Power supply (battery, fuse connection, fuses).
Body grounding.
Ignition system (spark plugs, high voltage wires, ignition coil).
fuel system (fuel lines, fuel filters, fuel pump).
Exhaust emission control system (PCV system, EGR system, leakage).
Ignition installation.
CAUTION: Malfunctions of the electronic control system are often caused by poor contact wire connections. Therefore, you must first check all connections.