By Rich928 - Sat Jun 06, 2026 9:18 pm
- Sat Jun 06, 2026 9:18 pm
#343847
More older Porsche 928s are coming back to life. I'm assisting an independent shop with an early 1980s Porsche 928 that has L-Jetronic fuel injection. A known good tester L-Jet module was sent and the engine will not start, so more diagnostics is needed. I created this overview to assist such diagnostic testing.
Where the newer 1985 - 1995 928s (as well as Euro/ROW 1984) use digital based control where the engine can start with no connection to the coolant temperature sensor and mass airflow sensors, the earlier L-Jetronic must have valid voltages at the module before injection will start. I outlined these connections and how to verify the circuits.
Where the newer 1985 - 1995 928s (as well as Euro/ROW 1984) use digital based control where the engine can start with no connection to the coolant temperature sensor and mass airflow sensors, the earlier L-Jetronic must have valid voltages at the module before injection will start. I outlined these connections and how to verify the circuits.
You do not have the required permissions to view the files attached to this post.
- By hernanca
- By Gary Knox
- By Sazerac