[HQRP] Diesel Noise - Ford PowerStroke

[Ron Sparks]

Quite some time ago I posted a query as to why my F-350 Diesel was creating
about 2-5 S units of rpm related noise.  A big clue was when Paul Gobel told
me his was the same and that the injectors used high voltage to trip.

That was absolutely right!  The doggoned things use 110 volts (yes 110!) to
fire, due to the very high pressures involved.  Basically each injector is a
miniature hydraulic pump with crankcase oil at several hundred pounds (about
600 psi) in the main supply rail.  The 110v PWM signal then opens a valve to
let this high pressure oil act on the back side of a piston which then
compresses the fuel until a spring loaded poppet opens at about 2700 psi and
injects direct into the cylinder.  All this is nicely described for all you
Ford diesel owners at: http://www.intellidog.com/dieselmann/injector.htm

As for the QRM.  I got rid of one S unit by putting a ferrite bead around
the cable bundle from the computer.  I have gotten rid of another S unit by
improving grounds (especially between the hood and chassis).  As to the last
one or two S units -- I now have to find a way to shield the high voltage
wires to the injectors.

More later -- happy rovering,

Ron, AG5RS