Mass Airflow Sensor
- Visually check MAF sensor for cracks or damage. If any damage is present, replace MAF sensor. If MAF sensor is okay but PID values or PCM terminal voltage is out of specification, check for open or short circuit. Disconnect PCM harness connector. Connect 104-Pin Breakout Box (49-UN01-130) on all models except Millenia or Adapter Harness (49-TO18-905) on Millenia to PCM harness connector and then to PCM. Turn ignition switch on. See Figure
. Connect DVOM to appropriate PCM terminal. See PCM TERMINAL IDENTIFICATION
table.PCM TERMINAL IDENTIFICATION
Application Terminal No. Miata 4X Millenia 3E MPV, Protege, Protege5 & 626 88 - See MASS AIRFLOW (MAF) SENSOR VOLTAGE table. If voltage is not as specified, check continuity of each circuit between MAF sensor, main relay and PCM. See WIRING DIAGRAMS article. Repair or replace as necessary. If continuity is present in all circuits, replace MAF sensor.
MASS AIRFLOW (MAF) SENSOR VOLTAGE
| Model/Condition | Volts | ||
|---|---|---|---|
| Miata | |||
| Ignition On | 0.9-2.0 | ||
| Idle | 1.7-2.4 | ||
| Millenia | |||
| 2.3 | |||
| Ignition On | 1.3-1.5 | ||
| Idle | 1.5-3.0 | ||
| 2.5 | |||
| Ignition On | 1.0-1.5 | ||
| Idle | 1.5-2.5 | ||
| MPV | |||
| Ignition On | 0.0-0.1 | ||
| Idle | 0.5-0.8 | ||
| Protege & Protege5 | |||
| Ignition On | 0.6-2.0 | ||
| Idle | 0.8-2.2 | ||
| 626 | |||
| 2.0L | |||
| Ignition On | About 0.2 | ||
| Idle | 0.5-1.1 | ||
| 2.5L | |||
| Ignition On | Less Than 1.0 | ||
| Idle | 1.0-2.0 | ||