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.
Checking output signals
of MAPS under detecting condition, if an output signal is intermittently
above 4.5V ., PCM sets P1106.
Item
|
Detecting
Condition
|
Possible Cause
|
DTC Strategy
|
| •
|
Monitor the signal of MAP
sensor | |
| •
|
Short to battery in signal
circuit |
|
Enable Conditions
|
Case
1
|
| •
|
No TPS Active Fault
Present |
| •
|
Engine Running Time >
10sec. |
| •
|
Throttle Position ≤
30% | |
Case
2
|
| •
|
No TPS Active Fault
Present |
| •
|
Engine Running Time >
10sec. |
| •
|
Throttle Position ≤
40% | |
Threshold value
|
| •
|
Intermittently MAP Signal >
4.5V | |
Diagnosis Time
|
|
MIL On Condition
|
|
Pressure(kPa)
|
20
|
35
|
60
|
95
|
101.32
|
Voltage(V)
|
0.789
|
1.382
|
2.369
|
3.75
|
4
|
Allowable
error(V)
|
± 0.045
|
Comparing MAPS and TPS,
The signals of MAPS and TPS increasess and decrease
simultaneously.
| 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 "Terminal and connector inspection"
procedure.
|
|
|
▶
Fault is intermittent caused by poor contact in the
sensor's and/or PCM's connector or was repaired and PCM
memory was not cleared. Thoroughly check connectors for
looseness, poor connection, ending, corrosion,
contamination, deterioration, or damage. Repair or
replace as necessary and go to "Verification of Vehicle
Repair"
procedure.
|
| |
| Terminal And Connector
Inspection |
| 1. |
Many malfunctions in the electrical system are
caused by poor harness and terminal condition. Faults can also be
caused by interference from other electrical systems, and mechanical
or chemical damage. |
| 2. |
Thoroughly check connectors for looseness,
poor connection, bending, corrosion, contamination, deterioration,
or damage. |
| 3. |
Has a problem been found ?
|
|
▶ Repair or
replace if necessary and go to "Verification of Vehicle
Repair" procedure
|
|
|
▶ Go to
"Power Circuit Inspection"
procedure.
|
|
■ Check voltage
| 2. |
Disconnect MAPS
connector. |
| 4. |
Measure the voltage between power terminal of
MAPS harness connector and ground.
Specification
: Approx. 5V
| |
| 5. |
Is the measured voltage within specification
?
|
|
▶ Go to
"Ground Circuit Inspection" procedure.
|
|
|
▶ If the
voltage is over 5.1V, check short to battery in
harness.
▶ Repair or replace as
necessary and then, go to "Verification of Vehicle Repair"
procedure.
|
|
| Ground Circuit
Inspection |
■ Check open in harness
| 2. |
Disconnect MAPS
connector. |
| 4. |
Measure the voltage between power terminal of
MAPS harness connector and chassis ground. (Measurement
"A") |
| 5. |
Measure the voltage between power and ground
terminals of MAPS harness connector. (Measurement "B")
Specification
: "A" - "B" = : Approx. below
200mV
| |
| 6. |
Is the measured voltage within specification
?
|
|
▶ Go to
"Signal Circuit Inspection" procedure.
|
|
|
▶ Repair
contact reistance or open in harness and then go to
"Verification of Vehicle Repair"
procedure.
|
|
| Signal Circuit
Inspection |
■ Check short to battery in harness
| 2. |
Disconnect MAPS and PCM
connector. |
| 3. |
Measure resistance between signal and power
terminals of MAPS harness connector.
|
| 4. |
Is the measured resistance within
specification ?
|
|
▶ Go to
"Component Inspection" procedure.
|
|
|
▶ Repair
contact resistance or open in harness and then go to
"Verification of Vehicle Repair"
procedure.
|
|
| 1. |
MAPS performance test
| (2) |
Connect scantool to Data Link
Connector(DLC) and select "Oscilloscope" then, connect probes
to output signal lines of MAPS and TPS.Turn engine "ON" and
monitor the waveforms accelerating or
decelerating |
| (3) |
Start engine 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
|
3.75
|
101.32
|
4
|
|
| (4) |
Is the waveform displayed
correctly?(Compare the response time of TPS and
MAPS)
|
|
▶
Substitute with a known - good PCM and check for proper
operation. If the problem is corrected, replace PCM and
go to "Verification of Vehicle Repair"
procedure.
|
|
|
▶
After replacing MAPS with new one, if it operates
normally, replace MAPS and go to "Verification of
Vehicle
Repair".
|
| |
| 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.
|
|
