Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
---|---|---|---|---|---|
5-Volt Reference | P0107, P0452, P0532, P0641 | P0106, P0107 | P0107 | P0106, P0108, P0453, P0533, P0641 | P0106, P0107 |
MAP Sensor Signal | P0107 | P0106, P0107 | P0107 | P0108 | P0106, P0107, P1101 |
Low Reference | -- | P0106, P0108 | P0106, P0108 | -- | P0106, P0108 |
Circuit | Normal Range | Short to Ground | Open | Short to Voltage |
---|---|---|---|---|
5-Volt Reference | -- | 10 kPa | 10 kPa | 104 kPa |
MAP Sensor Signal | 12-103 kPa | 10 kPa | 10 kPa | 104 kPa |
Low Reference | -- | -- | 80-103 kPa | -- |
The intake flow rationality diagnostic provides the within-range rationality check for the mass air flow (MAF), manifold absolute pressure (MAP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.
• | The throttle model describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), TP, intake air temperature (IAT), and estimated MAP. The information from this model is displayed on the scan tool as the MAF Performance Test parameter. |
• | The first intake manifold model describes the intake manifold and is used to estimate MAP as a function of the MAF into the manifold from the throttle body and the MAF out of the manifold caused by engine pumping. The flow into the manifold from the throttle uses the MAF estimate calculated from the above throttle model. The information from this model is displayed on the scan tool as the MAP Performance Test 1 parameter. |
• | The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input. The information from this model is displayed on the scan tool as the MAP Performance Test 2 parameter. |
• | The fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model. The information from this model is displayed on the scan tool as the TP Performance Test parameter. |
The estimates of MAF and MAP obtained from this system of models and calculations are then compared to the actual measured values from the MAF, MAP, and the TP sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.
MAF Performance Test | MAP Performance Test 1 | MAP Performance Test 2 | TP Performance Test | DTCs Passed | DTCs Failed |
---|---|---|---|---|---|
-- | -- | OK | OK | P0101, P0106, P0121, P1101 | None |
OK | OK | Fault | OK | P0101, P0106, P0121, P1101 | None |
Fault | OK | Fault | OK | P0106, P0121, P1101 | P0101 |
OK | Fault | Fault | OK | P0101, P0121, P1101 | P0106 |
Fault | Fault | Fault | OK | P0121, P1101 | P0101, P0106 |
-- | -- | OK | Fault | P0101, P0106, P1101 | P0121 |
OK | OK | Fault | Fault | P0101, P0106, P0121, P1101 | None |
Fault | OK | Fault | Fault | P0101, P0106, P0121 | P1101 |
-- | Fault | Fault | Fault | P0101, P0106, P0121 | P1101 |
• | DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0335, P0336 are not set. |
• | The engine speed is between 400-6,400 RPM. |
• | The IAT Sensor parameter is between -7 and +125°C (+19 and +57°F). |
• | The ECT Sensor parameter is between 70-125°C (158-257°F). |
• | This DTC runs continuously within the enabling conditions. |
The powertrain control module (PCM) detects that the MAP sensor pressure is not within range of the calculated pressure that is derived from the system of models for more than 0.5 second.
• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
• | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
• | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
• | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
• | Clear the MIL and the DTC with a scan tool. |
Important: Verify that the engine is in good mechanical condition before continuing with this diagnostic.
• | Verify the integrity of the air induction system by inspecting for the following conditions: |
- | Any damaged components |
- | Loose or improper installation |
- | Improperly routed vacuum hoses |
- | Any vacuum leak |
• | Verify that restrictions do not exist in the MAP sensor vacuum source. |
• | Verify that restrictions do not exist in the exhaust system. Refer to Restricted Exhaust . |
• | A skewed or stuck engine coolant temperature (ECT) or IAT sensor will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistance . |
• | The BARO that is used by the PCM to calculate the air flow models is initially based on the MAP sensor at ignition ON. When the engine is running, the PCM will continually update the BARO value near wide open throttle using the MAP sensor and a calculation. A skewed MAP sensor will cause the BARO value to be inaccurate. Use the scan tool and compare the BARO parameter at ignition ON to the Altitude vs. Barometric Pressure Table. Refer to Altitude Versus Barometric Pressure |
• | A skewed MAP sensor will also cause the first and second intake manifold models to disagree with the actual MAP sensor measurements. Use the scan tool and compare the MAP Sensor parameter to a known good vehicle, under various operating conditions. |
⇒ | If the voltage is less than the specified range, then test the circuit for a high resistance or a faulty PCM. |
⇒ | If the voltage is more than the specified range, then test the circuit for a short to voltage or a faulty PCM. |
⇒ | If the MAP Sensor parameter is more than 12 kPa, then test the MAP sensor signal circuit for a short to voltage or a faulty PCM. |
⇒ | If the MAP Sensor parameter is less than 103 kPa, then test the MAP sensor signal circuit for a high resistance or a faulty PCM. |
⇒ | If the resistance is more than 5 ohms, then test the circuit for a high resistance or a faulty PCM. |
Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for PCM replacement, setup, and programming |