Phantom Knock on #2 cylinder?

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

Post by fanboy_ray »

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 »

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_ »

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_ »

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
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Re: Phantom Knock on #2 cylinder?

Post by phantom_ »

hondata, can you please clarify the above?
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Hondata
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Re: Phantom Knock on #2 cylinder?

Post by Hondata »

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 »

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 »

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 »

Have you tried adjusting the valves?
shind3
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Re: Phantom Knock on #2 cylinder?

Post by shind3 »

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 »

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 »

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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futureal33
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Re: Phantom Knock on #2 cylinder?

Post by futureal33 »

Many years later, I am also getting the exact same problem.
Cylinder #2, only on columns 5-7 and all around 3500rpm area +/- 200rpm

I have experienced that my knock control increases so much that my timing was in single figures here and it is still reporting knock..

The master table commands around 27-33 degrees in this area, and over a journey where my knock control was up at 121%, my ignition timing values dipped as low as 11 degrees and it was still getting constant knock count in this area.

Screenshot attached.

I concluded that it must be "ghost knock" as surely it can't be knocking with just 11 degrees of timing when it should be 30+

Using premium 99RON fuel too.
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zanter
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Re: Phantom Knock on #2 cylinder?

Post by zanter »

Can someone tell me if my knocks are real or phantom and how to resolve my issue?

I drive a s2000 2007 JDM asian spec with test pipe. I suspect engine has been stroked to 2350cc cos I had to increase fueling around 10-15% from the original fueling low/high tables.

I understand that stroked ap2 run higher compression so I tried reducing the timing where the knock appears around 5.5-6k on high cam but I think its rather low already( around 24 degrees on high cam) so I increased fuel trim on cylinder 2(which knocks the most!) and reduce 2 degree timing on cylinder 2& 3 but to not much effect. I have tried to reduce the timing at knock area to 20 degrees but still knocks and will be down on power a lot!

The knocks occur on high acceleration as per attachment & data run concentrated on cylinder 2 (90%) and cylinder 3(10%)

Another thing is that I am forced to run closed loop on WOT( which is not ideal and runs like 14.5 afr) otherwise on Open loop the car will run super lean like 18-20 afr & run roughly / really down on power. despite increasing the fueling tables but doesnt help so I am forced to adjust the WOT fuel trims to force closed loop on high cam so at least the engine will run at 14.5 afr.( which is really too lean). But does running lean causes knocks?

The other possibility is cylinder 2 is coked up with too much carbon which means head job.

Thank you in advance for your help!
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EFICU
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Re: Phantom Knock on #2 cylinder?

Post by EFICU »

zanter wrote: Tue Jan 04, 2022 9:35 pm Can someone tell me if my knocks are real or phantom and how to resolve my issue?

I drive a s2000 2007 JDM asian spec with test pipe. I suspect engine has been stroked to 2350cc cos I had to increase fueling around 10-15% from the original fueling low/high tables.

I understand that stroked ap2 run higher compression so I tried reducing the timing where the knock appears around 5.5-6k on high cam but I think its rather low already( around 24 degrees on high cam) so I increased fuel trim on cylinder 2(which knocks the most!) and reduce 2 degree timing on cylinder 2& 3 but to not much effect. I have tried to reduce the timing at knock area to 20 degrees but still knocks and will be down on power a lot!

The knocks occur on high acceleration as per attachment & data run concentrated on cylinder 2 (90%) and cylinder 3(10%)

Another thing is that I am forced to run closed loop on WOT( which is not ideal and runs like 14.5 afr) otherwise on Open loop the car will run super lean like 18-20 afr & run roughly / really down on power. despite increasing the fueling tables but doesnt help so I am forced to adjust the WOT fuel trims to force closed loop on high cam so at least the engine will run at 14.5 afr.( which is really too lean). But does running lean causes knocks?

The other possibility is cylinder 2 is coked up with too much carbon which means head job.

Thank you in advance for your help!
A couple quick observations, you are most likely experiencing false knock. After working with Futureal33 for several months, his was prone to false knock and his original tuner adjusts the knock sensitivity tables from the start to not recognize or register knock. Apparently his original tuner works on a lot of euro spec S2000s and false knock is a major issue. Also, yes knock can occur from a lean condition. However, you are probably experiencing false knock.

Second, the car is not operating in closed loop for WOT in the datalog and calibration you're posting. Are these the ones you think are running in closed loop for WOT? This datalog is transitioning to open loop for WOT and the calibration is setup to do so.

To your main fueling issue, I believe your primary o2 sensor is failing under WOT conditions. If you look at how flat your AFR line is in the datalog, it's not really possible for the AFR line to be that flat when it's reading properly. In my experience, it only stays that flat when the primary o2 is failing. This would explain why you keep adding fuel and nothing happens, the sensor is not providing a proper reading to the ECU under WOT conditions. I have run into this on 8th gen Civic Si's now roughly fifteen times. When I look at Futureal33's datalog from me working with him, he is at 50% injector duty cycle at 5800 rpm, you are at 68% at 6800 rpm. You have roughly 20% more fuel in it than a euro spec car with similar mods and you're showing a lean AFR.

I would recommend you replace the primary oxygen sensor with a new unit, either OEM from Honda or and NGK or Denso unit. Then reinspect, but be prepared to get out of it on the WOT pull as it's likely extremely rich. Once you have a primary sensor that reads properly, it will give you a usable reading for AFR to tune from.

Once you have verified the new sensor is working, I would recommend you put all your cylinder trims you made back to OEM. You don't want cylinders trimming fuel and timing when you have another issue. Once you get a proper sensor in, you need to essentially start over and you will find the fuel tuning portion is very simple.

If you want more proof of the bad sensor, let me know and I can provide graphs for you showing the issue and remedies I mention in this post.
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