Mitsubishi Lancer Evolution VI. Manual - part 35

MPI  – 

Troubleshooting

13-28

INSPECTION PROCEDURE 11

When the engine is cold, it stalls at idling. (Die out)

Probable cause

In such cases as the above, the cause is probably that the air/fuel mixture is inappropriate
when the engine is cold, or that the intake air volume is insufficient.

D

Malfunction of the ISC servo system

D

Malfunction of the throttle body

D

Malfunction of the injector system

D

Malfunction of the ignition system

Were the battery terminals disconnected recently?

Yes

After warming-up, let the engine run at idling for about 10 minutes.

No

MUT-

II

 Self-Diag code

Are diagnosis codes displayed?

Yes

Refer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.

OK

Check the fuel pressure. (Refer to P.13-30.)*

OK

Check the ignition timing. 
(Refer to GROUP 11 – Engine Adjustments.)*

NG

Check that the crank angle sensor and the timing belt cover are
installed properly.

OK

Check the following items.

D

Check the ignition coil, spark plugs, spark plug cables.

D

Check the compression pressure.

D

Check the engine oil viscosity.

OK

MUT-

II

 Data list

26 Idle position switch (Refer to P.13-58.)

NG

Check the idle position switch system.
(Refer to P.13-38, INSPECTION PROCEDURE 26.)

OK

Check the injector for operation sound.

NG

Check the injector system. (Refer to P.13-15, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)

Yes

Check the ISC servo for operation sound.

NG

Check the ISC servo system.
(Refer to P.13-44, INSPECTION PROCEDURE 33.)

No

Is engine-idling stable after the warming-up?

No

Check for unstable idling (Rough idling, hunting). 
(Refer to P.13-25, INSPECTION PROCEDURE 8.)

No

Does the engine stall right after the accelerator pedal is released?

Yes

Clean the throttle valve
area.

Adjust the fixed SAS. 
(Refer to P.13-30.)*

OK

MUT-

II

 Data list

21 Engine coolant temperature sensor (Refer to P.13-57.)

NG

Check the engine coolant temperature sensor system. 
(Refer to P.13-10, INSPECTION PROCEDURE FOR DIAGNOSIS
CODE 21.)

NOTE
*:

Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI  – 

Troubleshooting

13-29

INSPECTION PROCEDURE 12

When the engine is hot, it stalls at idling. (Die out)

Probable cause

In such cases as the above, the cause is probably that ignition system, air/fuel mixture,
idle speed control (ISC) or compression pressure is defective.
In addition, if the engine suddenly stalls, the cause may also be a defective connector
contact.

D

Malfunction of the ignition system

D

Malfunction of air-fuel ratio control system

D

Malfunction of the ISC servo system

D

Drawing air into intake system

D

Improper connector contact

D

Backflow of secondary air to the intake system

Were the battery terminals disconnected recently?

Yes

After warming-up, let the engine run at idling for about 10 minutes.

No

MUT-

II

 Diagnosis code

Are diagnosis codes displayed?

Yes

Refer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.

No

Check the ISC servo for operation sound.

NG

Check the ISC servo system.
(Refer to P.13-44, INSPECTION PROCEDURE 33.)

OK

Check the injector for operation sound.

NG

Check the injector system. (Refer to P.13-15, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)

OK

Does the engine stall right after the accelerator pedal is released?

Yes

Clean the throttle valve
area.

Adjust the fixed SAS. 
(Refer to P.13-30.)*

No

Does the engine stall easily again?

No

While carrying out an intermittent malfunction simulation test (Refer
to GROUP 00 – Points to Note for Intermittent Malfunctions.), check
for sudden changes in the signals shown below.

D

Crank angle sensor signal

D

Injector drive signal

D

Fuel pump drive signal

D

Air flow sensor signal

D

Secondary ignition signal

D

Engine-ECU power supply
voltage

Yes

MUT-

II

: Engine stalling inspection when the engine is warm and

idling. (Refer to P.13-50, INSPECTION PROCEDURE 42.)

OK

Check the ignition timing. 
(Refer to GROUP 11 – ENGINE ADJUSTMENTS.)*

NG

Check that the crank angle sensor and the timing belt cover are
installed properly.

OK

Check the following items.

D

Check the ignition coil, spark plugs, spark plug cables.

D

Check the secondary air supply system. (Ensure that there is no backflow of secondary air into the intake system.)

D

Check if the injectors are clogged.

D

Check the compression pressure.

