MPI – Troubleshooting13-31
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.Malfunction of the ignition system
Malfunction of air-fuel ratio control system
Malfunction of the fuel supply system
Poor compression
Malfunction of the turbocharger system
Malfunction of the secondary air supply system
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
No
Check the injectors for operation sound.NGCheck 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.)*NGCheck 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.
Check the ignition coil, spark plugs, spark plug cables.
Check the turbocharger boost pressure.
Check the boost pressure control system.
Check the turbocharger turbine wheel for smooth rotation.
Check the compression pressure.
Check the fuel filter or fuel line for clogging.
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.Malfunction of the ignition system
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
No
Check the following items.
Check the ignition coil, spark plugs, spark plug cables.
Check for occurrence of ignition leak.
MPI – Troubleshooting13-32
INSPECTION PROCEDURE 17
The feeling of impact or vibration when decelerating
Probable cause
Malfunction of the ISC servo system is suspected.Malfunction of the ISC servo system
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
No
Check the ISC servo for operation sound.NGCheck the ISC servo system.
(Refer to P.13-44, INSPECTION PROCEDURE 33.)
OK
MUT-II Data list
14 Throttle position sensor (Refer to P.13-57.)NGCheck the throttle position sensor system. (Refer to P.13-9, IN-
SPECTION PROCEDURE FOR DIAGNOSIS CODE 14.)
OK
MUT-II Data list
26 Idle position switch (Refer to P.13-58.)NGCheck the idle position switch system.
(Refer to P.13-38, INSPECTION PROCEDURE 26.)
OK
Clean the throttle valve area.
INSPECTION PROCEDURE 18
Poor acceleration
Probable cause
Defective ignition system, abnormal air-fuel ratio, poor compression pressure, etc.
are suspected.Malfunction of the ignition system
Malfunction of air-fuel ratio control system
Malfunction of the fuel supply system
Poor compression pressure
Clogged exhaust system
Malfunction of the turbocharger system
MUT-II Self-Diag code
Are diagnosis codes displayed?Ye sRefer to P.13-8, INSPECTION CHART FOR DIAGNOSIS CODES.
No
Check the injectors for operation sound.NGCheck 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.)*NGCheck that the crank angle sensor and the timing belt cover are
installed properly.
OK
MUT-II: Check if hesitation, sag, stumble or poor acceleration occur.
(Refer to P.13-51, INSPECTION PROCEDURE 43.)
OK
Check the fuel pressure. (Refer to P.13-30.)*
OK
Check the following items.
Check the ignition coil, spark plugs, spark plug cables.
Check the turbocharger boost pressure.
Check the boost pressure control system.
Check the turbocharger turbine wheel for smooth rotation.
Check the compression pressure.
Check the fuel filter or fuel line for clogging.
Broken air intake hose
Clogged air cleaner
Clogged exhaust system
NOTE
*: Refer to Workshop Manual for LANCER EVOLUTION-IV and EVOLUTION-V (Pub. No. S9806CNCP9).
