October 30: LEMON manuals on a temporary server, it is slow and having issues, download the manuals you need! Later in November we will switch back to the fast server.

Poor Fuel Mileage

Ensure base timing and timing advance system is functional.
Ensure fuel system pressure is correct.
Check cold start valve for leaking (engine warm).
Check airflow sensor voltage output.
Check air induction system for leaks.
Check fuel injector operation.
Check engine coolant temperature sensor operation.
Check oxygen (O2) sensor operation.