odd whining sound near fuel rail

[wes3id]

I just went full corn and did some data logs for my freektune map, and there is a high pitched whining coming from somewhere near the middle of the intake manifold...i'm assuming the fuel rail but it sounds pretty close to the throttle body. has anybody else experienced this? the car drives fine...just not sure if i need to be concerned

[wes3id]

Anybody!!???

[sheston]

You may have to post a video if you can. These cars make way too many "odd" sounds

[wes3id]

Here is a shitty video with the whining.

[MD1032]

That's really high pitched, almost sounds electronic in nature. Try unplugging the electronic spill valve on the HPFP while the car is idling and see if the sound stops (note: this will cause the car to idle rough). It almost sounds like it's coming from the fuel pump.

[wes3id]

Originally Posted by MD1032 That's really high pitched, almost sounds electronic in nature. Try unplugging the electronic spill valve on the HPFP while the car is idling and see if the sound stops (note: this will cause the car to idle rough). It almost sounds like it's coming from the fuel pump.

when i turn the car off it winds down but if i turn it back over to acc, there is no sound except the normal hpfp priming sound. i try to put my ear down to find exactly where its coming from... sounds like it's coming from lower than the hpfp, like near the throttle body area. i cant feel any air bleeding out anywhere or any leaking fluids.

[MD1032]

It could be the throttle body motor going bad then.

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[wes3id]

@atvfreek; any idea's? never heard this before yesterday after i switched over to corn

[Enki]

Pretty sure the throttle body is PWM, which very well could be the sound you're hearing.

[wes3id]

Originally Posted by Enki Pretty sure the throttle body is PWM, which very well could be the sound you're hearing.

excuse my ignorance, but what is "PWM"?

[MS3Shadow]

Originally Posted by wes3id excuse my ignorance, but what is "PWM"?

Pulse width modulation (PWM) is a fancy term for describing a type of digital signal. Pulse width modulation is used in a variety of applications including sophisticated control circuitry. Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial loads such as motors. In addition, PWM is one of the two principal algorithms used in photovoltaic solar battery chargers,the other being maximum power point tracking.

sent from my Nexus 6P

[Enki]

PWM on a motor can cause an annoying resonance in some motors. Case in point:

MazdaSpeed Forums Presents: YouTube

MazdaSpeed Forums Presents: YouTube

[wes3id]

Thanks guys. Why would it start doing that now? it never did before

[Enki]

What did you change?

[wes3id]

Originally Posted by Enki What did you change?

installed a JBR BSD kit, changed oil, si-1 hpfp treatment, switched to e85 and loaded first freektune base map for e85 to take some logs. seems a lot hotter in the engine bay as well...coolant and oil temps are in the norm for me, but my once cold pipe is now pretty hot

[Enki]

Have you checked your oil level?

[wes3id]

yes i did.

[sheston]

Are you having any boost issues? Your comment about winding down, could it be the turbo starting to fail? The sound might travel thru the intercooler and sound like it's coming out of the rubber pipe after the cold pipe, before the throttle body.

You could check for shaft play fairly easily

[wes3id]

what i meant about winding down was, when i turn the car off..the noise dies off slower than the car (like 2 seconds) I'm fairly certain it is not the turbo as it's a different sound. I did check for shaft play yesterday and sad to say...i have maybe 2mm front to back movement. housing inlet looks good, no oil, barely any scratches, blades are good, no smoking.