MULTIPORT FUEL INJECTION (MFI) DIAGNOSIS
TSB Revision
MULTIPORT FUEL INJECTION (MFI) <3.0L>
13B-337
•
Intake air temperature is higher than 0
°
C (32
°
F).
•
Barometric pressure is higher than 76 kPa (11
psi).
•
Vehicle speed is 1.5 km/h (0.9 mph) <M/T> or 30
km/h (18.7 mph) <A/T> or more.
•
At least 90 seconds have passed since manifold
differential pressure sensor output voltage fluctu-
ated 1.5 volts or more.
•
The throttle valve is closed.
•
Volumetric efficiency is lower than 18 <M/T> or
28 <A/T> percent.
•
While fuel is being shut off. <M/T>
•
The ECM <M/T> or PCM <A/T> monitors for this
condition for 3 cycles of 2 seconds each during
the drive cycle.
Judgement Criteria
•
When intake manifold pressure fluctuations width
is lower than 2.6 kPa (0.38 psi). When the EGR
solenoid is turned ON.
.
TROUBLESHOOTING HINTS (The most likely
causes for this code to be set are: )
•
EGR valve does not open.
•
EGR control vacuum is too low.
•
EGR solenoid failed.
•
Open or shorted EGR solenoid circuit, or loose
connector.
•
Manifold differential pressure sensor failed.
•
ECM failed. <M/T>
•
PCM failed. <A/T>
DIAGNOSIS
Required Special Tool:
•
MB991502: Scan Tool (MUT-II)
STEP 1. Check the EGR system.
Refer to GROUP 17, Emission Control System
−
Exhaust Gas
Recirculation (EGR) System
−
EGR System Check
.
Q: Are there any abnormalities?
YES :
Go to Step 2.
NO :
Repair it. Then go to Step 3.
STEP 2. Using scan tool MB991502, check data list item 95:
Manifold Differential Pressure Sensor.
CAUTION
To prevent damage to scan tool MB991502, always turn the
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Start the engine and run at idle.
(3) Set scan tool MB991502 to the data reading mode for item
95, Manifold Differential Pressure Sensor.
(4) Warm up the engine to normal operating temperature: 80
°
C
to 96
°
C (176
°
F to 205
°
F).
•
Should be between 62
−
76 kPa at engine idling.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES :
Clean the EGR valve and EGR passage. Then go to
Step 3.
NO :
Refer to, DTC P1400
−
Manifold Differential Pressure
Sensor Circuit Malfunction
.
AKX01177
16 PIN
MB991502
AB