>| Should you set the CO (mixture) adjustment after installing a new O2 sensor? I think it depends on whether it had been adjusted as the old O2 sensor got replaced. This is just my own reasoning derived from the vanagon Bentley, the Probst FI Bentley and my own dabbling with elecrtonics - I am no expert on any of this so be forwarned, do your own logical checking, and research. The fi system is based on electrical signals of parts that have specified tolerances in their resistances. In a system with multiple parts these variations add up, and there needs to a way to tune the system to these differences as the system ages and parts are changed. Basicly I think that screw is a small pot that I assume changes the resistance through the air meter, air temp sender (I believe the digifant has one of these in the air flow meter), or just through the 4th pin on the AFM connector (I can only think of 3 pins being necessary for the afm and potentially an air temp sender). This change in one of the signals changes the point in the mappings that the ECU uses. It is used to adjust the baseline for the air fuel mixture around which the O2 sensor will attempt to keep within limits as demands on the engine change as specified by those mappings. One could check some of this against the Bentley as I don't have it within 40 miles of where I am correctly sitting ;) Now how does the O2 sensor then correct for large vaccuum leaks? I don't know... Even if that isn't right - it's safest (but of course more expensive to get the CO level adjusted). dave |
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