Ditto...
Bonding on the Ford is good enough when the vehicle is new but after one
winter the exposed bonding connections start to corrode. Also, the bonds
exist only by virtue of the screw thread into the sheet metal or frame. I
removed all the factory bonds I could find and cleaned the metal, applied NO
OX, then installed large straps; even put one on that nice stainless steel
tail pipe.
On the Explorer there are bonds between the frame rail and the chassis which
sits on rubber bushings and there is a single bond from the firewall to the
hood; no bond from the battery to the frame rail. There is a bond from the
engine to the negative of the battery and a short bond from the battery to
the chassis...sort of resembles a single point ground, but you have to work
your way from the sheet metal to the frame rail. Its been five years now
but I think I saw as much as ohms between the negative of the battery and
the frame rail when I first started adding bonding straps.
Here is a quote from a post I made back in 2005 ( you can search for more
comments by going to the archives and look for "Ford Sport Trac". There is
a mistake in the comments I made...the shielded spark wires removed all the
ignition noise on the FT-857 w/NB on and engine idling. However, when
accelerating the igniter overwhelmed the ability of the NB to reduce the
noise...thus the igniter has to be shielded.
If the weather is good or you have a garage reducing the noise is a fun
project. You can see the results of your efforts.
------------------------------------------------------------------------------------------------------------------
One of the main RFI radiators in the Ford Sport Trac variable voltage
ignition system is the primary wiring. Ford and probably most other
manufacturers run all the primary wiring in one harness. The 12 VDC wires
that feed power to the controller that drives the ignition coils
sees significant RF pulses from the controller which are then radiated in
what is a large loop (sort of like a ground loop). Part of the problem is
that the low voltage + wire is run all over the engine with no adjancent
negative wire which allows for no possibility for balanced line which would
attentuate RFI.
The solution for the Ford is the run a dedicated low voltage line from the
fuse panel to the controller. Using Marine low voltage wire (+/-) cable
solves the low voltage wire RFI.
In the case of the Ford it uses an igniter with spark wires. The secondard
wires are shielded with 1" silver tinned braid. The engine is so quiet now
that I can hear the sensor clicking on the ABS system but I can also hear
the low power AM radio used for parking at National Airport some ten miles
away.
The gas tank noise is solved with a corcom AC line filter mounted as close
to the tank as possible. In the Ford the filter is actually mounted inside
the gas tank (a warrantee repair or $350 after warrantee). If you mount the
external filter be sure to bond the metal case to the frame rails.
Good Luck,
dave
wa3gin
----- Original Message -----
From: "Jim Brown" <jim@audiosystemsgroup.com>
To: <rfi@contesting.com>
Sent: Thursday, October 28, 2010 7:58 PM
Subject: Re: [RFI] AM radio RFI from 2010 Ford Escape
> Chassis bonding in some vehicles is REALLY AWFUL...
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