Component Location
General Description
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 by 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 MAPS output and calculated MAPS value while enable condition is met. If the acutal MAP value is higher than Maximum threshold or lower than Minimum threshold for a pre-determined time, PCM determines that a fault exists and a DTC is stored.
DTC Detecting Condition
Item | Detecting Condition | Possible Cause |
Case 1 | DTC Strategy | Circuit Range/Performance Problem (During acceleration)
| Dirty air cleaner Oil Cap or Dipstick missing or not installed correctly. Air leak in intake system Contact resistance in connectors. Faulty MAPS or TPS
|
Enable Conditions | Engine RPM > 1000 rpm 10 V = Battery voltage = 16V Signal change > 12°/sec
|
Threshold Value | MAP(Model) > 0.9*ATM. But, MAP(Measured) < 0.6*ATM Deviation value of fuel trim control > 20% or < -20%
|
Case 2 | DTC Strategy | Circuit Range/Performance Problem
|
Enable Conditions | Engine RPM > 1000 rpm 10 V = Battery voltage = 16V
|
Threshold Value | MAP(Model) - MAP(Measured) > 280 hPa Deviation value of fuel trim control > 20% or < -20%
|
Diagnostic Time | It depends on the driving conditions.
|
Mil On Condition | 2 Driving Cycles
|
Diagnostic Circuit Diagram
Signal Waveform & Data
As often as possible, the MAPS signal should be compared with the TPS signal. Check whether the MAPS and TPS signals increase at the same time when accelerating. During acceleration, the MAPS output voltage increases; during deceleration, the MAPS output voltage decreases.