E46

Are you saying there is no fault codes in the ecu or launch not connecting to ecu.

To determine if your Launch is connecting or not, go into Live Data (Data Stream).

• If you can see parameters like Coolant Temperature or Engine RPM changing while you crank, the scanner is connected and the ECU simply has no stored fault codes.
• If you cannot enter the module or read live data, it is not connecting (check your OBDII fuses in the glovebox).

Since you have confirmed Spark and Fuel at the rail, but no codes, check the following:

1. Fuel Pressure (Critical)
Seeing fuel at the rail is not enough. You need 3.5 bar (50 PSI) of pressure. The car will not start with 20 PSI, even though fuel will spray out if you press the Schrader valve. Hook up a mechanical gauge to verify.

2. "Bore Wash" (Lawnmower Syndrome)
This is very common on the M54 engine. Did you recently start the car cold, move it a short distance (like out of a garage), and turn it off immediately?

• This causes the injectors to flood the cylinders, washing the oil off the piston rings and causing a loss of compression.
• Test: Remove the spark plugs. If they are soaking wet with gas, dry them off (or replace them), put a teaspoon of oil in the cylinders to restore compression, and try starting with the gas pedal held to the floor (Clear Flood Mode).

3. Crankshaft Position Sensor
Usually, if the Crank sensor is dead, you won't get spark. However, sometimes a failing sensor gives a weak signal that allows spark but incorrect timing. Watch the RPM on your Launch scanner while cranking. It should read between 150-200 RPM. If it stays at 0, your Crank sensor is dead.

4. Massive Vacuum Leak
Check the rubber intake boots (specifically the lower one connecting to the throttle body). If it is torn open, the MAF readings will be wrong, and the car may not start. Unplug the MAF sensor and try to start it; this forces the ECU into a default map.