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Isuzu Rodeo UE. Manual - part 418

6E2–427

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Detonation/Spark Knock Symptom

(Cont'd)

Step

Yes

Value(s)

Action

1. Check items that can cause an engine to run lean

(long term fuel trim significantly in the positive
range). For a lean condition, refer to

Diagnostic

Aids in DTC P0171 Diagnostic Support.

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

Was a problem found?

—

Verify repair

Go to

Step 10

1. Spark plugs for proper heat range. Refer to

General

Information.

2. If incorrect spark plugs are installed, replace spark

plugs as necessary.

Did any spark plugs require replacement?

—

Verify repair

Go to

Step 11

1. Remove excessive carbon buildup with a top engine

cleaner. Refer to instructions on the top engine
cleaner can.

2. Re-evaluate vehicle performance.

Is detonation still present?

—

Go to

Step 12

Verify repair

1. Check for an engine mechanical problem. Perform

a cylinder compression check. Refer to

Engine

Mechanical.

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

Was a problem found?

—

Verify repair

Go to

Step 13

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:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

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

6E2–428

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

Step

Action

Value(s)

Yes

DEFINITION:
Engine runs unevenly at idle. If severe, the engine or
vehicle may shake. Engine idle speed may vary in
RPM. Either condition may be severe enough to stall
the engine.

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to

Step 2

Go to

OBD

System

Check

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?

—

Go to

Step 13

Go to

Step 3

Was a visual/physical check performed?

—

Go to

Step 4

Go to

Visual/Physic

al Check

1. Check the PCM grounds for cleanliness, tightness

and proper routing. Refer to the PCM wiring
diagrams in

Electrical Diagnosis.

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

Was a problem found?

—

Verify repair

Go to

Step 5

Observe the long term fuel trim on the Tech 2.

Is the long term fuel trim significantly in the negative
range (rich condition)?

—

Go to

Step 6

Go to

Step 7

1. Check items that can cause the engine to run rich.

Refer to

Diagnostic Aids in DTC P0172 Diagnostic

Support.

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

Was a problem found?

—

Verify repair

Go to

Step 9

Is the long term fuel trim significantly in the positive
range (lean condition)?

—

Go to

Step 8

Go to

Step 9

1. Check items that can cause the engine to run lean.

Refer to

Diagnostic Aids in DTC P0171 Diagnostic

Support.

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

Was a problem found?

—

Verify repair

Go to

Step 9

1. Check for incorrect idle speed. Ensure that the

following conditions are present:

The engine is fully warm.

The accessories are “OFF.”

2. Using a Tech 2, monitor the IAC position.

Is the IAC position within the specified values?

Between 10

and 50

counts

Go to

Step 11

Go to

Step 10

6E2–429

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

(Cont'd)

Step

Yes

Value(s)

Action

1. Visually/physically inspect for the following

conditions:

Restricted air intake system. Check for a
possible collapsed air intake duct, restricted
air filter element, or foreign objects blocking
the air intake system.

Throttle body. Check for objects blocking the
IAC passage or throttle bore, excessive
deposits in the IAC passage and on the IAC
pintle, and excessive deposits in the throttle
bore and on the throttle plate.

Large vacuum leak. Check for a condition that
causes a large vacuum leak, such as an
incorrectly installed or faulty crankcase
ventilation valve or a disconnected brake
booster hose.

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

Was a problem found?

—

Verify repair

Go to

Step 8

Check the injector connections. If any of the injectors
are connected to an incorrect cylinder, correct as
necessary.

Was a problem found?

—

Verify repair

Go to

Step 12

1. Perform the “Injector Coil/Balance Test” in

Fuel

Metering System.

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

Was a problem found?

—

Verify repair

Go to

Step 13

1. Check for fuel in the pressure regulator vacuum

hose.

2. If fuel is present, replace the fuel pressure regulator

assembly. Refer to

Fuel Metering System.

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

Was a problem found?

—

Verify repair

Go to

Step 14

1. Check for proper ignition voltage output with spark

tester J 26792 (ST-125). Refer to

Electronic Ignition

System for the procedure.

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

Was a problem found?

—

Verify repair

Go to

Step 15

1. Remove spark plugs. Check for wet plugs, cracks,

wear, improper gap, burned electrodes, or heavy
deposits. Refer to

Electronic Ignition System.

NOTE: If spark plugs are gas or oil fouled, the cause of
the fouling must be determined before replacing the
spark plugs.

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

Was a problem found?

—

Verify repair

Go to

Step 16

1. Check for a loose ignition coil ground.

Refer to

Electrical Ignition System.

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

Was a problem found?

—

Verify repair

Go to

Step 17

6E2–430

RODEO 6VD1 3.2L ENGINE DRIVEABILITY AND EMISSIONS

Rough, Unstable, or Incorrect Idle, Stalling Symptom

(Cont'd)

Step

Yes

Value(s)

Action

1. Check ignition coils for cracks or carbon tracking.
2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

Go to

Step 18

Using a Tech 2, monitor the throttle position (TP) angle
with the engine idling.

Is the TP angle at the specified value and steady?

Go to

Step 19

Refer to

DTC

P0123 for

further

diagnosis

1. Check the positive crankcase ventilation (PCV)

valve for proper operation. Refer to

Crankcase

Ventilation System.

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

Was a problem found?

—

Verify repair

Go to

Step 20

1. Check the transmission range switch circuit. Use a

Tech 2 and be sure the Tech 2 indicates that the
vehicle is in drive with the gear selector in drive or
overdrive.

2. If a problem is found, diagnose and repair the

transmission range switch as necessary (refer to
4L30-E Automatic Transmission Diagnosis).

Was a problem found?

—

Verify repair

Go to

Step 21

1. Check for the following engine mechanical items.

Refer to

Engine Mechanical for diagnosis

procedures:

Low compression

Sticking or leaking valves

Worn camshaft lobe(s)

Camshaft drive belt slipped or stripped

Incorrect valve timing

Worn rocker arms

Broken valve springs

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

Was a problem found?

—

Verify repair

Go to

Step 22

1. Check for faulty motor mounts. Refer to

Engine

Mechanical for inspection of mounts.

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

Was a problem found?

—

Verify repair

Go to

Step 23

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:

Visual/physical inspection

Tech 2 data

Freeze Frame data/Failure Records buffer

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

Content .. 416 417 418 419 ..