Mitsubishi Grandis. Manual — part 783
ON-VEHICLE SERVICE
MULTIPORT FUEL INJECTION (MPI)
13A-383
Examples of Abnormal Wave Patterns
•
Example 1
Cause of problem
Sensor interface malfunction. (Motor is not
operating)
Wave pattern characteristics
Induced electromotive force from the motor
turning dose not appear.
•
Example 2
Cause of problem
Open circuit in the line between the EGR valve
and the engine-ECU <M/T> or
engine-A/T-ECU <A/T>.
Wave pattern characteristics
Current is not supplied to the motor coil on the
open circuit side. (Voltage dose not drop to 0
V.)
Furthermore, the induced electromotive force
waveform at the normal side is slightly
different from the normal waveform.
ON-VEHICLE SERVICE
THROTTLE BODY (THROTTLE VALVE
AREA) CLEANING
M1131001000699
1. Remove the air intake hose from the throttle body.
2. Remove the throttle body assembly.
CAUTION
• Do not spray the cleaning fluid directly to the
throttle valve.
• Make sure the cleaning fluid does not enter
the motor from the bypass line. Also make
sure it does not enter the sensor through the
shaft.
3. Spray cleaning fluid on a clean cloth.
4. Wipe off the dirt around the throttle valve with the
cloth sprayed with cleaning fluid.
5. Install the throttle body assembly.
6. Attach the air intake hose.
FUEL PRESSURE TEST
M1131001900830
1. Release residual pressure from the fuel pipe line
to prevent fuel gush out (Refer to
CAUTION
Cover the hose connection with rags to prevent
splash of fuel that could be caused by some
residual pressure in the fuel pipe line.
2. Disconnect the high-pressure fuel hose at the
delivery pipe side.
AKX01608AE
AKX01609AF
Open
circuit
side
Normal
side
AK300686AC
ON-VEHICLE SERVICE
MULTIPORT FUEL INJECTION (MPI)
13A-384
3. Assemble the fuel pressure measurement tools
as follows.
<When using the fuel pressure gauge set (special
tool)>
a. Remove the union joint and bolt from the special
tool adaptor hose (MD998709) and attach the
special tool hose adaptor (MD998742) to the
adaptor hose.
b. Via a gasket, install the special tool fuel pressure
gauge set (MB991637 or MB991981) into the
special tool that has already assembled as
described in (a) above.
<When using the fuel pressure gauge>
a. Remove the union joint and bolt from special tool
adaptor hose (MD998709) and attach the special
tool hose adaptor (MD998742) to the adaptor
hose.
b. Via a suitable O-ring or gasket, install the fuel
pressure gauge to the special tool that has
already assembled as described in (a) above.
4. Install the assembled fuel pressure measurement
tools between the fuel rail and high-pressure fuel
hose.
CAUTION
To prevent damage to the MUT-III, always turn the
ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting the MUT-III.
5. Connect the MUT-III to the diagnosis connector.
6. Turn the ignition switch to ON position (But do not
start the engine).
7. Select "Item No. 07" from the MUT-III actuator test
to drive the fuel pump. Check that there are no
fuel leaks from any parts.
8. Finish the actuator test or turn the ignition switch
to "LOCK" (OFF) position.
9. Start the engine and run at idle.
10.Fuel pressure measurement while the engine is
running at idle.
Standard value: Approximately 248 kPa at
cerb idle
11.Disconnect the vacuum hose from the fuel
pressure regulator and measure fuel pressure
with the hose end closed by a finger.
Standard value: 324
− 334 kPa at cerb idle
12.Check to see that fuel pressure at idle does not
drop even after the engine has been raced
several times.
AKX01458 AG
MB 991637
Gasket
MD 998709
MD 998742
High-pressure
fuel hose
Delivery
pipe
AK305430AB
MB 991981
Gasket
MD 998709
MD 998742
High-pressure
fuel hose
Delivery
pipe
AKX01457AF
MD 998742
MD 998709
O-ring or gasket
Fuel pressure
gauge set
High-pressure
fuel hose
Delivery
pipe
AK300687
Vacuum hose
AC
ON-VEHICLE SERVICE
MULTIPORT FUEL INJECTION (MPI)
13A-385
13.Racing the engine repeatedly, hold the fuel return
hose lightly with 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 pressure in the return hose.
14.If any of fuel pressure measured in steps 10 to 13
is out of specification, troubleshoot and repair
according to the table below.
15.Stop the engine and check change of fuel
pressure gauge reading. 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.
16.Release residual pressure from the fuel pipe line
(Refer to
).
CAUTION
Cover the hose connection with rags to prevent
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 delivery pipe.
18.Replace the O-ring at the end of the fuel high
pressure hose with a new one. Furthermore,
apply engine oil to the new O-ring before
replacement.
19.Fit the fuel high pressure hose over the delivery
pipe and tighten the bolt to specified toque.
Tightening torque: 5
± 1 N⋅m
20.Check for any fuel leaks by following the
procedure in step 7.
21.Disconnect the MUT-III.
Symptom
Probable cause
Remedy
• Fuel pressure too low
• Fuel pressure drops after racing
• 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
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
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
ON-VEHICLE SERVICE
MULTIPORT FUEL INJECTION (MPI)
13A-386
FUEL PUMP RELAY DISCONNECTION
(HOW TO REDUCE PRESSURIZED FUEL
LINES)
M1131000900729
WARNING
When removing the fuel pipe, etc., release
fuel pressure to prevent fuel spray.
1. Remove the instrument panel fuse box lid <L.H.
drive vehicles> or instrument panel parcel box
<R.H. drive vehicles> (Refer to GROUP 52A
−
Instrument Panel
).
2. Remove the fuel pump relay (2) in the the junction
block.
3. Crank the engine for at least two seconds.
4. If the engine is not started, turn the ignition switch
to the "LOCK (OFF)" position.
5. If the engine is started, turn the ignition switch to
the "LOCK (OFF)" position after the engine
stopped.
6. Install the fuel pump relay (2).
7. Install the instrument panel fuse box lid <L.H.
drive vehicles> or instrument panel parcel box
<R.H. drive vehicles> (Refer to GROUP 52A
−
Instrument Panel
FUEL PUMP OPERATION CHECK
M1131002000829
1. Remove the fuel tank cap.
NOTE: As the fuel pump is an in-tank type, the
fuel pump sound is hard to hear. Then check the
sound from the tank inlet.
2. Check the operating of the fuel pump by MUT-III
to force-drive the fuel pump.
3. If the fuel pump will not operate, check by using
the following procedure. If normal, check the fuel
pump drive circuit.
(1) Turn the ignition switch to the "LOCK" (OFF)
position.
(2) Remove the second seat assembly, the rail
cover outer and the rail cover inner. (Refer to
GROUP 52A, Second Seat Assembly
Removal and Installation
).
AC310733AB
<L.H. drive vehicles>
Instrument panel fuse box lid
AC310315AB
<R.H. drive vehicles>
Instrument panel parcel box
AC310734
Fuel pump relay (2)
<L.H. drive vehicles>
AC302306 AD
Fuel pump relay (2)
<R.H. drive vehicles>
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