3. Schematic:

Ignition System

 MAIN

87

86

30

85

B

A

C

EF22

EF01

IF30

EO01

EO01

1

17

COILA

COILB

Main Relay

From Battery

Engine 

Control 

Module

Ignition Switch

Ignition Coil A

Ignition Coil B

FE02-5271b

Engine

Control System JL4G15-D

2-715

Fuel Injector

MAIN

EF12

5

2

3

1

63

64

MPR

EO35

62

EO01

EO01

EO01

EO01

65

66

INJD

INJB

INJC

INJA

Main Relay

From Battery

Engine 

Control 

Module

Cylinder No.1 Fuel Injector

Cylinder No.4 Fuel Injector

Cylinder No.2 Fuel Injector

Cylinder No.3 Fuel Injector

FE02-5272b

4. Diagnostic Steps:

Note

–

If the control system stores DTC other than misfire, diagnose these DTC first and eliminate the faults.

–

If the vehicle does not have a misfire when sent to a service station, road test the vehicle, so that the misfire will
occur again. Use scan tool to record ECM data when misfire is occurring, in order to facilitate analyzing the cause
of the fault.

–

If after a long period road test, ECM does not store any misfire associated DTC codes, then the fault may be due
to the following reasons:

•

Overfill fuel tank and fuel enters into the evaporative emission control system, so that the mixture is too rich and
causes misfire.

•

Use improper fuel caused poor combustion and misfire.

•

Contaminated spark plug causes the ignition failure and misfire.

•

Carry out basic checks at fault locations identified by DTC codes.

–

Road test the vehicle after repair to confirm no DTC is stored.

Step 1

Initial Inspection

(a)

Check the wiring harness connector for damage, poor
connection, aging or signs of loosening.

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Control System JL4G15-D

Engine

(b)

Check the vacuum tube for damaged, loose, leakage and so
on.

Next

Step 2

Check for other DTC codes.

(a)

Connect scan tool to the datalink connector.

(b)

Turn the ignition switch to "ON" position.

(c)

Press the scan tool power button.

(d)

Select the following menu items: Engine/Read DTC codes.

(e)

Read DTC codes.

Results:

DTC Codes Shown

To Step

DTC Codes Other Than DTC P0300-P0304

No

DTC P0300

Yes

No

Refer to 

2.12.7.14

 

DTC Code Index

.

Yes

Step 3

Check valves and air intake system.

(a)

Check vacuum solenoid valve Canister connection is correct
or not and leakage.

(b)

Check the vacuum brake booster vacuum tube connection is
correct or not and leakage.

(c)

Check the intake tube pressure sensor connection is correct
or not and leakage.

(d)

Check purged crankcase ventilation valve, ventilation pipe
connection is correct or not and leakage.

(e)

Check whether there is intake leakage.

Is there above mentioned fault?

Yes

Repair the faulty part. Go to step 17

No

Step 4

Check the spark plug.

(a)

Remove the spark plug from the misfire cylinder.

(b)

Check whether the spark plug gap is too large or too small.

Standard Gap: 0.8-1.0 mm (0.031-0.039 in)

(c)

Check the existence of spark plug electrode erosion,
damage.

(d)

Check whether the spark plug and the electrode part skirt is
wet or not and check the existence of a serious gasoline
leakage.

(e)

Reinstall the spark plug.

Is there above mentioned fault?

Engine

Control System JL4G15-D

2-717

Yes

Replace the spark plug. Refer to

2.10.8.4

 

Spark Plug Replacement

. Go to step

8

No

Note

Prior to the implementation of this program, the following conditions must be met:
1. Disconnect all fuel injector connectors.

2. Engine running time must not be longer than 5 s.

Step 5

Check whether the spark plug arcing is normal.

(a)

Test the spark.

(b)

Remove misfire cylinder ignition wires.

(c)

Disconnect all fuel injector cylinder connectors.

(d)

Install the ignition wires to the spark plug.

(e)

Run the engine (the engine running time no longer than 5s)
and check the arcing.

(f)

Reconnect all cylinder fuel injector connectors.

(g)

Install the ignition wires.

Is spark plug arcing normal?

No

Go to step 9

Yes

Step 6

Check the misfire cylinder compression pressure.

(a)

For detailed steps. Refer to .

Is cylinder compression pressure normal?

Yes

Go to step 10

No

Step 7

Check the cause of cylinder compression pressure too low. Refer to the "Engine Mechanical System" in
the

2.6.7

 

Diagnostic Information and Procedures

.

Step 8

Check fuel and misfire cylinder fuel injectors.

(a)

Check whether there is fuel injectors leakage and stagnate.

(b)

Check fuel quality.

Is there above mentioned fault?

Yes

Repair the faulty part. Go to step 17

No

Note

Prior to the implementation of this test, the following conditions must be met:
1. Disconnect all fuel injector connectors.

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Control System JL4G15-D

Engine