Rattle When Pressing The Accelerator

250GTCalifornia

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I've got a weird problem. So here goes:

This rattling noise is produced by pushing the accelerator in my 2017 Si. It will make the rattle when I'm driving in gear or while I'm pushing the accelerator parked in neutral.

Lightly pushing the accelerator about (2-5%) causes this noise, but only if the RPMs are idle while in neutral. It does it all the time when I'm driving.

When the RPM needle goes above 2000 RPM it makes the noise. When the needle falls below 2000 RPM it makes the noise again. It really seems RPM dependent.

Here are the times when I hear the rattle. The only thing installed is a Mishimoto catch can and PRL SRI. The noise SEEMS like it's coming from the driver's side, but it could be the center area. It is definitely behind the dash. I noticed the rattle is louder when the engine is warm and also happens louder on lower gears than higher gears. If I push the accelerator to 15% - 30% to take off, I don't hear it nor do I hear it while coasting.

Lightly pushing the accelerator:
00:06
00:16
00:21
00:24
00:37

Pushing the accelerator 0% to 30% in neutral repeatedly:
00:29 - 00:33

Raising RPM to 2000 RPM then letting it fall below 2000 RPM:
00:48 - 00:50
00:51 - 00:53




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Rickmeister 48

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I've got a weird problem. So here goes:

This rattling noise is produced by pushing the accelerator in my 2017 Si. It will make the rattle when I'm driving in gear or while I'm pushing the accelerator parked in neutral.

Lightly pushing the accelerator about (2-5%) causes this noise, but only if the RPMs are idle while in neutral. It does it all the time when I'm driving.

When the RPM needle goes above 2000 RPM it makes the noise. When the needle falls below 2000 RPM it makes the noise again. It really seems RPM dependent.

Here are the times when I hear the rattle. The only thing installed is a Mishimoto catch can and PRL SRI. The noise SEEMS like it's coming from the driver's side, but it could be the center area. It is definitely behind the dash. I noticed the rattle is louder when the engine is warm and also happens louder on lower gears than higher gears. If I push the accelerator to 15% - 30% to take off, I don't hear it nor do I hear it while coasting.

Lightly pushing the accelerator:
00:06
00:16
00:21
00:24
00:37

Pushing the accelerator 0% to 30% in neutral repeatedly:
00:29 - 00:33

Raising RPM to 2000 RPM then letting it fall below 2000 RPM:
00:48 - 00:50
00:51 - 00:53

Someone else just posted the exact issue you have,and it was what I told them,the rubber o ring on the baffle plate on my Mishimoto catch can flattened out and the baffle plate was flopping on that piece its attached to,plus that piece was loose. Soon as I replaced the o ring and tightend it all up, the noise went away.
Not saying that's definately your issue, but worth it to look and see.
 

Rickmeister 48

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I guess I'll try and put the stock hose back on and see if the noise goes away.
You'll be able to feel that baffle plate flopping around if you unscrew the can,I've had several problems with that mishimoto catch can, had to replace the plastic fittings,the hoses three times,and then this little rubber piece that was causing all kinds of noise,lol
 
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250GTCalifornia

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You'll be able to feel that baffle plate flopping around if you unscrew the can,I've had several problems with that mishimoto catch can, had to replace the plastic fittings,the hoses three times,and then this little rubber piece that was causing all kinds of noise,lol
Thanks for the tip. The thing is... I try and shake the can, but I don't hear a rattle. I'm still waiting for warmer weather to replace the hose back to OEM. Do you think it could still be the can?
 

l15b7allturbo

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Thanks for the tip. The thing is... I try and shake the can, but I don't hear a rattle. I'm still waiting for warmer weather to replace the hose back to OEM. Do you think it could still be the can?
My car is exactly the same. I posted about it a week ago or so. Its definitely the catch can
 
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250GTCalifornia

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My car is exactly the same. I posted about it a week ago or so. Its definitely the catch can
Did you can make noise when you shook it?

