Re: 20psi boost

[orin@netcom.com (Orin Eman)]

> The Computer goes into open loop when it detects the 2/3 (full throttle) 
> switch closed and then sets the frequency valve to a duty cycle around
>   68% to richen up the mixture under full throttle. Using an expensive 
> portable 4 gas  analyzer I have measured the air fuel ratio to be closer to 12.8 to 1 
> (upstream of the cat convertor) under sustained full throttle at 1.4 bar
> and 1.8 bar boost on the 5000 MC and the later 89 200 MC engines
> with the stock frequency valve duty cycle settings.

As an aside, some benefit can be gained by setting the idle duty cycle low.
If you set the duty cycle to 50% at idle, 68% is only a 18% increase.
Set the idle duty cycle to 40% and now you get a 28% increase at WOT.
(Now I don't know the exact relationship the duty cycle has to the mixture,
but 40% seems to be the accepted setting.)

Scott, what was the idle duty cycle when you made those measurements?


Orin.