perlandas

Blew my AP1 engine last summer due to oil starvation.
During the winter it was given a low milage F22 engine that has been fully rebuilt, only OEM parts. It was tuned with Doctronic ProECU-S2K and did 233 HP at 8000 RPM on the dyno.

Picked up the car about a month ago and started breaking the engine in with instructions from the tuner before the first oil change was to be made. I can't remember exactly when,
but after a while, I started to feel a slight vibration through the gas/clutch pedal upon clutch release and low rpm, 2000 ~ ish. Didn't think too much of it,
I thought it was just the brand new OEM clutch being broken in.

Now that I was aware of the vibration/(slight rattle knock) I started to hear it when I drove the car with the top down, previously I had only felt it. It's more present from inside the cabin.
I continued driving the car and eventually did the oil/filter change.
Since then I have done a lot of driving every day and put a decent amount of miles on the new engine, enjoying the car.

Being hyperaware of the issue I couldn't let it go. It has not gotten worse or better, it's stayed the same so I contacted the tuner who also built the engine and showed him the
sound and he agreed that there's definitely a slight knock at a certain RPM that gets noticeably more audible
as the clutch gets pressed and is also notified by the knock sensor.

He proceeded to fiddle with the ignition at that rpm range to see if the knock went away, and it did (can't remember exactly what he did with the tune I'm no expert) but he said it's not the tune itself causing it though.
He then removed the oil pan and checked the bearings.
Everything looked brand new and there were zero metal shavings in the oil. Oil pressure was also really good and had no issues.
He determined that the sound was coming from the engine block but was not 100% sure, it was really hard to pinpoint.

We didn't have much time left that day so he put the engine back together and then we put some really thick oil together with the regular oil to see if the issue persisted.
During startup, the noise was pretty much gone and the engine felt great through the pedals with no sound but it came back of course as soon as the engine was at operating temperature.

Here's video showing the sound:
https://www.dropbox.com/s/xo78civu5i..._4604.MOV?dl=0
https://www.dropbox.com/s/jpa237leva..._4607.MOV?dl=0


I still have no idea what it could be. I have found threads with a similar issue but they were all dead ends.
https://www.s2ki.com/forums/uk-irela...knock-1144957/ etc.

Any help is appreciated. I'm thinking that if it isn't the engine, then maybe the engine is causing something to rattle just at that rpm. Might be clutch/transmission related, but it happens in neutral as well.

zze86

Sounds like maybe the thrust bearings are worn or out of spec...? Or maybe you have an upgraded clutch/pressure plate? See this thread for a good visual how-to to check crank movement.

perlandas

Maybe? I'll check that thread out. Thanks

Car Analogy

Piston slap maybe?

Were the pistons replaced? If not, if someone cleaned tops of piston with a wire brush, like there was heavy carbon, etc, it can create a rough surface on aluminum face, and the peaks run hotter and can cause pre-ignition.

That would explain how it could be engine, not the tune, yet how an adjustment to the tune could still help.

flanders

What kind of clutch does it got?
If you rev it like in the videos without pressing down clutch pedal can you still hear the weird sound?

perlandas

Yeah, the Pistons were replaced with oversized ones. It might be piston slap, but it would cost a lot just to find out.
It has an OEM clutch. I'm not sure if there's a difference between the AP1/AP2 clutch but I assume they're the same. I drove it earlier today and the sound is still there without clutching.
But it's most present during take off for example or reversing out of a parking spot when the clutch and gas pedal meet each other, then I can really feel the whole engine revolving through the pedals.

My first ever trackday is on the 25th. Would suck if I had to cancel due to this. Wouldn't want to blow another engine up though.
Who knows it might just be fine, but I would really like to get it sorted out. Especially after spending so much money on the swap.

Jstuning_

Sad to hear, hope its something Easyfixed.
if it gets worse when clutching it probably can be the thrust bearings/play, for me it sounded most at 2000rpm but you still can hear the backround knocking up to 4000rpm it just sounds a bit different.
when you press the clutch you put load on the axial bearings, if it was something with throwoutbearing,fork or gearbox it usually rattles more when clutched not pressed down.
are the gearbox the same as before rebuild?
than you can rule that out,

it can be pistonslam but that usually gets less noisy when engine gets warm,
if It’s a serious engine builder than you can ask for the clearance specs like piston to wall and axial play, if all that was checked than it can’t be pistonslam or ”crankwalk”
the more you can rule out the better.
than it maybe can be something like timing chain atleast or valvelash.

Also pull the sparkplugs and check them for metall, check the piston top. But its very unlike to knock at no load.

Was the engine breaked in before the dynotuning?

starchland

He took the engine apart and checked what?
cut open the old filter and check VTEC screen

Chuck S

Hopefully this is merely clutch related and we're not seeing yet another demonstration of the non-rebuildability (if that's a word) of these engines. The success rate seems dismal.

-- Chuck

perlandas

Yeah, it's the same gearbox. I can ask him about the specs, we also talked about piston slam and crank walk but he thought it would be unlikely to be the issue.
The sound is not coming from the timing chain and the videos I have seen of that type of issue do not sound the same. Would not hurt to check it though. The next step would probably be checking the head. I'm not sure if the engine was broken in before the dyno, don't think so.

@starchland he looked at the bearings and felt if everything was alright. I haven't cut open the filter or checked the VTEC screen, should probably do that as well.