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.
PCM compares the MAPS output and calculated MAPS value while enable condition ismet. If the acutal MAP value is higher than Maximum threshold or lower than Minimum threshold for 15 secondfailure during one diagnostic test(32 second),PCM determines that a fault exists and a DTC is stored.MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till cosecutive 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 | ● Poor connection ● Open or short in harness ● MAPS ● PCM |
Enable Conditions | Case 1 | Power conditions ● Engine running ● Disabling faults present ● Power stable conditions present ● 1300rpm ≤ Engine speed ≤ 4000rpm ● The minimum consecutive time > 1.5s |
Case 2 | Deceleration conditions ● Engine running ● Disabling faults present ● Transimssion torque converter clutch condition stable ● Decel stable conditions present ● 1200rpm ≤ Engine speed ≤ 4500rpm ● Throttle position < 7.9% ● Vehicle speed ≥ 30kph ● The minimum consecutive time > 1.5s | |
Threshold Value | Case 1 | ● Power Test ● Altitude compensated MAP < Memorized min. MAP data ● Altitude compensated MAP > Memorized max. MAP data |
Case 2 | ● Deceleration Test ● Altitude compensated MAP < Memorized MAP data | |
Diagnosis Time | ● Continuous (More than 15 seconds failure for every 32 seconds test ) | |
MIL On Condition | ● 2 Driving Cycles |
Pressure (kPa) | 20 | 35 | 60 | 95 | 101.32 |
Voltage (V) | 0.789 | 1.382 | 2.369 | 3.75 | 4 |
Tolerance (V) | ± 0.045 |
