I have a 2008 Toyota Tacoma and had S-9 noise when running mobile. I was
able to reduce it greatly by grounding the tail pipe at the exhaust exit to
the truck frame with a 1 inch strap and stainless steel hose clamp. Used a
quarter inch bolt on the frame side.
The tail pipe is hung on rubber straps and was acting like an antenna for
engine noise. As a test, you can connect a clip lead between the end of
the tail pipe and frame and see if it has any effect.
I also tried various other groundind staps for the hood, front quarter
panels, and roof but they had minimal impact.
I use the mobile set-up for producing a RFI Map so maintaining a low noise
floor is important. The S meter usually runs between S-2 and S-4 depending
on engine speed.
Jeff, W4DD
On Wed, Sep 16, 2020, 2:13 PM David Gottschalk <dave@highredline.com> wrote:
> Howdy folks,
> I'm looking for some help and guidance in next steps I can do to
> resolve a mobile noise issue I have. I'm stumped and not really sure what
> else to try. I have a 1997 Toyota 4runner, and a 2003 Toyota Tacoma. Both
> of them make horrible noise when the engine is running. After some initial
> investigation, I thought it might be a bad coil pack/wires or even spark
> plugs. I replaced all three of those with factory new parts on the Tacoma,
> and it still makes this noise. It totally wipes out AM broadcast band to
> about the 2m band. If anyone has experience with an issue like this or, any
> idea for other things to try I'd appreciate it greatly. Below is a video of
> the noise in my Tacoma, but this exact same noise happens in both cars. It
> is radiated from something, not conducted as the radio was running off
> battery (as you can see in the video).
>
> https://www.dropbox.com/s/hb0wmc2jyzm4d5n/2020-07-31%2017.35.36.mp4?dl=0
>
> 73,
> David
> KN4ZKT
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