In article ,
Dave wrote:

Telamon wrote:
In article ,
Dave wrote:

On Tue, 15 Jul 2008 18:14:47 +0000, D Peter Maus wrote:



I've never had trouble with it. Ignition noise is a PITA to remove.

I have switching power supplies all over the house. Including the UPS
for the buildling. I don't get noise in my radios from the UPS.

But if I fire up my motorcycle, whole bands become unlistenable. I
never did get all the ignition noise out of the radio on my 308. Even
the Caravan had some ignition noise.
Are diesels still quiet (electrically)?

Yes.

Sorry pal, but after I got some rude replies from the Great Lakes
Dynamic Duo I did some research and my suspicions were confirmed:

"With the use of high pressure injectors it takes a 100V
pulse to actually fire the injector. There is also some
back EMF from the solenoids as the pulse ends and the
solenoid opens. Unfortunately the diodes to clamp the back
EMF are usually located in the Injector Driver Module (IDM)
where they protect the IDM from the back EMF transient. By
that time the couple feet of wire connecting the two has
radiated the emission.

In my 95 7.3L Power Stroke, the back pulse significantly
exceeded 1000 volts. That's more than "some" backpulse, hi
hi.

Place the clamping diodes at the injectors, shield the
wires, and round the edges of the pulse that fires the
solenoid and the problem should subside. Not recommended
for appliance operators/drivers or vehicles in warranty.

The shields inside the Ford Diesel cables were grounded only
at one end. I grounded them at the solenoid ends to valve
cover bolts, and did other grounding to the vehicle. I was
always afraid to clamp the injector solenoids because any
back-pulse clamping would slow release times significantly.
As far as I could tell, NOTHING clamped the solenoids.

My brand new PSD appears to have the same problem.

Anything CAN be badly engineered to point that it will cause problems.
Everything written above can be very effectively mitigated if any
thought was applied to EMI/RFI. Proper RF bypassing of solenoids is
well known.

The high voltage spark in a internal combustion engine is broadband and
it is very difficult to create a small RF current loop to prevent
radiation from it.

--
Telamon
Ventura, California