Electrical whine from engine bay - NC

Technical Area Engine, Transmission, Exhaust etc
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  1. My model of MX-5 is: NC 2.0 Launch Edition
  2. I’m based near: Scotland
  3. I’m looking for technical help or recommendations on: Electrical noise from engine

Hey all. Today while getting the car out of hibernation and ready for the season I noticed a fairly loud electrical whining noise coming from the engine bay. It appears to be coming from the intake side, Bethan’s somewhere under the manifold although it’s difficult to say exactly where.

I can only hear it when the car is in the second ignition position, not the first, and turning on and off the fans and AC doesn’t change it

I took a video of it:

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Does pressing the throttle pedal change the noise?

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Thanks for the reply.

I can test this, but just to be clear, the noise is with the engine not started.

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The throttle butterfly should still move just with ignition on (II), like a cable throttle. It won’t move in the accessory position (I). It isn’t clear from your sound clip but I suspect it is the throttle valve motor holding the throttle in position.

In a nutshell, the throttle butterfly is spring loaded to a fail safe position to give about 2000rpm if the motor fails. The throttle motor has to pull the butterfly towards the closed position, against spring tension at startup and idle then open it in relation to throttle pedal position.

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Right. I understood some of that, but not all. :rofl: It’s certainly in the right spot for the throttle.

I’ll test in the morning and come back to you if that’s ok.

Thanks again for the help!

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Morning,

I’ve tested this today and the noise does not stop when I use the throttle while in the II position. I can hear the valve opening and closing but no change in the noise.

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I would agree with the throttle body.

Just an idea, get a cheap second hand one off eBay for about £30 which 9 times out of 10 will carry some form of warranty.

Swap them over and see if it fixes the issue? :crossed_fingers:

I reckon you probably wouldn’t get much change out of £5-600 for a new Mazda one.

Nothing to loose really and that would be what I would do.

Just an opinion and good luck. :+1::slightly_smiling_face:

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That’s not a bad shout. I wonder if disconnecting it would be a first good step? Might have a look at that tomorrow when I get a chance.

For now its not causing any ill effects when using the car, but I imagine that it could end up stranding me if it fails completely.

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