1.5T Audible knock and stuttering at 2k rpm

[angerthosenear]

Vehicle:
2016 Civic EX-T 1.5T
All stock parts, K&N air filter, but still stock airbox.
Stock tune and Hondata +3/+6 makes no difference
97k miles
New spark plugs (NGK Laser Iridium)
Using premium fuel (93, USA)
First time running any tune (under 100 miles tuned)

Situation:
When driving (sitting in park and revving doesn't do this), and accelerating around 2000 rpm I'll occasionally get a notable stutter. Audible light pinging / knock can be heard. Car stutters a bit before continuing. If I give it more throttle before 2000 rpm it'll skip past this 2000 rpm bad zone and rev fine at 3k+ rpm. Notably has to have some load through the drivetrain. Since cruising at 2k rpm seems fine, it's just when accelerating at 2k rpm.

While yes I see lots of people say not to worry about knock count and look at knock control, the knock count here climbs from 0 to 10 on a random cylinder rapidly. Knock control goes from mid 50s to over 100 - 120+

After I get past this point and fiddle with the throttle everything is back to normal. The knock stops and the knock control eventually falls back down.

I've tried various pulls on stock tune, Hondata +3 tune, Hondata +6 tune. The tune used doesn't make a difference for when this occurs. It's easier to trigger the stutter when on any non-stock tune, and started after I first tried the +3 tune. While it does seem like the cause, even reverting to stock I still have the same issue. Could just be a coincidence due to age. Or some failure of a physical part after this. Maybe a failed mount and the powertrain is just clunking / heatshield? I know the knock sensors are just microphones, so I'm not sure if the heatshield banging around is just the right frequency for the knock sensor to trigger. Inspecting the engine bay however, everything seems fine.

It's a higher pitched pinging noise, and doesn't sound like rod knock since it doesn't do it when idle or revving in park. I'm not familiar with various knock noises specifically. And looking at YouTube videos about them is oddly difficult, but could be my search terms. Seems more like detonation / spark knock from what I can find though.

I have attached a couple data logs from Hondata logging. One from a shorter run with some knock, and another from a much longer drive. The ones with a 2 are the return trip. The main runs are with the Hondata +6 tune since it's the easiest to get this to trigger.

Posting this in the general thread since it also occurs on a stock tune.

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[RedCrabby]

based on your datalog fuel trim, your engine is running on lean side with ~ +5% strim AFM 3v and above, which is about 2K rpm region.

Running lean in long run is not good especially for a turbo charged engine. constantly running k.control above 100% is already a warning to you to do something about it.

Stock honda intake filter usually running on rich side with strim ~-5 to -15% and around -5% for AFM 3v and above. Did you ever tried switch back stock filter and see if situation improved ?

My personal experience, whenever I try to "fine tune" my rich strim near to 0%, lets say I move the region reading from -7% to -3%, I start to get knock count.
I have once try to "perfect" my strim to make it near 0% and what I get in exchange is more knocks especially in hot days.

Perhaps you can try make your engine runs richer and see if you still get knocks. Forget about the perfect 0% thing, make it runs average below -5% to -10% just to monitor if it helps on your knocking issue.

Bring up your AFM table, select all values under mass flow (g/s) row, select adjust by percentage and put -10 value.
This will bring your entire strim xy graph decrease by 10%.
Your highest reading is about +5%, this means the highest will be now -5% running richer.

You have to do something about your lean engine before something bad happen, hopefully it is not happening already.

Using premium fuel 93 octane with constant 100% k.control on stock tuning datalog is not good.
Did you ever try to change other gas station and see if it makes any difference ?

Healthy k.control should be ~54% and should not exceed 60%.

 

[angerthosenear]

based on your datalog fuel trim, your engine is running on lean side with ~ +5% strim AFM 3v and above, which is about 2K rpm region.

Running lean in long run is not good especially for a turbo charged engine. constantly running k.control above 100% is already a warning to you to do something about it.

Stock honda intake filter usually running on rich side with strim ~-5 to -15% and around -5% for AFM 3v and above.

My personal experience, whenever I try to "fine tune" my rich strim near to 0%, lets say I move the region reading from -7% to -3%, I start to get knock count.
I have once try to "perfect" my strim to make it near 0% and what I get in exchange is more knocks especially in hot days.

