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The wetter is nice early this year, so I took the Evora out for a spin, when back I noticed a humming sound out of the engine bay. It is from the throttle body. Checked all the connections (also position sensor at the pedal) and the battery but is stays. Gas is responding normal. Here is a video, contact on, engine out. Is this the beginning of the end?

 

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The wetter is nice early this year, so I took the Evora out for a spin, when back I noticed a humming sound out of the engine bay. It is from the throttle body. Checked all the connections (also position sensor at the pedal) and the battery but is stays. Gas is responding normal. Here is a video, contact on, engine out. Is this the beginning of the end?



https://youtu.be/Yiao-lD2phE
Mine makes the same sound key on, engine off. Doesn't seem to affect anything yet.

Sent from my SM-G950U1 using Tapatalk
 

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Electronic throttle work by using a "Pulse Width Modulated" (PWM) signal. This means that the ECU very quickly cycles between on and off, and the amount of time spent during the "on" phase determines how much power gets transmitted. They tend to run around 1-3kHz and can be very audible. What's fun is you can actually play music with the throttle by varying that frequency, but your office mates get annoyed very quickly (I used to right the code for these in American Le Mans and GrandAm)
 

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Discussion Starter #4
Thank you guys for your quick reaction, watched some other videos with electronic throttles, the same annoying buzz. Never noticed the sound, maybe I thought it was the fuel pomp.
 

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Yeah, a higher frequency can make it completely silent, but the electrical engineers will claim that it can shorten the life of the power electronics. Plus, it is actually kinda helpful to make a little noise if you are ever troubleshooting a high idle.
 

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2005 Elise LSS Saffron Yellow
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Just in case you think this only happens with drive by wire throttle bodies, lots of cars use pulse width modulation to control the idle air controller. You can hear the idle air controller whining in a quiet enough engine bay, especially if the car is a MAP car and you have the zip tube off for some reason.

Our '99 Grand Marquis family truckster/tow vehicle uses a single coil PWM controller that depends on a spring and damper system to pull the IAC shut against the coil. As the damper bushing in the IAC stiffens up, it gets into a fun state generally called 'moosing' (as in 'sounds like a moose') when at fast idle. In that state, the IAC partially sticks, so the controller hits it with a blast of 100% duty cycle to force it open further, then it overshoots, and the controller goes to near zero duty cycle and it overshoots, resulting in an oscillation in the intake tract that does indeed sound a little like an ungulate's mating call.

Yes, I've been meaning to fix that, but it hasn't been very high on the priority list. A blip of the throttle usually kicks it out of the oscillation mode, and it never does it once the car is warmed up.

Injector click can be quite loud as well - a useful diagnostic if you have a hard miss and are trying to figure out if you have an injector/ECU/wiring problem or an ignition problem. I actually use my old mechanic's stethoscope a lot more these days than I did with carbs and distributors because of the diagnostic utility of these noises.
 

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shay2nak
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I definitely hear it in the exige. At first I didn't know what it was. The frequency seems to increase with RPM, especially at WOT.
 

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shay2nak
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That's not the throttle PWM since the PWM is on a fixed frequency. The tone may change, but not the note.
I see. I will pay closer attention next time I drive.
 

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I see. I will pay closer attention next time I drive.
To hear the throttle, you should be able to have the engine off, key on, and have someone move the throttle while you listen near the throttle.

Engineers use an algorithm though that converts the driver's input input throttle angle through a whole ton of maps that look at things like gear, vehicle speed, rpm, etc, so it is entirely possible that the throttle won't move until the engine is on. I don't know exactly how the Evora or Elige are set up, and they are probably all a little different throughout the years and options (ie IPS or manual or SC or NA). It's easy enough to just try and see though.
 

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Illegal Alien
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To hear the throttle, you should be able to have the engine off, key on, and have someone move the throttle while you listen near the throttle.

Engineers use an algorithm though that converts the driver's input input throttle angle through a whole ton of maps that look at things like gear, vehicle speed, rpm, etc, so it is entirely possible that the throttle won't move until the engine is on. I don't know exactly how the Evora or Elige are set up, and they are probably all a little different throughout the years and options (ie IPS or manual or SC or NA). It's easy enough to just try and see though.
Lotus Evora throttle plates move in relationship to pedal travel through a 2D map of pedal input vs plate angle output. Normal and Sport have different maps both are non-linear however the Sport map is much more so, on Phil's tune to my '12 Evora done back in 2016 using his BOE software bth my maps were changed to the same table and if memory is right we linearized the curve even more. Throttle plates will also move to ECU commands based on traction control, accessory loads, A/C, idle, maybe intake or water temps, etc, but they don't change just because of rpms, and vehicle speed .. its drive by wire but not overruling driver
 
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