Si Noticing a new noise after bolt ons

[Biff_Inglewood_420_69]

Hey there folks, I have a 2019 Si which I run on a Hondata +6 tune. I recently added a PRL short ram intake and PRL downpipe/frontpipe combo. I started noticing a noise after these, almost sounds like a loose washer spinning around. I've been under 3 times to make sure everything is tight (and to get that OEM ring gasket out between the frontpipe and the rest of the exhaust), everything I touched is properly torqued.

It should also be noted that the car hauls ass and runs perfectly aside from this noise. Builds boost like normal and runs like a champ.

So anyways, this noise does not happen at part throttle, only full throttle. My buddy thinks it could be wastegate noise keeping the boost at target, which would make sense and maybe with the bolt ons it's just more noticable.

I freaked out to the point of buying and mounting a GoPro in the engine bay since my phone couldn't pick it up. It is only audible from the driver's seat, passenger can't hear it, so wastegate would make sense again since it's the correct side.

Video (noise starts around 7 seconds in and only lasts a second or two):

Is this just normal noise or do I need to have this looked at?

Side story that I worry could be related but I'm sure it's not, first time I got the DP/FP tightened up, I fired it up to check for leaks... but in my excitement I forgot to put the intake back on... and forgot to take the washcloth out of the end of the TIP. So I took that pipe off and fished the washcloth out, it was still caught in the bend and was a few inches from the compressor inlet, but holy shit I was freaking out...

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[Biff_Inglewood_420_69]

Here's a datalog that seems to support the wastegate theory. I've never heard the noise before, but maybe I'm just sensitive because of the mods I did. Also maybe the mods made it more audible. Also, this is my first turbo car.

 

[choo]

I cant hear anything abnormal with headphones on at max volume +10 decibels in the EQ...

could you describe the noise or when it happens better?

Cool to see a camera there during a pull btw

 

[Biff_Inglewood_420_69]

Yeah, it's very difficult to hear unless you've been driving yourself insane obsessing over it for weeks. It starts at the 7 second mark in the video and is over at the gear change two seconds later. It's like a loose washer sound or metal on metal pivot sound, in a pulsing rythym and very quiet compared to the rest of the noises going on. I'll try to get a video from outside without wind noise drowning it out. It's easier to separate from engine noise in the driver seat with all the engine bay insulation.

Glad you liked the shot, it is a pretty cool view!

 

[slayerx02]

Yup, very subtle but I'm familiar with that sound from the best/worst car I've owned, a 2011 mini cooper S lol, not gonna say it absolutely is the flapper valve in your case but its highly probable considering when the sound presents it self during your pull, when the waste gate would be open to regulate boost pressure.

 

[Biff_Inglewood_420_69]

Yup, very subtle but I'm familiar with that sound from the best/worst car I've owned, a 2011 mini cooper S lol, not gonna say it absolutely is the flapper valve in your case but its highly probable considering when the sound presents it self during your pull, when the waste gate would be open to regulate boost pressure.

Thank you thank you thank you. It's been freaking me out a little bit and I was 90% sure it wasn't an issue but I really needed someone to (1) actually hear what I was talking about and (2) tell me it's normal. Much appreciated!

 

[choo]

Ok I think I can hear it now, just sounds like normal turbo sounds to me still though lol.

*edit* just turned off my audio compression and I can hear it now. It sounds to me like to turbo oscillating boost pressure maybe? AKA the wastegate I suppose? Doesnt sound bad at all.

 

[Biff_Inglewood_420_69]

Thanks for giving it another listen! This is my first turbo car and I couldn't hear the noise until after the intake, downpipe, and frontpipe which all went on within days of each other. Car was driving fine, but it sounded a lot like a loose washer and to happen immediately after tinkering, I just needed some confirmation. Thanks again! I think two people saying they hear it and it's fine is enough. Now that I know there's nothing wrong, it's time for motor mount, intercooler, and maybe a clutch...

 

[Rustlinjimmies]

once removing the stock air box and stock exhaust you'll hear noises you never heard before just shows you how much they cage in with all those dampeners to quiet the sound.

 

[Biff_Inglewood_420_69]

Yeah, I was expecting the induction noise and pops from the exhaust, but I don't think I ever heard the wastegate flapper valve when it was stock. Considering the size of the stock downpipe, it's no wonder I never heard it before. It's so hard to hear that I thought I was going insane, especially since my girlfriend couldn't hear it from the passenger side and is too scared to drive my cars (even though she took the Miata for a spin when I was out of town... Something about me watching gets her flustered since she knows how much work I put in on these things)

 

[bbeem]

I have PRL SRI and can get that fluttering air intake sound at a certain RPM/Throttle input. IIRC it happens near WOT when a little low in the RPM like 4k especially in 5th or 6th. I can almost feel it in the throttle a little bit too. No worries.

 

[disgraced.fk8]

I have PRL SRI and can get that fluttering air intake sound at a certain RPM/Throttle input. IIRC it happens near WOT when a little low in the RPM like 4k especially in 5th or 6th. I can almost feel it in the throttle a little bit too. No worries.

I have been looking to see if anyone has the same noise I have - this sounds like it is exactly it. I think it is the car keeping the boost on target from my now hours of research, but it doesn't seem to have any negative effects on the car. It happened only after the intake, but rarely. Now I have an Afe downpipe which opened it up more and it happens a lot. It just builds boost so damn fast now!

I wonder how we can tune this out, because if I lower the boost targets it will likely happen more as the intake is larger. It definitely makes sense too when you think about how much more air moves through something like the PRL or Mishimoto SRI's (that's the one I have) compared to the stock one. I really want to see if I can work with ktuner to try and get rid of this because it doesn't sound that great..... lol.

 

[bbeem]

I have been looking to see if anyone has the same noise I have - this sounds like it is exactly it. I think it is the car keeping the boost on target from my now hours of research, but it doesn't seem to have any negative effects on the car. It happened only after the intake, but rarely. Now I have an Afe downpipe which opened it up more and it happens a lot. It just builds boost so damn fast now!

I wonder how we can tune this out, because if I lower the boost targets it will likely happen more as the intake is larger. It definitely makes sense too when you think about how much more air moves through something like the PRL or Mishimoto SRI's (that's the one I have) compared to the stock one. I really want to see if I can work with ktuner to try and get rid of this because it doesn't sound that great..... lol.

Right. Just go WOT or downshift I figure. I think it's a pumping effect with air pulsing through the intake. I don't think it's a problem at all. I can even feel it a little, like a sipping pulsing noise if you rolled your tounge or lips while making suction.

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