High knock count at part throttle after cam install

FlashPro questions & answers specific to the FN2 European Civic Type R
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Jesper
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Joined: Wed Aug 17, 2016 11:38 am

High knock count at part throttle after cam install

Post by Jesper » Sat Oct 28, 2017 9:50 am

Hi Guys

Car is also running Skunk2 CAI, RRC intake manifold, 2.75" catback, modified circuit sport exhaust manifold, and it is from that setup the map originates.

I have just installed: Toda A3 cams, Toda valve spring, Toda timing chain tensioner and new Honda chain.

I have tried to make knock free base program, but cannot get the knock low, no matter how much ignition I remove.
I have huge knock count on low cam, mainly between 2200 and 3500 RPM and 30% Throttle colum 5-8.
There where 0 knock before cam install, except the occasionally 1 or 2 at max load and high RPM.
After 30 minutes I can now easily have >300 counts.
It is mainly on cylinder 2 and 4.
I also get knock if I limit VTC to 0 degree, but it seems to be less than on 10 and 20.

I have just readjusted valve lash after 300 km. It did not change the knock count.
I have also tried removing 5 and even 10 degree timing on 0, 10 and 20 degree VTC tables in the affected arear.
But it changed nothing except a bit less in column 8-9. I found the affected area using knock sensor overlay.
I cannot hear any vibration or anything abnormal. Valve train seems very quiet.

Question: Is such high knock count common with aftermarked cams? And should I just adjust knock sensitivity?
Or is something wrong?

Attached logs are program without removing ignition.

Best regards
Jesper
Attachments
28-10-17 RRC S2 AFM9 KN5 ZDX41 TM1 A3 -5@HC 20g VTC.fpcal
(20.86 KiB) Downloaded 54 times
28-10-17 RRC S2 AFM9 KN5 ZDX41 TM1 A3 -5@HC 20g VTC.fpdl
(3.14 MiB) Downloaded 54 times

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Hondata
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Re: High knock count at part throttle after cam install

Post by Hondata » Sun Oct 29, 2017 8:12 am

Is such high knock count common with aftermarked cams
Yes, but not for Toda cams as they generally as quiet like stock. The first thing is check how you are measuring valve lash. Some people measure between the rocker and valve stem, which will give excessively large clearances and a lot of noise. The correct way is between the rocker and cam lobe. Also there are difference clearances depending if you set them hot or cold. What are you using?
Hondata

Jesper
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Joined: Wed Aug 17, 2016 11:38 am

Re: High knock count at part throttle after cam install

Post by Jesper » Sat Nov 04, 2017 10:51 am

Hi Hondata

Thank you for the answer.
I measured between between rocker and valve stem.
That is the Honda procedure according to the K20 shopmanual?

I used 0.23mm for intake and 0.26mm for exhaust totally cold. That is what was written on the TODA CAM card?

Best regards
Jesper

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Hondata
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Re: High knock count at part throttle after cam install

Post by Hondata » Mon Nov 06, 2017 11:30 am

Yes, you are correct, my mistake. Between the valve stem and rocker. Clearances sound about right too.
Hondata

Jesper
Posts: 6
Joined: Wed Aug 17, 2016 11:38 am

Re: High knock count at part throttle after cam install

Post by Jesper » Mon Nov 06, 2017 12:12 pm

But is between rocker and cam better?
Or what else could cause the Knock noise?

Best regards¨
Jesper

Arno
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Location: The Netherlands

Re: High knock count at part throttle after cam install

Post by Arno » Mon Nov 13, 2017 5:54 am

TODA A3's on K20A2 here (with matching TODA springs and chain tensioner) too and I have always had varying degrees of knock registered around 2500-3500rpm even at very low throttle openings where it really shouldn't even be able to...

Tried pulling timing until ridiculous low numbers, marginal to no change. Tried running the car on 102RON race fuel for a while (it's ignition mapped to 95RON), no change. Checked valve lash, etc. etc... All in spec.

During an engine rebuild (not related.. debris in an oil line caused a spun rod bearing) I changed from the EU K20A2 pistons and thin TODA head gasket to DC5/K20A PRC pistons and regular K20A head gasket. No change.

There's no pinging noise to be heard, no change in exhaust or intake note. All you do see is a little more noise in the knock sensor pickup datalogs and also the knock threshold dropping around that rpm so it will sometimes just spike over it.

Full throttle running is all clear, no knock all the way to the rev limiter at 8600.

Seems there's just some valvetrain resonance set off around 2500-3500 rpm that the knock sensor picks up and is just in the right frequency range for the ECU to trigger on. Perhaps combined with some scavenging/pulse effect from my 4-2-1 manifold.. Dunno.. Looks a lot like a 'phantom' knock.

For now I just ignore it. Doesn't seem to cause any issues and my sparkplugs look fine and so do the piston and combustion chamber surfaces when examined with a bore-scope. (did 100+k miles on the engine before the rebuild, so it can't be too bad ;) )

Bye, Arno.

typer86
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Re: High knock count at part throttle after cam install

Post by typer86 » Wed Dec 06, 2017 10:56 pm

Check again your valve lash. I had the same random knocks after receiving my car back from the dealer (unable to adjust the valve lash)...
I would try to adjust the TODA cams intake side: 0.22 (+0.01 offset) if you thigh tend the screw up, check again if the valve clearance is the same.

EDIT:
I am 100% sure it is causing by wrong valve lash adjustment. Cyl #1 = OK all other produce to much noise.
Engine does not rattle like a sewing machine? :D In my case the engine noise was so loud - tick ... tick ... tick ....

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