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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
A wide band O2 is a great idea on a CIS 930. Alternately a EGT. Especially if upgrading and or if planning any track days.

Alternately verifying AFR's on a dyno is often adequate as we tend to run CIS a little fat as compensation for it's inhearnt weaknesses.

For example, CIS dose not have much ability to compensate for changes in environmental conditions such as changes in air density caused by temp or altitude so one might have fair AFR's in the summer but then run lean in the cold.

If you still have stock cams and ports you should be ok as to fueling but you may be near the limit with a stock WUR settings to support your new levels of HP. Again you should check the upper RPM under boost for the potential for going lean however, you probably will not spend much time up there. Typically with the mods you are talking about one would set the CO richer than stock to about 3%.

The D-WUR alows one to fine tune the AFR's under different operating conditions. For example, if you set your CO at 3% with a stock WUR to have enough fuel up top and to improve off idle acceleration you would be a little rich on cruse. With the D-WUR you can dial in ideal AFR's on idle, curse, acceleration, and get up to about one point more fuel in the upper RPM's when making more HP. As noted, this takes fine tuning to run closer to ideals but with an add on wide band O2 is should not be difficult.

I have done the electronic modification of control pressures including dialing it in on a dyno and the street for a significant improvements but my next CIS 930 will be more old school, all mechanical, and with probably just an EGT.
Old 12-26-2009, 10:34 AM
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