Perhaps you can try make your engine runs richer and see if you still get knocks. Forget about the perfect 0% thing, make it runs average below -5% to -10% just to monitor if it helps on your knocking issue.

Bring up your AFM table, select all values under mass flow (g/s) row, select adjust by percentage and put -10 value.
This will bring your entire strim xy graph decrease by 10%.
Your highest reading is about +5%, this means the highest will be now -5% running richer.

You have to do something about your lean engine before something bad happen, hopefully it is not happening already.

Using premium fuel 93 octane with constant 100% k.control on stock tuning datalog is not good.
Did you ever try to change other gas station and see if it makes any difference ?

Healthy k.control should be ~54% and should not exceed 60%.

Thanks for taking a look!

I originally was running 87 octane in this car it's whole life. And only recently swapped over to 93. I put two tanks of 93 through it before swapping to any tune. My local gas station has good traffic, but likely very little 93 octane use. I just filled up yesterday in a different town with much higher use and likely moderate 93 octane use. I'll know later today if that's all it is.

I did notice it was a bit lean when under load, but I wasn't sure if that's normal or not when accelerating like that. In light driving it wouldn't knock so hopefully there was no damage. It was just these runs where it would. Which somewhat reinforces the bad gas idea.

After a test drive on the new gas I'll try your AFM table suggestion and report back.

Edit: Meant to say 87 not 83.

 

[RedCrabby]

Thanks for taking a look!

I originally was running 83 octane in this car it's whole life. And only recently swapped over to 93. I put two tanks of 93 through it before swapping to any tune. My local gas station has good traffic, but likely very little 93 octane use. I just filled up yesterday in a different town with much higher use and likely moderate 93 octane use. I'll know later today if that's all it is.

I did notice it was a bit lean when under load, but I wasn't sure if that's normal or not when accelerating like that. In light driving it wouldn't knock so hopefully there was no damage. It was just these runs where it would. Which somewhat reinforces the bad gas idea.

After a test drive on the new gas I'll try your AFM table suggestion and report back.

I think for Civic, the min. fuel octane suppose to be 85 and above ? In my country the recommendation is RON92 which is equivalent to US 85 octane.
Maybe it is good idea to avoid 83, as I see your datalog, your engine retarded most of the time and definitely not good to have big number of knocks happening at the same time on the same cylinder....

For knock, there is always 3 factor which is the temp, pressure, and ign timing. the temperature can be help with the cooling from fuel mixture which turbo car prefer richer, which also will make the it harder to ignite and slower to expand its ignited pressure thus less power it produced.
However, I still prefer engine knock prevention in a balanced tuning. Just not worth to go into the lean path for just a little more power.

 

[Armin1989]

based on your datalog fuel trim, your engine is running on lean side with ~ +5% strim AFM 3v and above, which is about 2K rpm region.

Running lean in long run is not good especially for a turbo charged engine. constantly running k.control above 100% is already a warning to you to do something about it.

Stock honda intake filter usually running on rich side with strim ~-5 to -15% and around -5% for AFM 3v and above. Did you ever tried switch back stock filter and see if situation improved ?

My personal experience, whenever I try to "fine tune" my rich strim near to 0%, lets say I move the region reading from -7% to -3%, I start to get knock count.
I have once try to "perfect" my strim to make it near 0% and what I get in exchange is more knocks especially in hot days.

Perhaps you can try make your engine runs richer and see if you still get knocks. Forget about the perfect 0% thing, make it runs average below -5% to -10% just to monitor if it helps on your knocking issue.

Bring up your AFM table, select all values under mass flow (g/s) row, select adjust by percentage and put -10 value.
This will bring your entire strim xy graph decrease by 10%.
Your highest reading is about +5%, this means the highest will be now -5% running richer.

You have to do something about your lean engine before something bad happen, hopefully it is not happening already.

Using premium fuel 93 octane with constant 100% k.control on stock tuning datalog is not good.
Did you ever try to change other gas station and see if it makes any difference ?

Healthy k.control should be ~54% and should not exceed 60%.