D

Check if foreign materials (water, alcohol, etc.) got into fuel.

NOTE
*:

Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

MPI  – 

Troubleshooting

13-30

INSPECTION PROCEDURE 13

The engine stalls when starting the car. (Pass out)

Probable cause

In cases such as the above, the cause is probably misfiring due to a weak spark,
or an inappropriate air/fuel mixture when the accelerator pedal is depressed.

D

Drawing air into intake system

D

Malfunction of the ignition system

MUT-

II

 Self-Diag code

Are diagnosis codes displayed?

Yes

Refer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.

No

Check the following items.

D

Check the ignition coil, spark plugs, spark plug cables.

D

Check if air was drawn into the intake system.

Broken intake manifold gasket
Broken or disconnected vacuum hose
Improper operation of the PCV valve
Broken air intake hose

INSPECTION PROCEDURE 14

The engine stalls when decelerating.

Probable cause

In cases such as the above, the cause is probably that the intake air volume is insufficient
due to a defective idle speed control (ISC) servo system.

D

Malfunction of the ISC servo system

No

MUT-

II

 Data list

26 Idle position switch (Refer to P.13-XX.)

NG

Check the idle position switch system.
(Refer to P.13-XX, INSPECTION PROCEDURE 26.)

OK

MUT-

II

 Data list

14 Throttle position sensor (Refer to P.13-57.)

NG

Check the throttle position sensor system. (Refer to P.13-9, IN-
SPECTION PROCEDURE FOR DIAGNOSIS CODE 14.)

OK

MUT-

II

 Data list

45 ISC servo position

D

Is the idle speed control (ISC) servo position drops to 0 – 2
steps when decelerating (engine r/min less than 1,000)?

Yes

Check the vehicle speed sensor system. (Refer to P.13-13, INSPEC-
TION PROCEDURE FOR DIAGNOSIS CODE 24.)

No

Check the following items.

D

Check the ignition coil, spark plugs, spark plug cables.

D

Clean the throttle valve area.

D

Check and adjust the fixed SAS.

No

MUT-

II

 Data list

26 Idle position switch (Refer to P.13-58.)

NG

Check the idle position switch system.
(Refer to P.13-38, INSPECTION PROCEDURE 26.)

No

MUT-

II

 Self-Diag code

Are diagnosis codes displayed?

Yes

Refer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.

Were the battery terminals disconnected recently?

Yes

After warming-up, let the engine run at idling for about 10 minutes.

MPI  – 

Troubleshooting

13-31

INSPECTION PROCEDURE 15

Hesitation, sag or stumble

Probable cause

In cases such as the above, the cause is probably that ignition system, air/fuel mixture
or compression pressure is defective.

D

Malfunction of the ignition system

D

Malfunction of air-fuel ratio control system

D

Malfunction of the fuel supply system

D

Poor compression

D

Malfunction of the turbocharger system

D

Malfunction of the secondary air supply system

MUT-

II

 Self-Diag code

Are diagnosis codes displayed?

Yes

Refer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.

No

Check the injectors for operation sound.

NG

Check the injector system. (Refer to P.13-15, INSPECTION PRO-
CEDURE FOR DIAGNOSIS CODE 41.)

OK

Check the ignition timing. 
(Refer to GROUP 11 – Engine Adjustments.)*

NG

Check that the crank angle sensor and the timing belt cover are
installed properly.

OK

MUT-

II

: Check if hesitation, sag, stumble or poor acceleration

occurs. (Refer to P.13-51, INSPECTION PROCEDURE 43.)

OK

Check the fuel pressure. (Refer to P.13-30.)*

OK

Check the following items.

D

Check the ignition coil, spark plugs, spark plug cables.

D

Check the turbocharger boost pressure.

D

Check the boost pressure control system.

D

Check the turbocharger turbine wheel for smooth rotation.

D

Check the compression pressure.

D

Check the fuel filter or fuel line for clogging.

D

Check the secondary air supply system.

NOTE
*:

Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).

INSPECTION PROCEDURE 16

The feeling of impact or vibration when accelerating

Probable cause

In cases such as the above, the cause is probably that there is an ignition leak
accompanying the increase in the spark plug demand voltage during acceleration.

D

Malfunction of the ignition system

MUT-

II

 Self-Diag code

Are diagnosis codes displayed?

Yes

Refer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.

No

Check the following items.

D

Check the ignition coil, spark plugs, spark plug cables.

D

Check for occurrence of ignition leak.