Knock Control Spiking Up

brandman537

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hey guys, I drive a 2017 Honda Civic Hatchback Sport 1.5T CVT. It has a Takeda Boxed intake, catless downpipe, and a ktuner v1.2 setup on a TSP Stage 1 Tune. I’ve recently gotten filled up with the wrong gas about 3 days ago and I know the tune requires (93 OCTANE), but I got filled up with 87 OCTANE by mistake. The knock control was going crazy, going to 0.60-0.70, knowing that it was on lower octane. I drove the car out, since I couldn’t take the gas out of the car, and burned the rest of the gas until I had 20 miles left on my range. I then yesterday filled up with 93 OCTANE fuel, and noticed the knock count go back down to 0.49. It has come to my attention that it spikes up and down from 0.49 to 0.52 Then then just falls back down to 0.49 as I step on the gas. When I do pulls it seems normal staying at 0.49, but should I be concerned when it spikes up go 0.52-0.55?

let me know please any advice can help and possible solutions. I attached a video below of the knock control going up to 0.55.
Thanks - Brandon

 

bbeem

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.55 is still really low and .49 is perfect. .6- .7 would be expected with 87 and is also fine. You're perfectly fine brother. Also like 50% throttle or about 2-4psi boost is the quickest way to reel it back to .49
 
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brandman537

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Hey thanks for the quick reply. So I know normal knock control is 0.49 which is good. But is it normal for knock to spike up randomly to 0.52 or 0.55? Then shoot back down to 0.49 smoothly ?
 

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It depends on a lot of factors, throttle input, rpm, boost... Mid rpm like 3k with just a little boost like 3psi will bring it back to .49 pretty quick. WOT might also raise it pretty quick. If you're just cruising lightly at 15% throttle it will probably just stay put and not raise or lower. .49 is the lowest possible. If it's higher it's not a problem but you can give it just a tiny bit of boost to reel it to .49 and it should more or less stay there unless you're really on it.
 
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brandman537

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yes, I’ve only noticed it go up too 0.52 when driving normally (not harsh on the gas) and when doing pulls it will go up when I go pass 5300 rpms which is normal. but I was just concerned for it going up from 0.49-0.52 when crusing, then going back down to 0.49 as I put the pedal down more.
 


bbeem

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Sounds right. .52 is still very low. Getting on it about half throttle should bring it down pretty quick like you see. I run 35% ethanol so mine is pretty well locked on .49 unless WOT 6k RPM. On tunerview you can set high and low limit colors so I set mine green under .55, grey from .56-.65 and red .66+. With my fuel and tune I rarely see it go red. Not that .66 is dangerous at all but Im probably beating it or have bad fuel if I see it go red.
 
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brandman537

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is running ethanol safe? Should I consider adding some to 93 or would it effect the way the car runs and hurt the motor?
 

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is running ethanol safe? Should I consider adding some to 93 or would it effect the way the car runs and hurt the motor?
If you have access to 93, use it. Tsp stage 1 is tuned for that. That should keep your knock locked at 0.49 unless it’s shitty 93.
 
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brandman537

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I usually go to a quick check and get 93, it always stays at 0.49 knock. But it sometimes fluctuates from 0.49-0.52. I don’t know what else there is.
 

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Ethanol can be up about 112oct. I'm in Iowa in our highest grade is 91oct no ethanol. Drive to Illinois and they don't have 91, they have 93 which is 91oct with 10% ethanol which brings it to 93.

More ethanol increases your octane which is good. The problem is ethanol is about 20% less energy dense. This means if you don't have a flex fuel sensor, your fuel trims will be off because your car is tuned for 0-10% and won't be adding the extra fuel needed. You'll be running lean. You need a FFC to measure the extra ethanol to inject the extra fuel.

If you're 93oct is already 10% ethanol just run that. If it's pure gas you can add a gallon of e85. You can monitor stft and ltft and afr in ktuner. A negative value is rich and positive is lean. If it's above like 5% you probably have too much ethanol. .52 is honestly really low so I wouldn't worry about that at all.
 


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brandman537

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appreciate the information? I’m pushing around 250 whp atm since the tune and all. But would the extra gallon of ethanol add any performance or added hp?
 

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appreciate the information? I’m pushing around 250 whp atm since the tune and all. But would the extra gallon of ethanol add any performance or added hp?
I would guess your 93 pump is 10% ethanol. If it is don't add any. If the pump says 93 0% ethanol you can add a gallon. The higher octane will reduce knock which will maintain maximum timing so you can make a couple extra HP at WOT. .52 is very low so don't even worry about that. If you do play around, monitor stft and ltft on your tunerview when driving. I would monitor that anyway...
 

 
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