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 diagphragm according to the change of pressure inside of intake manifold.
DTC DESCRIPTION
PCM compares the difference between MAPS output and calculated MAPS value while enable condition ismet. If the acutal MAP value or lower than calculated(threshold) value for 2 minfailure during tip in-out driving,PCM determines that a fault exists and a DTC is stored.MIL(Malfunction Indicatin Lamp) turns on when the malfunction lasts till cosecutive 2 driving cycle.
DTC DETECTING CONDITION
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
●
Faulty TPS
●
Faulty MAPS
Enable
Conditions
●
Engine Coolant Temperature ≥ 60℃
(Fully Warmed up state)
●
600rpm < Engine Speed < 3000rpm
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 〈 Calculated MAP data
Diagnosis Time
●
Continuous
(For 2min. in mild tip in - out Driving)
MIL On Condition
●
2 Driving Cycles
SIGNAL WAVEFORM AND DATA
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.
SPECIFICATION
Pressure (kPa)
20
35
60
95
101.32
Voltage (V)
0.789
1.382
2.369
3.75
4
Tolerance (V)
± 0.045
SCHEMATIC DIAGRAM
MONITOR DTC STATUS
1.
Check DTC Status
(1)
Connect scantool to Data Link Connector(DLC).
(2)
IG "ON".
(3)
Select "Diagnostic Trouble Codes(DTCs)" mode, and then Press F4(DTAL) 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 codition then,go to " Component Inspection" procedure.
TERMINAL AND CONNECTOR INSPECTION
1.
Many malfunctions in the electrical system are caused by poor harness and terminals. 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 as necessary and go to "Verification of Vehicle Repair" procedure
▶ Go to " Power Circuit Inspection " procedure.
POWER CIRCUIT INSPECTION
1.
IG "OFF" and disconnect MAPS connector.
2.
IG "ON" ＆ ENG "OFF"
3.
Measure voltage between terminal 2 of MAPS harness connector and chassis ground.
Specification : Approx. 5V
4.
Is the measured voltage within specification ?
▶ Go to "Ground circuit inspection" procedure.
▶ Repair open or short to ground in harness and go to "Verification of Vehicle Repair" procedure.
GROUND CIRCUIT INSPECTION
1.
IG "OFF" and disconnect MAPS connector.
2.
Measure voltage between terminal 2 of MAPS harness connector and chassis ground.
3.
Measure voltage between terminal 2 and 4 of MAPS harness connector.
Specification : Voltage difference between Measurement "A" and "B" is below 200mV.
4.
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
1.
Check voltage
(1)
IG "OFF" and disconnect MAPS connector.
(2)
IG "ON" ＆ ENG "OFF"
(3)
Measure voltage between terminal 1 of MAPS harness connector and chassis ground.
Specification : Approx. 0V
(4)
Is the measured voltage within specification ?
▶ Go to "Check open in harness" as follows.
▶ Repair short to battery in harness and go to "Verification of Vehicle Repair" procedure.
2.
Check open in harness
(1)
IG "OFF" and disconnet MAPS and PCM connector.
(2)
Measure resistance between terminal 1 of MAPS harness connector and terminal 8 of PCM harness connector.
Specification : Approx. Below 1 Ω
(3)
Is the measured resistance within specification ?
▶ Go to "Component Inspection" procedure.
▶ Repair open in harness and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1.
Check TPS
(1)
Visually check that TPS is contaminated by foreign materials, deformed, or damaged
(2)
Has a problem been found ?
▶ Go to "Check MAPS Performance" as follows.
▶ 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.
2.
Check MAPS Performance
(1)
IG "OFF" and install scatool.
(2)
Connect probe to MAPS and TPS to check signal waveform by using oscilloscope function.
(3)
ENG "ON" and monitor signal waveform during accelleration and decelleration.
Specificaton :
Pressure (kPa)
20
35
60
95
101.32
Voltage (V)
0.789
1.382
2.369
3.75
4
Tolerance (V)
± 0.045
(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 scan tool and select "Diagnostic Trouble Codes(DTCs)" mode
2.
Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete". 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.
