The amount of intake air flow must be inputted to ECM in order to determine the fuel injection quantity. To measure the pressure inside of intake manifold, MAFS is used at idle and MAPS is required at accelerating. MAPS(Manifold Absolute Pressure) calculates the amount of air indirectly as measuring the pressure inside of intake manifold. This system is called a Speed-Density type.
MAPS transfers analog output signal which is proportional to the change of intake manifold pressure, then, with this signal and RPM, ECM calculates the amount of intake air flow. The 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 output by the transformation of diagphragm 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 ., ECM sets P1106.
Item | Detecting Condition | Possible cause | |
DTC Strategy |
•
Monitor the signal of MAP sensor | 1. Poor Connecting 2. Short to battery in signal circuit 3. Open in ground circuit 4. Faulty MAPS 5. Faulty ECM | |
Enable Conditions | Case 1 |
•
No TPS Active Fault Present
•
Engine Running Time > 10sec.
•
Engine Speed ≤ 2500rpm
•
Throttle Position ≤ 30% | |
Case 2 |
•
No TPS Active Fault Present
•
Engine Running Time > 10sec.
•
Engine Speed > 2500rpm
•
Throttle Position ≤ 40% | ||
Threshold value |
•
Intermittently MAP Signal > 4.5V | ||
Diagnosis Time |
•
Contineous (More than 2sec. failure for every 4 sec. test) | ||
MIL On Condition |
•
DTC only(NO MIL ON) | ||
Pressure(kPa) | Voltage(V) |
20 | 0.79 |
46.66 | 1.84 |
101.32 | 4.0 |
Fig.1) Normal waveform of MAPS & TPS with acceleration.
Fig.2) Normal data of MAPS at idle.
