Strange idle/acceleration noise

[ChefRyeSi]

Very pronounced noise as shown in the video especially when warmed up. Any idea what’s wrong? This cant be normal.

 

[arpypat]

Very pronounced noise as shown in the video especially when warmed up. Any idea what’s wrong? This cant be normal.

Sounds like something is rattling in there.

Do you have an aftermarket intake? I had a similar noise/vibration due to a broken isolation mount on my 27won intake. Wondering if you may have broke one off too?

Do you have any upgraded motor mounts at all?

Any other engine mods?

 

[ChefRyeSi]

Sounds like something is rattling in there.

Do you have an aftermarket intake? I had a similar noise/vibration due to a broken isolation mount on my 27won intake. Wondering if you may have broke one off too?

Do you have any upgraded motor mounts at all?

Any other engine mods?

I have a PRL cobra race MAF intake and obviously then KTuner but that’s it. What are things I can look at or do I need a mechanics help. It sounds like it’s coming from the right passenger side of the engine bay as well.

 

[ChefRyeSi]

Sounds like something is rattling in there.

Do you have an aftermarket intake? I had a similar noise/vibration due to a broken isolation mount on my 27won intake. Wondering if you may have broke one off too?

Do you have any upgraded motor mounts at all?

Any other engine mods?

Also, why would it only occur after warming up if somethings stuck in there?

 

[arpypat]

I don't think something is stuck. The opposite - I think something that's supposed to be bolted down has come loose.

Did you check to see if your intake is vibrating?

You should have someone rev the car a bit while you look in the engine bay.

 

[ChefRyeSi]

I don't think something is stuck. The opposite - I think something that's supposed to be bolted down has come loose.

Did you check to see if your intake is vibrating?

You should have someone rev the car a bit while you look in the engine bay.

ok so lets say something is loose (i think the same thing) whats with the accel noise?

 

[Masked]

ok so lets say something is loose (i think the same thing) whats with the accel noise?

Well if something is loose and you tap on the gas pedal, the engine will create more vibration as the rpm goes up so the loose thing might also vibrate more

 

[ChefRyeSi]

Well if something is loose and you tap on the gas pedal, the engine will create more vibration as the rpm goes up so the loose thing might also vibrate more

I read that the Misihimoto catch can rattles for people, which i have, and its some bronze fitting inside it. I'll have to look at it, but still not sure of the almost grinding noise when accelerating. Myabe its linked but i dont think so as they just sound different

 

[fabrizzio71]

It could be your timing chain tensioner. I would rule that out first as if that fails fully no more engine. Here is an example of what that sounds like:

 

[ChefRyeSi]

It could be your timing chain tensioner. I would rule that out first as if that fails fully no more engine. Here is an example of what that sounds like:

Hey, thanks for the video. The warm idle does sound closer to my noise but like in my video, less consistent and more sporadic. And by no more engine you mean if the tensioner went out, the engine just wouldn’t turn over?

 

[ChefRyeSi]

Update: checked the catch can, everything seems fine. Tensioner, I can’t take apart the engine to really look at that right now so I’m not sure

 

[JT Si]

Update: checked the catch can, everything seems fine. Tensioner, I can’t take apart the engine to really look at that right now so I’m not sure

There's an inspection window on the side of the engine beside the accessory belt pulley on the crankshaft.

There's a whole factory service manual procedure for removing the cover, inspecting the tensioner, and replacing the cover. It's a bit of a pain because it's sealed with 2 bolts and honda bond, but the scope of the job is very small relative to actually taking the valve cover off and trying to inspect the chain itself.

It also is a common oil leak point.

 

[ChefRyeSi]

There's an inspection window on the side of the engine beside the accessory belt pulley on the crankshaft.

There's a whole factory service manual procedure for removing the cover, inspecting the tensioner, and replacing the cover. It's a bit of a pain because it's sealed with 2 bolts and honda bond, but the scope of the job is very small relative to actually taking the valve cover off and trying to inspect the chain itself.

It also is a common oil leak point.

Now do you think, if it is what’s causing the noise, that it’s a must fix? I’m not seeing any performance loss or gas mileage either. So nothing is happening. Just the noises. Should I fix it or just let it be?

 

[fabrizzio71]

Hey, thanks for the video. The warm idle does sound closer to my noise but like in my video, less consistent and more sporadic. And by no more engine you mean if the tensioner went out, the engine just wouldn’t turn over?

You're welcome. I'm not sure exactly what would happen if it failed completely, the chain could skip and then timing would be off which is of course never good. But I suspect the noise would get worse and more consistent rattling would occur before anything serious happened. How many miles are on the car? I did see recently a youtuber with a modified 10th gen si who replaced his chain tensioner (he had blown his engine but not due to that). There is an example of the noise at like 3 minutes in this video.



Let us know if you end up diagnosing it definitively.

 

[ChefRyeSi]

You're welcome. I'm not sure exactly what would happen if it failed completely, the chain could skip and then timing would be off which is of course never good. But I suspect the noise would get worse and more consistent rattling would occur before anything serious happened. How many miles are on the car? I did see recently a youtuber with a modified 10th gen si who replaced his chain tensioner (he had blown his engine but not due to that). There is an example of the noise at like 3 minutes in this video.



Let us know if you end up diagnosing it definitively.

Replying for a final update. Honda had the car for two days, heard and found the noise. SO, i should've looked in the forums but regardless, it was my catch can making the rattles. From what i've read, the PCV system always makes these rattles and such but is dampened by the stock hoses but when the catch can system is introduced it opens this up slightly more in terms of flow and the hoses provided by Mishimoto arent amazing. As well, the can is mounted to the firewall and any NVH created by the PCV which was once dampened is now amplified by the can and is what i have been hearing. Many other if not all users have had this noise happen

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