From my experience, these cars do run rich on highway driving, and a but lean in city driving, mine does this, but my LTFT +1% and STFT is between -2 to +6% in city driving, and STFT is around -1 to -7% on highway driving, have you experience this? Or is yours running a bit rich even in city driving? Btw running a bit rich is better than lean

 

[angerthosenear]

I think for Civic, the min. fuel octane suppose to be 85 and above ? In my country the recommendation is RON92 which is equivalent to US 85 octane.
Maybe it is good idea to avoid 83, as I see your datalog, your engine retarded most of the time and definitely not good to have big number of knocks happening at the same time on the same cylinder....

For knock, there is always 3 factor which is the temp, pressure, and ign timing. the temperature can be help with the cooling from fuel mixture which turbo car prefer richer, which also will make the it harder to ignite and slower to expand its ignited pressure thus less power it produced.
However, I still prefer engine knock prevention in a balanced tuning. Just not worth to go into the lean path for just a little more power.

Whoops my bad. Certainly meant to say 87, 83 isn't even an option. Edited my post.

For these datalogs I had 93 in the tank.

Turns out everything does seem to be due to the bad gas I had. After changing gas all the knock went away. Knock control stayed around 55% and the AFR / S.Trim seem a lot more sane. I need to take a few more drives then I'll attach some datalogs.

What do you do in the case you do get bad gas? Some additives? Or something else.

 

[RedCrabby]

Whoops my bad. Certainly meant to say 87, 83 isn't even an option. Edited my post.

For these datalogs I had 93 in the tank.

Turns out everything does seem to be due to the bad gas I had. After changing gas all the knock went away. Knock control stayed around 55% and the AFR / S.Trim seem a lot more sane. I need to take a few more drives then I'll attach some datalogs.

What do you do in the case you do get bad gas? Some additives? Or something else.

Octane booster perhaps. I pumped min 91 octane most of the time. Experienced before a certain gas stations that give me poor quality even on the same octane. I would say the higher boost we went, the less tolerance our car on the gas quality.

Good thing is we will know which gas station has the highest quality in town!

 

[RedCrabby]

From my experience, these cars do run rich on highway driving, and a but lean in city driving, mine does this, but my LTFT +1% and STFT is between -2 to +6% in city driving, and STFT is around -1 to -7% on highway driving, have you experience this? Or is yours running a bit rich even in city driving? Btw running a bit rich is better than lean

Mine has "leaner" rich when in the highway, means it still below 0% around -3 to -5% , compare to -5% to -10% . I noticed with my +6/+9 base tune, it is not wise trying to adjust the fuel trim towards 0%, there you will have random knock happening. Sometime you get audible ping knock on 3k to 4k rpm and you feel the car stutter a bit which is bad.

The bad thing about running rich is you get more carbon deposit in long run, but that is always pros and cons.

 

[Armin1989]

Mine has "leaner" rich when in the highway, means it still below 0% around -3 to -5% , compare to -5% to -10% . I noticed with my +6/+9 base tune, it is not wise trying to adjust the fuel trim towards 0%, there you will have random knock happening. Sometime you get audible ping knock on 3k to 4k rpm and you feel the car stutter a bit which is bad.

The bad thing about running rich is you get more carbon deposit in long run, but that is always pros and cons.

The LTFT is what you should watch out for mostly in my opinion, my LTFT is at mostly between +2% to -1% which is really good, my stft bounce around +6% to around -2%

 

[RedCrabby]

The LTFT is what you should watch out for mostly in my opinion, my LTFT is at mostly between +2% to -1% which is really good, my stft bounce around +6% to around -2%

Not all region has LTFT. My region the LTFT is always -100%, means my ecu does not have this feature.

 

[Armin1989]

Not all region has LTFT. My region the LTFT is always -100%, means my ecu does not have this feature.

Wtf

 

[gtman]

He's right. Some ECU's don't report long term fuel trims. Crazy but true.

 

[RedCrabby]

I have seen many owners reported knock issue in Hondata forum, their fuel trim is always near or above 0%. I'm not sure for their case if they have adjusted the AFM or it is stock AFM values or aftermarket intake.

I have tried twice to confirm my case and yes the knocks increase and get more serious on higher RPM region whenever I move my negative STFT leaner and closer to 0%.

I decided to leave my AFM to "Stock" even it is showing like -5 to -10% off from 0% but hey I do not have any knock at all with a peace of mind.

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