COMPUVALVE Check

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

If diagnostic results from SYSTEM TESTS indicate a suspect compuvalve, complete the following before replacing compuvalve:

Verify ALT fuel switch status. See THEORY & OPERATION - EEC-V - BI-FUEL article.
Ensure proper communication ability with EEC system between PCM and compuvalve.
Confirm MAP line is not loose, kinked, or restricted.
Check harness and connection integrity.
Ensure EEC system calibration is for current Bi-Fuel code.
Verify battery voltage to compuvalve.
Ensure adequate fuel level at tank sending unit (LPG only) to permit engine operation in ALT fuel mode.
Confirm that fuel filter (LPG only) is not installed backward.
Verify base vehicle does not have a secondary ignition operation concern.
Check for any applicable Technical Service Bulletin.

Common causes of compuvalve misdiagnosis are as follows:

MAP elbow loose.
High FAP from vaporizer malfunction.
Low FAP due to lockoff fault.
Incorrect interpretation of DTCs.
Misfire due to faulty "O" rings.
Compuvalve replaced without checking HPS circuit for high resistance.