Throttle Plate Control

[Joel A. Robinson]

On Sun, 14 May 1995, Lawrence S. Harris III wrote:
> 
> I'm surprised that with an EFI system that people wouldn't consider 
> cutting fuel rather than spark.  

> Has anyone out there played with cutting fuel rather than spark?  If no 
> one uses this method, why not?

My '84 Colt Turbo cuts fuel when boost rises above 9.5 psi.  The fuel cut 
is very abrupt and though it may protect the engine, it probably puts 
unnecessary stress on the drivetrain.  Sometimes I hit the fuel cut 
when I pass...foot to the floor, driving in the oncoming lane and 
suddenly..WHAM it cuts fuel.  You can feel the transmission lurch  and 
the motor mounts strain in the gear shifter.

I a more progressive fuel cut approach would be a lot better, and the 
same for a rev-limitter.

Does anyone know what effect cutting fuel at peak boost or peak rpm has 
on detonation?  Is their any risk of damaging the engine by running too 
lean for a split second?  Which is more dangerous:  Cutting fuel 
(suddenly or progressively) and leaning out or cutting spark and 
backfiring?

Thanks,

Joel Robinson
robinj at src.usbm.gov