DTC P0400 EXHAUST GAS RECIRCULATION FLOW
|
|
DTC P0400 EXHAUST GAS RECIRCULATION FLOW
|
Detect the malfunction of EGR system.
Intake manifold pressure (negative pressure)
is stable because the throttle valve is fully closed during the
fuel shut-off in deceleration. In this case, the intake manifold
pressure changes when EGR valve is opened or closed. Judge EGR system
is OK or NG according to intake manifold pressure change amount.
(1)
|
ECU
|
(4)
|
CPU
|
(7)
|
Battery
voltage
|
(2)
|
Detecting
circuit
|
(5)
|
EGR valve
|
|
|
(3)
|
Switching
circuit
|
(6)
|
Main relay
|
|
|
|
Secondary
Parameters
|
Enable
Conditions
|
After
engine starting
|
40
secs. or more
|
Engine
coolant temperature
|
≥ 70°C
(158°F)
|
Engine
speed
|
1200 ←→ 2950
rpm
|
Intake
manifold pressure (absolute pressure)
|
38.7
kPa (290 mmHg, 11.43 inHg)
|
Estimated
ambient temperature
|
≥ 5°C
(41°F)
|
Throttle
position
|
< 0.25°
|
Battery
voltage
|
> 10.9
V
|
Atmospheric
pressure
|
≥ 75.0
kPa (563 mmHg, 22.17 inHg)
|
Vehicle
speed
|
≥ 53
km/h (33 MPH)
|
Fuel
shut-off function
|
Operation
|
Neutral
switch
|
OFF
and 1 second after changing from “ON” to “OFF”
|
Load (air
conditioner, power steering, lights, rear defroster, heater fun
and radiator fan)
|
5 secs.
or more no change
|
Perform the diagnosis only once at the fuel
shut-off in deceleration in vehicle speed more than 53 km/h
(approx. 33 MPH). Pay attention to vehicle speed and engine speed.
(The diagnosis is not completed if vehicle speed and engine speed
are out of condition due to deceleration.)
Measure the pressure in the following procedures
when the enable conditions are completed, and then diagnosis by
calculating the result.
|
1.
|
PMOF1 is equal to the intake manifold pressure
at enable condition completed, and EGR target step is set to 50
steps (almost fully opened).
|
|
2.
|
PMON is equal to the intake manifold
pressure in 1 second after EGR target step is set 50 steps (when enable
conditions are completed), and EGR target step is set to 0 step.
|
|
3.
|
PMOF2 is equal to the intake manifold
pressure in 1 second after EGR target step is set to 0 step (in
2 seconds after enable conditions are completed).
|
Calculate the judged value using the following
formula.
Judged value = [PMON -
(PMOF1 + PMOF2)/2]
Judged value < 18.63 mmHg, 2.48
kPa (18.63 mmHg, 0.733 inHg) → NG
Judged value ≥ 2.48 kPa (18.63 mmHg,
0.733 inHg) → OK
Time Needed for Diagnosis:
Once
Malfunction Indicator
Light Illumination:
Illuminates when malfunction occurs in
2 continuous driving cycles.
(A)
|
Fuel shut-off
in deceleration
|
(E)
|
Intake manifold pressure (At normal condition)
|
(H)
|
Open
|
(B)
|
Diagnosis
enable condition
|
(I)
|
Close
|
(C)
|
EGR target
step
|
(F)
|
Diagnosis
mode timer
|
|
|
(D)
|
EGR actual
step
|
(G)
|
Diagnosis
starts.
|
|
|
|
•
|
When the OK idling cycle was completed 40 times
in a row
|
|
•
|
When “Clear Memory” was
performed
|
|
MALFUNCTION
INDICATOR LIGHT CLEAR CONDITION
|
|
•
|
When the OK driving cycle was completed 3 times
in a row
|
|
•
|
When “Clear Memory” was
performed
|
A/F main learning: Not allowed
Knock learning: Not allowed
EGR control: Not allowed to operate
|
ECM OPERATION
AT DTC SETTING
|
|
•
|
Memorize the freeze frame data. (For test mode $02)
|
|
•
|
Memorize the diagnosis value and trouble
standard value. (For test mode $06)
|
