GT86 strange engine sound after hard driving

[Krunsy]

Hello everybody! Just got the car a month ago, it’s an 2013. automatic. The vacuum pump is rattling (common issue as I've heard), and I’m waiting for the part to arrive so I can change it. However, there’s been another weird sound, I simply can’t figure it out if it’s coming from the vacuum pump, or it’s something fuel-related or something else.

So long story short, this sound happens only when I floor the car for a brief moment (usually if I’m standing at a red light and it turns to green) to my house or any time I drive it a bit harder. The noise vanishes after 10-15 seconds of idling and it sounds completely normal. My conclusion is bad fuel. Does anyone have any idea what it might be? Doesn’t come from the bottom end so I think it’s not rod knock as this happens since I got the car. I thought it’s either vacuum pump or fuel, but more like fuel since the noise comes from the fuel-pump side of the engine.

Here are some examples:

video 1 - (the noise is better heard live than on video): Gt86 engine noise #1

video 2 - you can really hear it on this one: Gt86 engine noise #2

ps. The videos are recorded on the same day

As for more information, the car has 114k kilometres, previous owner serviced it regurarly, the noise literally randomly comes and goes if driven hard, cold starts are completely fine, the car in park revs to red line completely normal without hesitation/knocks in rpm-change, so it’s very strange. The noise comes from the top endwhere the fuel pump is, as I can hear.

Also, reviewing some of the forum threads, I’ve been scared to death of rod knock, so if someone can give me advice on how to prevent it, it will be much appreciated, and overall tell me if the engine sounds good
Thanks in advance!

[humfrz]

Welcome to the gang -

Sounds like an FA-20 engine running to me - but my ears ain't too good anymore.

Is it the hi pressure fuel pump you are hearing? If so, that's just the way it is.

Hopefully someone will come along that can be more helpful -

[blsfrs]

Do you know what your oil pressure is running?

[terboboost]

That sounds like maybe a small exhaust leak.

[Krunsy]

Originally Posted by blsfrs

Do you know what your oil pressure is running?

No, haven't checked, although to be fair if it were low, I wouldn't drive this far, at least I hope so? Seems like the sound is coming from the fuel pump area, but can't tell exactly what it is.

[Ultramaroon]

It could be a bent valve. Has that valve/camshaft cadence. Fuel pump has three lobes per camshaft revolution. You can hear normal hpfp cadence underneath the loud tap.

[Krunsy]

Originally Posted by Ultramaroon

It could be a bent valve. Has that valve/camshaft cadence. Fuel pump has three lobes per camshaft revolution. You can hear normal hpfp cadence underneath the loud tap.

Strange because car drives like a dream, any idea on costs to fix?

[Ultramaroon]

Originally Posted by Krunsy

Strange because car drives like a dream, any idea on costs to fix?

Could be a phasor flopping around in one of the cam sprockets. Maybe it's a failed tensioner. Speculating over cost to fix is waaay down the road.

1. Something's wrong for sure.
2. Sounds like valve or cam

Needs hands of a trustworthy pro to do a couple tests to figure out where to focus. That's your next step. Let us know how it goes.

[Tokay444]

I see the problem.
Wrong oil filter.