I read about your problem. Your heat shield was loose too, right? I might need to get a stick and see if I can poke that shield to see if it has some play, but you're positive it's the can? I just want to get rid of this god damn noise. It's literally piercing through my every thought. Driving through second gear is the worst.
 

Rickmeister 48

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Thanks for the tip. The thing is... I try and shake the can, but I don't hear a rattle. I'm still waiting for warmer weather to replace the hose back to OEM. Do you think it could still be the can?
Well, if your shaking the can while its bolted to the car, you probably wouldn't notice it,now if you have the whole thing off the car,you probably should hear it. I know the cold weather sucks, but its literally about 20 seconds to disconnect the hoses and put the original back on if you wanted to go that way, or you can unscrew the can, then carefully unscrew the long square piece that the baffle plate is hooked to to look at that little o ring. I have OCD and I had to fix that noise asap and luckily that was the issue, hopefully yours is the same since its such a simple fix. The only issue was that I had to wait on the o ring from Mishimoto as it is a warranty thing with them.
 

l15b7allturbo

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Did you can make noise when you shook it?

I read about your problem. Your heat shield was loose too, right? I might need to get a stick and see if I can poke that shield to see if it has some play, but you're positive it's the can? I just want to get rid of this god damn noise. It's literally piercing through my every thought. Driving through second gear is the worst.
My shield was bent due to the incompetent mechanic i took it to originally for my clutch.
I have not fixed anything yet. I don't have a lift to get under the vehicle. I have contacted Mishimoto for replacement. Hopefully by this week I can confirm 100% that it is the baffle plate.

The noise is also making my knock count go up. If i do exactly what you did in the video, my count goes up 1-2. If I drive the car without trying to do what you did in the video, I'll stay at 0.

The knock sensor is picking up the rattle as a knock yet my knock control is stable at 0.49
 

Rickmeister 48

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I'm not sure how much you got into checking out the catch can before you put it on,but you can see in this pic that there are two threaded holes,one is for the brass filter on there and the other is that long square piece with the baffle plate at the end, so it could be any of those loose ad well and just tightening them may fix your issue,if its the o ring,you would have to get a new one.
I'm not gonna say I'm positive its the can, but I had the issue and a few others also.
IMG_20180310_133931.jpg
 
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250GTCalifornia

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So I bite the bullet and removed the catch can and this is what I found:

File_000.jpeg
That silver circular plate with holes? I'm able to jiggle it around. I can rotate it 360 degrees. I thought maybe if I rotated it clockwise it would tighten, but it wasn't. It was just rotating and jiggling sometimes. The straight silver piece that is attached to the lid and the silver circular plate with holes seems solid. It won't jiggle around. Only that plate with holes, but I don't know if that plate could make the same sounds as I was hearing in the cabin.

File_001.jpeg
on another note... I noticed some red thing in my catch can. I know the can was clean before I installed it. Most of the contents were water, but this red liquid was still there. Any idea what it could be?
 

l15b7allturbo

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It's the plate with the holes thats rattling around

That blowby color is really weird. Mine is oil that smells like gas.
 

Rickmeister 48

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It's the plate with the holes thats rattling around

That blowby color is really weird. Mine is oil that smells like gas.
I get some brownish looking stuff in mine, but never red like that. I'm not totally sure but I think Honda coolant is blue, so I don't think that is coolant. Take a look at the other side of that disc with the holes(the baffle plate) and you should see the little black o ring,that's what keeps it from being loose,mine was all crushed and flat and out of the groove,and that was letting the plate move around. On the other side,there should be a little c clip,make sure that is on good also.
 
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250GTCalifornia

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So, I put the OEM hose back on. Took it for a spin and I couldn't hear the noise. I guess I'll have to contact Mishimoto for a replacement.. Now on to the red liquid in my catch can... I'll have to go to the dealership for that. Hopefully it is nothing serious.

Thanks a lot @Rickmeister 48 and @francomakou for your help! You guys are the pillars of this community.
 

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