to Diagnostic Aids in DTC P0171.

Was a problem found?

—

Verify repair

Go to Step 10

10

Check for proper ignition voltage output with spark
tester J 26792 (ST–125). For the procedure, refer to
Electronic Ignition System.

Was a problem found?

—

Verify repair

Go to Step 11

11

Check for a loose ignition control module ground.

Was a problem found?

—

Verify repair

Go to Step 12

6E1–376

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

Step

No

Yes

Value(s)

Action

12

Visually/physically inspect the secondary ignition
wires. Check for the following conditions:

f

Verify that all ignition wire resistances are less
than the specified value.

f

Value that ignition wires are correctly routed to
eliminate cross–firing.

f

Verify that ignition wires are not arcing to ground.
Spraying the secondary ignition wires with a light
mist of water may help locate an intermittent
problem.

Was a problem found?

30,000 

W

Verify repair

Go to Step 14

13

Replace the TP sensor.

—

Verify repair

—

14

1. Check the ignition coil secondary resistance.
2. Replace the coil if it is not within the specified value.

Was a problem found?

9 k

W

– 12k

W

Verify repair

Go to Step 15

15

1. Remove the spark plugs and check for gas or oil

fouling, cracks, wear, improper gap, burned
electrodes of heavy deposits.

2. If spark plugs are fouled, the cause of fouling must

be determined before replacing the spark plugs.

Was a problem found?

—

Verify repair

Go to Step 16

16

Check the PCM grounds to verify that they are clean
and tight. Refer to the PCM wiring diagrams in
Electrical Diagnosis.

Was a problem found?

—

Verify repair

Go to Step 17

17

Visually/physically check vacuum hoses for splits,
kinks, and proper connections and routing as shown on
the Vehicle Emission Control Information label.

Was a problem found?

—

Verify repair

Go to Step 18

18

1. Review all diagnostic procedures within this table.
2. If all procedures have been completed and no

malfunctions have been found, review/inspect the
following:

f

Visual/physical inspection

f

Tech 2 data

f

Freeze Frame data/Failure Records buffer

f

All electrical connections within a suspected
circuit and/or system

3. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Contact

Technical

Assistance

6E1–377

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

RESTRICTED EXHAUST SYSTEM CHECK

Step

Action

Value(s)

Yes

No

1

Was the On–Board Diagnostic (OBD) System Check
performed?

—

Go to Step 2 

Go to OBD

System

Check 

2

1. Remove the HO2S2.

f

For removal procedures, refer to Heated
Oxygen Sensors in On–Vehicle Service. 

2. Install the Exhaust Backpressure Tester in place of

the Bank 1 HO2S.

3. Idle the engine at normal operating temperature.

Does the reading on the gauge exceed the specified
value?

8.62 kPa

(1.25 psi)

Go to Step 5 

Go to Step 3 

3

With the exhaust back–pressure tester in place of
HO2S, and the engine at normal operating
temperature:
Increase the engine speed to 2000 RPM while
observing the gauge.

Does the reading exceed the amount of the value
column?

8.62 kPa

(1.25 psi)

Go to Step 5 

Go to Step 4 

4

1. Re–install the HO2S2. (Refer to Heated Oxygen

Sensors in On–Vehicle Service for installation
procedure.) 

2. Remove the HO2S1.
3. Install the Exhaust Back–Pressure Tester BT8515V

or equivalent in place of the HO2S1.

4. Bring the engine to normal operating temperature

while observing the gauge.

5. Increase the engine speed to 2000 RPM (allow 10

seconds for pressure build) and observe the gauge.

Did the reading exceed the specified value?

8.62 kPa

(1.25 psi)

Go to Step 6 

System OK

5

Repair a restiction in the exhaust system after the
catalytic converter.
Possible faults include:

f

Collapsed pipe

f

Internal muffler failure

—

Verify repair

—

6

Replace the restricted catalytic converter.

—

Verify repair

—

NOTE: Diagnostic Trouble Codes will be set by running
the vehicle to normal operating temperature after a cold
start with the O2 sensor disconnected. After performing
these tests, use the Tech 2 to erase the Diagnostic
Trouble Codes that were set by the lack of O2 sensor
activity.

6E1–378

RODEO X22SE 2.2L ENGINE DRIVEABILITY AND EMISSION

DEFAULT MATRIX TABLE

SERVICE PROCEDURE DEFAULT
STRATEGY

A referral strategy has been established to assist the
technician with additional information when the cause of
the failure cannot be determined. If no problem is found
after performing diagnostics, then for further diagnostic
information, refer to the default matrix table.

DEFAULT MATRIX TABLE

Strategy Based Diagnostic Charts

Initial Diagnosis

Default Section(s)

On–Board Diagnostic (OBD) System
Check

Vehicle does not enter diagnostics.

Chassis Electrical

On–Board Diagnostic (OBD) System
Check

Vehicle enters diagnostics and
communicates with the Tech 2. MIL is
ON in diagnostics. Engine does not
start and run.

Ignition System Check

On–Board Diagnostic (OBD) System
Check

Engine starts and runs, no PCM codes
set. Customer complains of vibration.

—

PCM Power and Ground Check

On–Board Diagnostic (OBD) System
Check.

Chassis Electrical

PCM Power and Ground Check

On–Board Diagnostic (OBD) System
Check. PCM power and ground circuits
OK. Data link voltage incorrect.

Chassis Electrical

Symptoms

Initial Diagnosis

Default Section(s)

Intermittents

1. On–board diagnostic (OBD)

system check.

2. Careful visual/physical inspections.

Chassis Electrical

Hard Starts

1. OBD system check.
2. Sensors (ECT, MAP, TP); MAP

output chart.

3. Fuel system electrical test, fuel

system diagnosis.

4. Ignition system.
5. IAC system check.

Engine Mechanical

Ignition System Check
Exhaust System Diagnosis

Surges and/or Chuggles

1. OBD system check.
2. Heated oxygen sensors.
3. Fuel system diagnosis.
4. Ignition system.

Calibration ID ”Broadcast
Code”/Service Bulletins

Ignition System Check
Generator Output
Exhaust System Diagnosis

Lack of Power, Sluggish or Spongy

1. OBD system check.
2. Fuel system diagnosis.
3. Ignition system.
4. EGR operation.
5. EGR system check.

Refer to Exhaust System in
Engine Exhaust

TCC Operation
Calibration ID/Service Bulletins

Detonation / Spark Knock

1. OBD system check.
2. EGR operation.
3. EGR system check.
4. Fuel system diagnosis.
5. Ignition system.

Cooling System

Ignition System Check
Calibration ID/Service Bulletins