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.
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