The amount of intake air
flow must be inputted to PCM in order to determine the fuel injection
quantity. MAPS(Manifold Absolute Pressure) calculates the amount of air
indirectly as measuring the pressure inside of intake manifold. This
mechanism is also called Speed-Density Type.MAPS transfers analog output
signal which is proportional to the change of intake manifold pressure,
then, with this signal and RPM, PCM calculates the amount of intake air
flow. MAPS is mounted on surge tank to measure the pressure inside of
intake manifold, and it consists of a piezo electric element and hybrid IC
which amplifies output signal from the element. A piezo electric element
is a sort of a diaphragm using piezo electric effect. One side of the
diaphragm is surrounded with vacuum chamber while intake pressure is
applied to the other side. Thus, signals are outputted by the
transformation of diaphragm according to the change of pressure inside of
intake manifold.
PCM compares the
difference between MAPS output and calculated MAPS value while enable
condition is met. If the acutal MAP value or lower than
calculated(threshold) value for 2 min failure during
acceleration/deceleration, PCM determines that a fault exists and a DTC is
stored. MIL(Malfunction Indicator Lamp) turns on when the malfunction
lasts till consecutive 2 driving cycle.
Item
|
Detecting
Condition
|
Possible cause
|
DTC Strategy
|
| •
|
The MAP reading is compared to expected
MAP high and low limits based on engine speed & Throttle
Position | |
|
Enable
Conditions
|
Case
1
|
| •
|
Engine Coolant Temperature ≥ 60°C (Fully
Warmed up state) |
| •
|
600rpm < Engine Speed <
3000rpm | |
Case
2
|
- Power Test
| •
|
Altitude compensated MAP < Calculated
min. MAP data |
| •
|
Altitude compensated MAP > Calculated
max. MAP data | |
Threshold
value
|
Case
1
|
- Power Test
| •
|
Altitude compensated MAP < Calculated
min. MAP data |
| •
|
Altitude compensated MAP > Calculated
max. MAP data | |
Case
2
|
Deceleration Test
| •
|
Altitude compensated MAP < Memorized
MAP data | |
Diagnosis Time
|
| •
|
Continuous (For 2min. in mild tip in -
out Driving) | |
MIL On Condition
|
|
Pressure(kPa)
|
20
|
35
|
60
|
95
|
101.32
|
Voltage(V)
|
0.789
|
1.382
|
2.369
|
3.75
|
4
|
Tolerance(V)
|
± 0.045
|
It is necessary that
MAPS should be checked along with TPS. Because The MAP/TPS Rationality
Diagnostic is comprised of two tests. A deceleration test is performed to
provide a robust method for detection of an altitude compensated MAP value
that is too high for the deceleration condition. The second test compares
the altitude compensated MAP value to both high and low limits, dependent
upon throttle position and engine speed. When the MAP value is out of the
threshold range, the MAP/TPS system is determined to be
failed.
| 1. |
Check DTC Status
| (1) |
Connect scantool to Data Link
Connector(DLC). |
| (3) |
Select "DTC" button, and then Press "DTC
Status" to check DTC's information from the DTCs
menu. |
| (4) |
Read "DTC Status"
parameter.
|
| (5) |
Is parameter displayed "Present
fault"?
|
|
▶ Go
to "Component Inspection" procedure.
|
|
|
▶
Fault is intermittent caused by PCM memory was not
cleared after repair. Erase DTC and drive the vehicle to
satisfy the enable condition then, go to " Component
Inspection"
procedure.
|
| |
| 1. |
Check TPS
| (1) |
Visually check that TPS is contaminated
by foreign materials, deformed, or
damaged |
| (2) |
Has a problem been found ?
|
|
▶
Substitute with a known - good TPS and check for proper
operation.
If the problem is
corrected, replace TPS and go to "Verification of
Vehicle Repair" procedure.
|
|
|
▶ Go
to "Check MAPS Performance" as
follows.
|
| |
| 2. |
Check MAPS Performance
| (1) |
IG "OFF" and install
scantool. |
| (2) |
Connect probe to MAPS and TPS to check
signal waveform by using oscilloscope
function. |
| (3) |
ENG "ON" and monitor signal waveform
during acceleration and deceleration.
Specificaton :
Pressure(kPa)
|
Voltage(V)
|
Tolerance(V)
|
20
|
0.789
|
± 0.045
|
35
|
1.382
|
60
|
2.369
|
95
|
101.32
|
3.75
|
4
|
|
| (4) |
Is the measured signal waveform(MAP/TPS
Rationality) O.K ?
|
|
▶ Go
to "Verification of Vehicle Repair"
procedure.
|
|
|
▶
Substitute with a known - good MAPS and check for proper
operation. If the problem is corrected, replace MAPS and
go to "Verification of Vehicle Repair"
procedure.
|
| |
| Verification Of Vehicle
Repair |
After a repair, it is
essential to verify that the fault has been corrected.
| 1. |
Connect scantool and select "DTC"
button. |
| 2. |
Press "DTC Status" button and confirm that
"DTC Readiness Flag" indicates "Completed". If not, drive the
vehicle within conditions noted in the freeze frame data or enable
conditions |
| 3. |
Read "DTC Status"
parameter |
| 4. |
Is parameter displayed "History(Not Present)
fault"?
|
|
▶ System
performing to specification at this time. Clear the
DTC
|
|
|
▶ Go to the
applicable troubleshooting
procedure.
|
|
