Phantom Knock on #2 cylinder?

FlashPro questions & answers specific to the 2006-2009 (US, UK, Asia) S2000
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fanboy_ray
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Phantom Knock on #2 cylinder?

Post by fanboy_ray » Wed Aug 31, 2011 2:45 pm

I've been searching around for quite some time and it seems (perhaps thankfully) that I am not the only one, but is cylinder 2 more prone to (phantom) knocking? I have logs that 99% of the knocks will be on #2.

I've seen a few people mention this phenomena (sometimes in passing when talking about other issues).

I thought perhaps this was something with the AEMV2 cal I was using, but it appears on stock as well, hot temperature, cold temperature, not doing anything crazy, just regular mundane driving.

Generally speaking, I see it at the end of the commute after getting off the freeway during city driving. It seems to be on low cam, during closed/open-cold (btw, how does open-cold compare to open-driving, it seems I can encounter them in my logs side by side at any tempurature)... I'm not sure what it is or if I should continue to worry about it.

Recently I did the 1.1.8.5 update, and it feels like I am seeing more knocks (on #2), which I didn't expect would have affected anything.

Has anyone else encountered this? (Have Hondata heard or experienced this type of behavior on S2000's?)

2006 AP2
AEM V2, T1R exhaust (regular dual with stock cat)
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Hondata
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Re: Phantom Knock on #2 cylinder?

Post by Hondata » Thu Sep 01, 2011 8:02 am

The knock sensor is closest to cylinder #2, and does seem to be more sensitive to knock on that cylinder. The easiest thing to do to see if something else in your engine is making noise is to reduce ignition in the area of knock and see if there is any change. 2-4 degrees should be enough. To find out where the knock is use a sensor overlay of the knock count. It it all columns 5-7 at 3100-3500 rpm.
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phantom_
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Re: Phantom Knock on #2 cylinder?

Post by phantom_ » Sat Sep 03, 2011 3:08 am

fanboy_ray wrote:I've been searching around for quite some time and it seems (perhaps thankfully) that I am not the only one, but is cylinder 2 more prone to (phantom) knocking? I have logs that 99% of the knocks will be on #2.

I've seen a few people mention this phenomena (sometimes in passing when talking about other issues).
I exactly have the same issue with you. I've tried plenty of things to get rid of cylinder #2 knock, however failed until now.
fanboy_ray wrote:I thought perhaps this was something with the AEMV2 cal I was using, but it appears on stock as well, hot temperature, cold temperature, not doing anything crazy, just regular mundane driving.
cylinder 2 knocks either modded (Simota CAI, BuddyClub testpipe and Invidia Q300 dual exhaust system) or stock (stock cat & stock exhaust).
fanboy_ray wrote:Generally speaking, I see it at the end of the commute after getting off the freeway during city driving. It seems to be on low cam, during closed/open-cold (btw, how does open-cold compare to open-driving, it seems I can encounter them in my logs side by side at any tempurature)... I'm not sure what it is or if I should continue to worry about it.
symptoms are the same, knock only occurs while cruising, between 50-80kPa intake vacuum and RPMS approximately 2900-5000. only on low cam, when i gently step on gas. no knocks on WOT or high cam.

i tried adding fuel to suspicious area at the low fuel table (50-80kPa 2900-5000RPM). it seems to lower the #2 knock; however the area in which the engine operating is closed-loop, so ECU slowly starts to trim the extra fuel (LTFT) and counteracts my fuel addition.

i tried increasing fuel only at cylinder 2 by adjusting individual cylinder trim. results are just the same as the above.
fanboy_ray wrote:Recently I did the 1.1.8.5 update, and it feels like I am seeing more knocks (on #2), which I didn't expect would have affected anything.
i did not notice any difference with the software version. i am also using 1.1.8.5.
fanboy_ray wrote:Has anyone else encountered this? (Have Hondata heard or experienced this type of behavior on S2000's?)
2006 Euro S

phantom_
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Re: Phantom Knock on #2 cylinder?

