#2 cylinder knock

FlashPro questions & answers specific to the 2006-2011 Americas Civic Si
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BlackSiR
Posts: 7
Joined: Sat Oct 03, 2020 1:34 pm

#2 cylinder knock

Post by BlackSiR »

I got knock counts when I drive 5th gear, 6-8 knocks for 20 minutes with AEM SRI. When I bolted Invidia header to cat-back exhaustion on and went on one hour drive, the knock counts got worse, 22 knock counts in 30 minutes then I decided to run at 4,000 RPM and my knock count started to quiet down when I run 5th gear at 4,000 RPM and above, got one knock count for another 30 minutes because I'm keeping my engine above 4,000 RPM..

Only knock occurs when I am at 3,000 to 3,500 RPM in 5th and 6th gear. I datalogged, all knocks came from #2 cylinder and I googled, I see that almost everybody has that same problem, knock coming from #2 cylinder.

When I drive hard, revving high RPM, I don't get any knock count. Only occurs when I am cruising.

Has anyone solved that mystery knock, the #2 cylinder at 3,000-3,500 RPM in 5th and 6th gear? Do I need a better spark plugs or what? I just bought Denso M11S two weeks ago and I really don't want to drive around 4,500 RPM daily so I would like to know what is the cause of knocks at low RPM in 5th and 6th gear.

Denso M11S is a Life-Long spark plugs so do I need a better performance spark plugs?
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Spunkster
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Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: #2 cylinder knock

Post by Spunkster »

Have you tried reducing timing in the area it is registering knock?
BlackSiR
Posts: 7
Joined: Sat Oct 03, 2020 1:34 pm

Re: #2 cylinder knock

Post by BlackSiR »

I have not adjusted anything yet but radiator cooling fan.. I test drove it for last three days, hitting 80 MPH and I only got one knock on per test drive so it seems to get better now.. I have few theories.

1) I am thinking maybe new header/gasket was broken in and it acts smooth now, stop sending knock transfer to knock sensor?

2) It has been 30 temperature outside lately and I am running 180-190 temperature.. From what I remember, knocks occur when I am at 195 temperature so it could be heat soaking that causes weak ignition? It should get warmer tomorrow so I hope I will get to 195 temperature and sees what happen, I already set radiator cooling fan on at 193 and off at 185 because I am scared of knocks but I am not sure if it is the temperature that causes issues..

I am running 14-15 A/F ratio, is that a good thing?
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Spunkster
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Posts: 22741
Joined: Fri Sep 20, 2002 5:06 pm
Location: Hondata

Re: #2 cylinder knock

Post by Spunkster »

Cruising that should be ok, under full load (wot) it should be richer.
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