Mitsubishi Lancer Evolution X. Manual - part 450

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-865

THROTTLE BODY (THROTTLE VALVE AREA) 
CLEANING

M1131001001625

WARNING

When touching the throttle valve, surely shut off the 
driving circuits of the throttle valve. In the event that 
the throttle valve is operated, a finger might be 
injured as the result of being caught by the throttle 
valve.

CAUTION

When the throttle body cleaning is performed, use scan 
tool MB991958 to initialize the learning value (Refer to 
GROUP 00, Precautions Before Service − Initialization Pro-

cedure for Learning Value in MFI Engine 

P.00-34

).

1. Disconnect the electronic-controlled throttle valve connector.
2. Remove the air intake hose from the throttle body.
3. Remove the throttle body.

CAUTION

Do not spray the cleaning solvent directly to the throttle 
valve.
4. Spray cleaning solvent on a clean cloth.

CAUTION

Make sure the cleaning solvent does not enter the motor 
and the sensor through the shaft.
5. Wipe off the dirt around the throttle valve with the cloth 

sprayed with cleaning solvent.

6. Install the throttle body.
7. Install the air intake hose.
8. Connect the electronic-controlled throttle valve connector.

FUEL PRESSURE TEST

M1131001902007

Required Special Tools:

• MB991958: Scan tool (M.U.T.-III Sub Assembly)

• MB991824: V.C.I.
• MB991827: USB Cable
• MB991910: Main Harness A

• MB991981: Fuel Pressure Gauge Set
• MB992001: Hose Adapter
• MB992049: Quick Connector
• MB992076: Injector Test Set

1. Release residual pressure from the fuel line to prevent fuel 

spray. (Refer to 

P.13A-868

.)

ON-VEHICLE SERVICE

TSB Revision

MULTIPORT FUEL INJECTION (MFI)

13A-866

WARNING

To prevent a fire, cover the hose connection with 
shop towels to prevent splashing of fuel that could be 
caused by some residual pressure in the fuel pipe 
line.

2. Disconnect the fuel high-pressure hose at the fuel rail side.

3. Assemble the special tool MB992076 (injector test set) as 

shown in figure according to the following procedure.

(1) Remove either the installation adapter for the injector or 

another adapter.

(2) Install the special tool MB992049 (quick connector) and 

the special tool MB992001 (hose adapter) to the hose 
without the adapter.

4. Install the special tool assembled in Step 3 between the fuel 

rail and the fuel high-pressure hose.

<When using the fuel pressure gauge>

a. Via a suitable O-ring or gasket, install the fuel pressure 

gauge to the special tool that has already assembled as 
described.

<When using the special tool MB991981 (fuel pressure 

gauge set)>

a. Via a gasket, install the special tool MB991981 (fuel pres-

sure gauge set) into the special tool that has already 
assembled as described.

b. Connect the leads from the fuel pressure gauge set to the 

power supply (cigarette lighter socket) and special tool 
MB991824 (V.C.I).

AK703186 AD

Radiator upper hose

AK604479AB

MB992076

MB992001

MB992049

AK604480 AE

O-ring or gasket

MB992076

Fuel rail

Fuel high
pressure hose

Fuel pressure gauge

AK604481AD

MB991981

Gasket

Fuel high
pressure hose

Fuel rail

MB992076

ON-VEHICLE SERVICE

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MULTIPORT FUEL INJECTION (MFI)

13A-867

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
5. Connect scan tool MB991958 to the data link connector.
6. Turn the ignition switch to the ON position (But do not start 

the engine).

7. Use Actuator test "item number 9" to drive the fuel pump. 

Check that there is no fuel leaking from any section when 
the fuel pump is operating.

8. Finish the actuator test or turn the ignition switch to the 

LOCK (OFF) position.

9. Start the engine and run at idle.
10.Measure fuel pressure while the engine is running at idle.

Standard value: Approximately 260 kPa (38 psi) at 
curb idle

11.Remove the vacuum hose from the intake manifold and 

measure fuel pressure after the nipple closed with a cap.

Standard value: 310 − 345 kPa (45 − 50 psi) at curb idle

12.Check to see that fuel pressure at idle does not drop even 

after the engine has been revved several times.

13.Revving the engine repeatedly, hold the fuel return hose 

lightly with your fingers to feel that fuel pressure is present in 
the return hose.
NOTE: If the fuel flow rate is low, there will be no fuel pres-
sure in the return hose.

14.If any of fuel pressure measured in Step 10 to 13 is out of 

specification, troubleshoot and repair according to the table 
below.

SYMPTOM

PROBABLE CAUSE

REMEDY

• Fuel pressure too low
• Fuel pressure drops after 

revving

• No fuel pressure in fuel return 

hose

Clogged fuel filter

Replace fuel filter

Fuel leaking to return side due to 
poor fuel regulator valve seating or 
settled spring

Replace fuel pressure regulator

Low fuel pump delivery pressure

Replace fuel pump

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

AK702618AD

Vacuum hose

Cap

ON-VEHICLE SERVICE

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MULTIPORT FUEL INJECTION (MFI)

13A-868

15.Stop the engine and observe fuel pressure gauge reading. It 

is normal if the reading does not drop within 2 minutes. If it 
does, observe the rate of drop and troubleshoot and repair 
according to the table below. Start, then stop the engine.

(1) Squeeze the fuel return line closed to confirm leak-down 

occurs from defective fuel pressure regulator.

(2) If pressure continues to drop with fuel return line 

squeezed closed, injector(s) or fuel pump are leaking.

16.Release residual pressure from the fuel pipe line. (Refer to 

P.13A-868

.)

WARNING

Cover the hose connection with shop towels to pre-
vent splash of fuel that could be caused by some 
residual pressure in the fuel pipe line.

17.Remove the fuel pressure gauge and special tool from the 

fuel rail.

18.Fit the fuel high-pressure hose to the fuel rail.
19.Check for fuel leaks.

(1) Use scan tool MB991958 to operate the fuel pump.
(2) Check the fuel line for leaks and repair as needed.

20.Disconnect scan tool MB991958.

HOW TO REDUCE PRESSURIZED FUEL 
PRESSURE

M1131000902509

When removing the fuel pipes and fuel hoses, follow the proce-
dure below to release fuel pressure in the line and prevent fuel 
from running out, because fuel pressure in the fuel line is high.
1. Remove the rear seat cushion assembly. (Refer to GROUP 

52A, Rear Seat Assembly 

P.52A-27

).

Fuel pressure too high

Binding valve in fuel pressure 
regulator

Replace fuel pressure regulator

Clogged fuel return hose or pipe

Clean or replace hose or pipe

Same fuel pressure when vacuum 
hose is connected and when 
disconnected

Damaged vacuum hose or 
clogged nipple

Replace vacuum hose or clean 
nipple

Defective fuel pressure regulator

Replace fuel pressure regulator

SYMPTOM

PROBABLE CAUSE

REMEDY

Fuel pressure drops gradually 
after engine is stopped

Leaky injector

Replace injector

Leaky fuel regulator valve seat

Replace fuel pressure regulator

Fuel pressure drops sharply 
immediately after engine is 
stopped

Check valve in fuel pump is held 
open

Replace fuel pump

SYMPTOM

PROBABLE CAUSE

REMEDY