Post by phantom_ » Sat Sep 03, 2011 3:16 am

Hondata wrote:The knock sensor is closest to cylinder #2, and does seem to be more sensitive to knock on that cylinder. The easiest thing to do to see if something else in your engine is making noise is to reduce ignition in the area of knock and see if there is any change. 2-4 degrees should be enough. To find out where the knock is use a sensor overlay of the knock count. It it all columns 5-7 at 3100-3500 rpm.
i could not understand It it all columns 5-7 at 3100-3500 rpm ?

and i could not get your method of troubleshooting exactly: if we retard by 2-4 degrees and knock still exists, does that mean this is phantom knock?

we analyzed the knocking with several people, we can not hear any knock sound. even if the cyl#2 is prone to phantom knock, ECU increases knock control index, resulting in more retard in general. do you have any idea to cure this?
2006 Euro S

phantom_
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Re: Phantom Knock on #2 cylinder?

Post by phantom_ » Fri Sep 16, 2011 3:33 am

hondata, can you please clarify the above?
2006 Euro S

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Re: Phantom Knock on #2 cylinder?

Post by Hondata » Fri Sep 16, 2011 8:54 am

It it all columns 5-7 at 3100-3500 rpm
If you overlay the knock from the datalog on the tables, this is what you get. Of course, it could be a mechanical vibration from the same rpm and load combination, but the first step would be to retard timing a little in those 6 cells with knock, and see what happens.
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andrew87890
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Re: Phantom Knock on #2 cylinder?

Post by andrew87890 » Sun Dec 28, 2014 8:46 pm

i get this all the time i ignore it, im always getting 2-7 knock in the cylinder and none in the rest. (on the "tuned" map)

shind3
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Re: Phantom Knock on #2 cylinder?

Post by shind3 » Sat Apr 18, 2015 4:47 pm

symptoms are the same, knock only occurs while cruising, between 50-80kPa intake vacuum and RPMS approximately 2900-5000. only on low cam, when i gently step on gas. no knocks on WOT or high cam.
I'm seeing a similar thing. between 55kpa and 85kpa and 3500 and 4100 RPM on Cylinder 2. I've removed as much as 6-7 degrees of timing in all 6 cells with no change to the point where it really bogs down due to reduced timing but still 'knocks'. No knock at all at WOT.

Everything is stock except 70mm TP.
New OEM motor mounts
New TCT
NGK PFR7G-11S at 0.041"

I tried to move the header heatshield and it seems to be securely mounted. O2 sensors are tight.

It's gotta be false knock, I just don't know what's causing it.

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Spunkster
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Re: Phantom Knock on #2 cylinder?

Post by Spunkster » Mon Apr 20, 2015 9:31 am

Have you tried adjusting the valves?

shind3
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Re: Phantom Knock on #2 cylinder?

Post by shind3 » Thu Apr 23, 2015 1:31 pm

I have. Maybe I screwed something up? I did it a few months before installing a FlashPro which was about 8K miles ago. The exhaust valves were within 9 to 12 thou but I adjusted them to 11. And the intake valve were pretty much all at 9 thou.

I guess I can take the valvetrain cover off and check again.

andrew87890
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Re: Phantom Knock on #2 cylinder?

Post by andrew87890 » Sat Aug 15, 2015 11:29 am

no matter what I do, I'm always getting phantom knock. ive retard the ignition so much and it still comes back.

I'm pretty sure its a bug in hondata software.

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Re: Phantom Knock on #2 cylinder?

Post by Hondata » Sun Aug 16, 2015 10:13 am

It is not a bug. If you retard ignition and the knock level does not change, then it is mechanical noise from the engine. The cause can be almost anything - aftermarket parts, a loose bolt etc. The most common causes are from after market valve train parts, exhaust headers and engine mounts.
However, if you're getting only 2-7 knock counts in 30 minutes or so, then I would not do anything.
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