Coyote Gen3 cold start engine sound analysis (Mach 1)

[murick]

I hope someone could help me with understanding the different sounds I am hearing when listening to the cold start of my Mach 1.

EDIT: Just a note to avoid confusion - this is about the engine sound not the exhaust sound.

I am including the recording and the infographics below, and just for the record repeating it here:
1) From the start until 0:30 there is a "rattle" I called "cockchafer" as it reminds me mostly a flying cockchafer.
2) 0:34-1:57 there is another sound which is different from any other sound in that it is random - like a corn popping on a pan but with a metallic vibe
3) 0:50-2:18 something similar to the earlier cockchafer but with lower frequency - the closer analogy would be a playing card flapping on the wheel spokes of a bike (kids play), this one slows down at 2:00 and completely disappears at 2:18
4) 1:45-end soft high pitch buzz, kind of difficult to hear, but the ramp up at the beginning is audible (when focused on the sound).
5) From 2:18 I believe, apart from 4), there are only valves.

Few notes:

• I recorded several cold starts and they are all similar with timing and sound characteristics. Any other start on hot or partially hot engine gives a different sound with some sound shortened or even missing. Simple restart can go directly to the final stage.
• The video is recorded playback visualization from Audacity program, the times are related to the times in program not to the times of the video (which starts 1 second earlier).
• There are two tracks (phone has two mikes) but the imaging is poor.
• Each track shows an amplitude envelope and a spectrogram. The latter gives some clue about the sound character change as well.
• I can hear all sounds distinctly on my headphones, but the resolution might be poor on speakers, so please try using headphones if you can.
• I recorded it with my phone standing on the front bezel (using flip cover to raise it up) of the engine bay with the hood open, using folded towel as an insulation from vibration.
• The most suspicious is a popping corn sound, because it is random and seems to be coming mostly from the passenger side.

EDIT: Adding audio only track in case the video does not play

Original video:

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[The Demon]

The video doesn’t play for me. I’d love to hear what it sounds like so I can compare it when I start mine tomorrow. Miine sounds fantastic when I start it so I’d like to see what your sounds like.

 

[Cux211]

Yep won’t play

 

[murick]

@The Demon @Cux211
Please try again - I have uploaded reencoded version of the video and also added audio only version as a fallback.

 

[Cux211]

The only thing I can hear for sure is that popping/rattling noise no idea what the hell that is but I’d be concerned and take it in if it was mine

 

[The Demon]

When I start mine I smile and then I get in and go. What made you stand out there and listen to it for that long?

 

[murick]

When I start mine I smile and then I get in and go. What made you stand out there and listen to it for that long?

First, let me point out that the sounds I recorded I do not hear normally when I am in the car starting it. One has to move outside and pop the hood to get the full orchestra. The cabin soundproofs it quite well.

The sound I hear regularly (https://www.mustang6g.com/forums/threads/short-screeching-sound-right-after-the-engine-start.182305/) is, on the other hand, not captured in the recording, because it is probably not coming from the engine or the engine bay.

Second, I definitely do not start my car by going out popping the hood and listening for 3 minutes to the engine . The way I got to it, was that once when leaving the underground parking lot in our apart. building I had to get out of the car to check the doors or something and heard some strange sound transition of the freshly started cold engine. I do not remember which one, whether it was end of 1), or start of 3) but I was curious. Plus the concrete narrow interior of the leaving passage made it meaner.

Later when I was parking outside and doing some cleaning, checking the oil, etc. with the hood open I thought I might actually give it a try and listen to the engine start just out of curiosity. There was a guy chilling in his truck nearby who got curious when I popped the hood and wanted to hear the engine too! So I started it and we listened and after that the guy told me that he did not like the way the passenger side sounded, but he was not able to articulate it better than just that.

Since then when I had the opportunity to record it I did and at the same time was trying to locate or understand the different sounds origins. Apparently it is a long story .

The only thing I can hear for sure is that popping/rattling noise no idea what the hell that is but I’d be concerned and take it in if it was mine

I guess it could be difficult to describe or identify the individual different sounds just from the recording. The description I gave is my best effort considering my limited vocabulary and the fact I also heard the sounds live. The idea was that it could help someone who might have heard something similar (in the real life on his/her engine).

What I believe should be however clear even in the recording are the different transitions:
0:30 first "rattle" stops
0:34 random popping starts
0:50 the second rattle starts
2:18 the second rattle stops

When the random popping stops is not very obvious and lost in the second rattle, my mark 1:57 is my best guess after some listening. It is the one which concerns me though.

 

[2021 Mach 1]

For comparison, the first cold start is fully stock:

 

[murick]

For comparison, the first cold start is fully stock:

I do not think we can really compare the exhaust sound to the engine sound. What I recorded is the engine sound as heard when listening to the engine (with open hood).

 

[Tucker80]

Engines make all kinds of noises. I think you're over thinking this. Drive it and move on. If the engine noise continues to bother you, you probably bought the wrong car. If something does turn out to be wrong in the future that's what warranties are for, but honestly I think you're just paranoid.

 

[Cux211]

You’re going way to nuts over this, that popcorn sound would be the only thing I’d be concerned about, I’d just take it in and let the dealer check it

 

[2021 Mach 1]

I do not think we can really compare the exhaust sound to the engine sound. What I recorded is the engine sound as heard when listening to the engine (with open hood).

Apologies, I'm sorry.

 

[Hack]

Engines make all kinds of noises. I think you're over thinking this. Drive it and move on. If the engine noise continues to bother you, you probably bought the wrong car. If something does turn out to be wrong in the future that's what warranties are for, but honestly I think you're just paranoid.

I agree with this. If something is really wrong, the engine will set a code and then you can take the car in to get the issue fixed. Engines make noises. Especially engines with long timing chains, variable camshaft timing, high-pressure direct injection plus port injection, IMRC valves, etc, etc.

The bottom line for me, if I hear a noise from an engine in a relatively new car, I assume that's a noise that the engine is supposed to make. Unless there is a leak or a check engine light, I doubt that anything is wrong. Yes of course if there's a knocking noise like a loose rod, that's different, but there are just a lot of mechanical noises that naturally occur in an internal combustion engine with lots of complex add-ons for emissions, etc.

 

[5doorsoffury]

cockchafer sounds like a phallic themed limo driver

 

[PoCoBob]

I agree with this. If something is really wrong, the engine will set a code and then you can take the car in to get the issue fixed. Engines make noises. Especially engines with long timing chains, variable camshaft timing, high-pressure direct injection plus port injection, IMRC valves, etc, etc.

The bottom line for me, if I hear a noise from an engine in a relatively new car, I assume that's a noise that the engine is supposed to make. Unless there is a leak or a check engine light, I doubt that anything is wrong. Yes of course if there's a knocking noise like a loose rod, that's different, but there are just a lot of mechanical noises that naturally occur in an internal combustion engine with lots of complex add-ons for emissions, etc.

I completely agree with this. These engines are loud and make noises that pushrod V8's never made. Add in that the Mach 1's don't get the engine cover that the GT's get is just going to make it seem louder.

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