1. Fuel Delivery:
- Double-check to ensure that there is proper fuel delivery. Verify if there is fuel reaching the injectors or carburetor.
2. Spark Check:
- Start by checking the ignition components, including the spark plugs, spark plug wires, and distributor (if equipped). Make sure the spark plugs are firing properly. Remove one spark plug, connect it back to its wire, and hold the base to the cylinder head while someone cranks the engine. You should see a spark if the ignition system is functioning correctly.
3. Error Codes:
- You mentioned performing the stomp diagnostics and retrieving error codes. The stomp test is a basic method to retrieve trouble codes from the car's on-board computer. Each code is represented by a series of flashes. You can use a diagnostic fault code chart specifically for your BMW 735i's model year to interpret the codes you obtained.
4. Engine Management System:
- Check other components related to the engine management system, such as the ignition coil, ignition module, and crankshaft position sensor. These components can affect the spark generation and overall engine performance.
5. Computer Diagnostics:
- Consider using a more advanced diagnostic tool or take the car to a qualified mechanic equipped with proper diagnostic equipment. Modern vehicles have complex computer systems that control various functions, and advanced diagnostics can provide more detailed information about potential faults.
6. Electrical Connections:
- Ensure that all electrical connections, including battery terminals, are tight and free of corrosion. A faulty connection can interrupt power supply to critical systems.
7. Fuel Pressure:
- Check the fuel pressure to make sure it meets the specifications for your vehicle. Insufficient fuel pressure can prevent proper starting.
8. Immobilizer System (if equipped):
- Some BMW models have immobilizer systems that prevent unauthorized engine starting. Make sure the system is functioning properly and is recognizing your key or remote.
9. Air Intake:
- Verify that there are no restrictions in the air intake system, such as clogged air filters or obstructions in the intake ducts.
10. Timing Belt:
- If your BMW has a timing belt, check its condition. A worn or snapped timing belt can prevent proper engine operation and cause starting issues.
Remember that diagnosing automotive issues can be complex, and it's advisable to consult a professional mechanic if you are not comfortable performing these tasks yourself.
