Mazda 6 Service Manual: No.4 hard to start/long crank/erratic start/erratic crank

No.3 will not crank

No.5 engine stalls-after start/at idle

Other materials:

Mazda 6 Service Manual: Foreword
Caution When the engine does not start or stalls and the following DTCs are not indicated, go to engine symptom troubleshooting. Note When the immobilizer system is defective, the engine cannot be started. If engine condition is normal but light stays on, inspect for short circ ...

Mazda 6 Service Manual: Mass air flow (maf) sensor inspection
Voltage Inspection Note Perform the following inspection only when directed. 1. Visually inspect for the following on the MAF sensor. Damage Cracks Terminal bends Terminal rust - If any of the above are found, replace the MAF sensor. - If the MAF PID value is out of specifi ...