Si Has anyone here heard a light knocking noise during fast idle in the cold?????

[PowerPerLiter]

Let me start off by saying I am a service adviser by trade and a certified adviser for Honda at the dealership level for 2+ years (been advising for almost a decade for 5 manufacturers).

I know what vtc rattle is and sounds like. This is not that.

It has been happening since brand new (7 miles) and is so light most of the time I question how many "normal" drivers would notice this.

It is not rhythmic and sounds like a knock not a tick and seems to be under valve cover toward passenger side of engine compartment.

Cam chain barely contacting valve cover was another possibility.

Almost sounds light piston slap but Im not so sure.

High pressure fuel pump relief possibly?

Seems like a sound the square cam lobe that operates the pump could make if the pump actuator arm was "bouncing a little" off the cam lobe.

Can I get any input on if anyone else has experienced this?

It hasn't changed or gotten worse and I am changing oil every 5 k miles religiously with the real full synthetic Honda 0w-20. With honda filter.

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[PowerPerLiter]

maybe the dual mass flywheel??

 

[dallasjhawk]

a video with the sound would help a lot

 

[PowerPerLiter]

I would post one but i dont think its going to pick it up. Its that faint. But in person and listening for it its definitely noticeable. Ill see what I can do.

At this point I am just seeing what possible options there are to be creating this and brain storm it.

I have read our engines go into stratified injection during warm up which is a lean burn condition until the cats warm up.
I also know that the timing is advanced by up to 6 degrees during warm up. Could this also have anything to do with it?....
I would try without the timing added but I know its there for stable combustion so im hesitant to do so.
If I lived in the south still instead of Ohio I wouldnt even be posting this thread or worried about it but knowing what kind of winter Im about to subject the car to for the first time has me a little more curious about it.

All this being said this faint noise is the LITERAL ONLY THING that makes me hesitant about buying the car at the end of my lease.
hmmm.........

 

[PowerPerLiter]

Just to add clarity to the thread I just learned the Si is non-dual mass (allegedly) with a different part number and much cheaper pricing.

So that checks that off the list.

At this point im leaning toward very very light piston slap which is entirely plausible. The noise just seems more erratic than what ive seen with other cars. Maybe this is because its so minimal...

 

[davemarco]

It is dual mass, unfortunately

 

[PowerPerLiter]

It is dual mass, unfortunately

Gotcha thanks for the info. Well that puts it back in ring of possible sources. could be the dual mass making a little noise during cold startup. Hmmm

 

[PowerPerLiter]

Imagine a little guy under the plastic valve cover reaching up with a rubber mallet and hitting the underside of the valve cover randomly / sporadically.

 

[dallasjhawk]

Gotcha thanks for the info. Well that puts it back in ring of possible sources. could be the dual mass making a little noise during cold startup. Hmmm

are you registering any knock or movement in your kcontrol on start up and warm up? or during driving

 

[PowerPerLiter]

Not at all. Occasional 1 count on cylinder 3 but has happened twice in time of ownership and nothing during the startup process. Nothing raising my eyebrow.

 

[d1zguy]

thats normal.

When cold valve clearances are off until warm. The L15 does not have hydraulic valve lifters and this is what you hear.

Some cars even have piston slap when cold and goes away when warm. Completely normal.

Even my s2000 engine when cold had a loud top end but super quiet once warmed up. I would worry if it did it when warm and it was sporadic and followed RPM

read this thread

https://www.bimmerforums.com/forum/showthread.php?936143-Cold-motor-forged-piston-quot-slap-quot

and from personal experience my 1987 325e m20b27 had loud lifters and piston slap when cold but smooth once warm and did not eat an ounce of oil. Intake and combustion chamber were squeaky clean.

put over 60k in 5 years and sold strong as ever.

look up any ferrari FXX engine sound when cold and it sounds like it's falling apart. completely normal noise when cold. engines are not made to be run dead cold



If you were to painstainkenly use a block heater/oil heater before any cold start up you could got 500k miles or more on same internals.

 

[Si Is Life]

So this is a old thread this was the sound im looking for too the sound is so light that it cant be heard on vid but on person u can clearly hear it i have this issue too with my 2020 si 7k miles its coming from under the valve cover at passenger side

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