The tachs in these cars are actually sound pressure level meters. The faster the engine spins the more noise it makes. Move the microphone away from the horn.



Sounds like a classic symptom of a grounding problem to me.

__________________
Dale

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1990 300D 2.5 Turbo -155k
2000 E430 - 103k
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2014 VW Passat TDI SE - 7k Bro's Diesel
2006 E320 CDI - 128k Pop's Benz

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