FL5: Odd noise with front Resonator deleted and valve open.

[naafl5]

This is a repost from a reddit thread in r/Civic_Type_R where I didn't get much traction. Hoping maybe I'll get some answers here.


I pulled the trigger on the front resonator delete. I figured I didn't have much to lose if I was gonna put a new exhaust on it if I didn't like it.

I also pulled the valve fuse so that it is always open.

Intermittently I hear what I can only describe as a distant base drum or a stifled cough (one cough with mouth closed) coming from the exhaust. Happens at idle sometimes, also happens when off the throttle but in gear.

Any ideas what it could be?

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[jtlctr]

I have the same sound. I also did the resonator delete over the weekend, but that bass hit has always happened. To me it sounds like a thump from the subwoofer, but I don’t know if that’s it. I may try disconnecting the sub and see what happens.

 

[naafl5]

I have the same sound. I also did the resonator delete over the weekend, but that bass hit has always happened. To me it sounds like a thump from the subwoofer, but I don’t know if that’s it. I may try disconnecting the sub and see what happens.

Ok, glad I'm not alone. I doubt it's the subwoofer given that my audio is off when I hear it.
Is your valve fuse pulled too? I may try putting the fuse back in to see if that has anything to do with it.

 

[jtlctr]

I had pulled the fuse, but it’s back in now. The thump happens under both scenarios. I mainly keep the engine setting in +R. I will try it in comfort and see if it happens then.

 

[Starchland]

If always at a specific rpm, then you have described resonanace

 

[naafl5]

I had pulled the fuse, but it’s back in now. The thump happens under both scenarios. I mainly keep the engine setting in +R. I will try it in comfort and see if it happens then.

I have noticed it happening in comfort as well.

 

[naafl5]

If always at a specific rpm, then you have described resonance

It varies, common at 3k in 3rd gear but can happen while idling out of gear as well.

 

[SaberX]

I've heard it too, kinda like a weird sound 'thump' every once in a while. I hear it more when the valve is locked open and I have the windows down. I think it's just a quirk of how the car is tuned from the factory.

 

[naafl5]

I've heard it too, kinda like a weird sound 'thump' every once in a while. I hear it more when the valve is locked open and I have the windows down. I think it's just a quirk of how the car is tuned from the factory.

Yes, exactly! Okay so I didn't "break" anything...cool.

 

[jtlctr]

I also barely notice it with the valve closed. With the valve open, I can get it to happen every time letting off throttle and getting back on around 3k rpm in 3rd gear.

I’ll consider it my burble tune.

 

[neptune]

Put the fuse back in see if that makes the noise go away

 

[ThunderPigeon]

I was just hearing that sound myself. Picked up my FL5 today and I just hit 100 miles. No modifications. I was hearing it in +R mode, hadn't tested any other modes. I was thinking it might be related to the pumped in engine noises. Just came on here to see if anyone else has the issue.

 

[TypeRD]

I also barely notice it with the valve closed. With the valve open, I can get it to happen every time letting off throttle and getting back on around 3k rpm in 3rd gear.

I’ll consider it my burble tune.

What you guys are describing sounds almost like it could be a back pressure “thump.” Might be helpful to post a sound clip if you can.

Thinking about this more : The ITS doesn’t have the front resonator and the ECU is tuned to make more sounds (pops, bangs, burbles). I bet there’s back pressure “thumps” in the mix too, but they’re not obvious because those thumps are in concert with other nice exhaust sounds. In the FL5, with the resonator deleted, we only have a standing bass, but no other instruments in the orchestra (because the ECU hasn’t been programmed to add them).?

I’m not saying this is the answer, but it seems very logical.

 

[jtlctr]

What you guys are describing sounds almost like it could be a back pressure “thump.” Might be helpful to post a sound clip if you can.

Thinking about this more : The ITS doesn’t have the front resonator and the ECU is tuned to make more sounds (pops, bangs, burbles). I bet there’s bank pressure “thumps” in the mix too, but they’re not obvious because those thumps are in concert with other nice exhaust sounds. In the FL5, with the resonator deleted, we only have a standing bass, but no other instruments in the orchestra (because the ECU hasn’t been programmed to add them).?

I’m not saying this is the answer, but it seems very logical.

I'm sure you're right. I wonder if a bit of sound deadening in the hatch area might help.

 

[TypeRD]

I'm sure you're right. I wonder if a bit of sound deadening in the hatch area might help.

It may be worth a try, but unless you add sound deadening along the full length of the floor (because the sound is likely resonating and traveling throughout the exhaust pipe and into the cabin), I don’t think it’s going to help much. That’s just my opinion. Maybe others with more experience will chime in.

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