Ignition Systems

WARNING: This page is about a different car, the 2002 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Compressed Natural Gas (CNG) or Liquefied Petroleum Gas (LPG) fuel burns slower than gasoline under normal operating conditions. The compuvalve sends a signal to PCM to advance base vehicle spark timing by 0-15 degrees to improve driveability and emissions of vehicle. PCM may or may not advance spark timing at idle depending on calibration. For additional information, see IGNITION SYSTEMS in THEORY & OPERATION - EEC-V - GASOLINE & NGV article.

Bi-fuel systems operating in alternative fuel mode (CNG or LPG) are gaseous-type fuel systems that require a higher spark plug firing voltage to ignite fuel and puts a higher load on vehicle ignition system. A secondary ignition system may not operate well or may exhibit problems when running on alternative fuel; such as backfiring or stalling, even though no problems exist while running on gasoline.