Oh, one more thing on the "closed loop" topic--none of the 914 stock EFIs uses an O2 sensor.
If you look at the stock 2.0 air cleaner setup, you can see how that might be some restriction to incoming air. It has to go into the snorkel, then make a 90-deg turn up into the main "box", then through the filter,
then a 90-deg turn to go out toward the throttle body, then a third 90-deg turn to go down into the throttle body. A cone filter right on top of the TB would make for zero turns--probably less restriction.
As for the other hoses, none of them have vacuum under normal operating conditions. The one from the AAR gets vacuum when the engine is cold, and the one from the decel valve has vacuum under "overrun" conditions.
Now consider what happens if those are open to the air (but filtered air, of course!). The air gets sucked in, which raises the air pressure in the manifold. (Or lowers the vacuum, same thing.) The MPS detects this change in pressure, and adds fuel. The result? More air and more fuel--a reasonably correct mixture, and an engine that is turning more RPMs than it would otherwise. (Mostly noticeable at idle.)
Which is exactly what you want to happen with the AAR and DV.
The L-jet system has to have those things fed by filtered air that has been
measured by the Air Flow Meter. So in L-jet's case, you have to tap into something between the AFM and the TB.
--DD
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Pelican Parts 914 Tech Support
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http://www.pelicanparts.com/gallery/Dave_Darling