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moving on to a less disruptive issue, still DBW but this is consistent "hum" of the throttle body motor cycling. Elite 2500 on a Ford Mustang. issues is prevalent with stock throttle body or the BBK ported one. Motor is a built 3.5 ecoboost with 3.7 heads, procharged. Wiring is a Haltech 2500 plug & play for coyote with a few small tweaks for plugs being different on a couple sensors. attached is the pattern on the motor drive wires if back pinned with a picoscope- what makes this "noise". moving cables around doesn't affect it. it makes the noise even if there's pedal command to open. Elite 2500 is wired directly to the battery for power and ground. stout motor grounds. Everything is still in the haltech sheath so it looks shielded. if it's not noise - is there a setting in the 2500 to dull the frequency?
The motors in the DBW servos are driven at a high frequency (not sure of the Haltech but MoTeC uses 8kHz) when being controlled by the ECU, is this what you are hearing?
8khz would be hard to hear. this is in the 50-100hz range and the throttle blade vibrates in sync with it. very audible, like a cicada. sounds like the frequency needs to be increased? not seeing a way to do that, tho.
8kHz is easy to hear when the engine is not running, I can always tell when one of my co-workers is testing a DBW servo as the tone travels. Some knock sensor will also pick it up.
Uh, Steven probably nailed it - I don't think you quite understand sound frequencies.
50-100Hz is a deep tone, in the bass range - Cicadas are a lot higher but still well within the auditory range of most people and 8kHz is almost the same as the cicada's sound for most people's hearing. "The sound of each individual cicada was separately analyzed by MATLAB Software, and the size of its main parameter (i.e., dominant frequency) was determined and recorded. The results showed that this cicada species have a mean dominant frequency of 9.121 kHz." (not my bold!)
That said, I believe there can be problems with the servo for some Ford model's with variable tract intakes - could this be the case?
good points from you both. the experiences I have match the science of this being audible in that 8khz-9khz range. the intake is a fixed design, a basic plastic intake with the throttle body bolted to the snout. the sound and wave form look deliberate, it makes sense that the blade is humming/clicking in response as the haltech pulses to maintain position. Curious if Ford uses a higher frequency or a steady voltage that isn't audible? regardless it doesn't appear to be hurting the motor just very noticeable when the engine is off.