Pretty simple question - how much KR is too much? is 1*, 3*, 5*? What if it's only for a very brief period?

Ideal would be 0 obviously, but what is the "safe" range?

I ask because I am getting KR at different, random RPM and boost levels in a series or pulls using the same tune. I retarded the timing across the board, added fuel, but still get very short segments of 1-4* knock retard, then it goes back to zero. An examle would be at 5psi I get 2* retard from 3200-3700 then it goes to zero up to 5800, the next pull it does it at 4500-5100 rpm, then again at 3500-4100. There is no easily defined pattern to it, and I don't want to pull so much timing and add so much fuel that I give up a bunch of power. The knock is not audible, but the sensor is picking it up

 

it could be false knock, are u getting tire spin when the knock shows up.
ar the engine mounts soft letting the engine rock when it tq's up letting a downpipe or something else rub or hit something.

is the ex mounted solidly, any heat shields under the car loose?

all these things + tons more can cause fake knock

i prefer not to use a knock sensor for these reasons, and just keep an eye on plugs for signs of detonation

 

Not sure on tire spin, probably as this thing spins like crazy right now, LCARBS are in the mail.

the engine is on solid mounts, exhaust is solid mounted to the SFC's, and hung once it's over the axle.

I can get to my drivers side plugs very easily, but the pass side takes a while, and the car has to be cool to get to them. The one side should be enough I suppose

I know I get some false knock on occasion from something, I'll have one data point that is like 6* or 10* KR at cruise, or idle randomly

 

with solid engine mounts i would think that getting a true reading from the sensor will be fairly hard

 

Untill you know if its false KR, any KR is not good IMO.

Ive been down that road of chasing down false KR and I know its no fun to find where its comeing from.

 

On high performance engines no knock is the only way to fly. On boosted engines knock is a quick death. Head gaskets if you're lucky, driving over the crankshaft if it isn't your day.

With everything being so tied together it is very possible that it is false knock. Only way to know is to check the spark plugs. Tiny black specks like pepper are signs of knock.

You can lower the knock sensor sensitivity by mounting it on a 45* street elbow. This is a plumbing piece that has male NPT on one end and female NPT on the other. Be sure to not over tighten the sensor. Spec is 11 to 14 ft/lbs of torque.

RBob.

 

Is this $58/$59 ?

I used to get tons of false knock on those masks.

You can't beat what RBob said. Check the plugs, and if needed desensitize the KS with an elbow.

-- Joe

 

thanks for the info fellas

I pulled all 4 drivers side plugs, zero sign of detonation I'll get pics up when i get a camera that will take a decent shot of the plugs

a bit carbon'd up since my tune is still fat, but no pepper, no aluminum,no pitting, cracks, etc.

 

could an LT4 knock sensor and filter be used?

 

all 4 drivers side plugs look like this, rich but no peppering at all

 

Idk may be just me but i see black specks and that plug looks like its been run lean. I could be wrong.

 

care to expand on where you see black spots?

I did a data log with 5000 samples, 3 Wot passes up to 6000rpm in 2nd/3rd and 3rd/4th, got some KR but its minimal and all between 3500 and 4500 (peak TQ range when it was NA). I have pulled 2* per PSI from my NA tune up, and am arounf 11.5-12 AFR when in bvoost (only 5psi).

I have attached the log file, and put just the KR rows on sheet two for easy viewing. The KR is RPM range isolated (3500-4500), and the knock count seems to jump up and initates KR one sample after the WG opens (changes from 99% to 55% duty cycle). I find it odd that the WG only triggers false knock at 3500 to 4500 rpm.

 

You could decrease the KR attack and increase the KR recovery rate on the $59. That helped me out when I was dealing with false KR. Although ever since I added in the new engine I had I have actually done the oppisite so that if theres any KR at all it takes timing out quicker and takes longer to recover. Im gun shy of KR as Im pretty certain thats what cracked my piston ring and broke a ring land in my last engine. I know this working on the attack and recovery rates doesnt desensitize the sensor at all, but its a good bandaid that may work for you as it did for me.

Have you tried to take out the amount of timing that its retarding and seeing if it, the KR, goes away???

Ive had to use a little hand held microscope to see the speckles sometimes but saw that they were there. Sometimes the speckles arent black at all and are more silverish since its basicaly metal particals.
But to be honest those plugs look ok. What sorts of AFR are you pulling on average. Looks like mid to upper 12's on that log? Mabey you could richen it up a tad. And aim for more like 12.0?? Just a though incase its actually real KR.

 

this is how mine is set up currently

yes, it seemed to go away in the next log, but then it came back again at the same values. I'm gonna pull like 5* in all boost cells and see if than takes it away i may just be on the edge and my last change was not quite enough. The thing is in that log it only actually pulls 1* or 1.5*, and only in 4 rows, the rest of the cells it shows KR are all recovery. That was my whole reason for this thread - ya know is that ok? is 4 KR events at only 1* enough to warrant pulling timing? I have spoken with numerous people who tune NA motors and when they see a bit of KR when its real hot out, or they are beating on the motor its OK, boost tends to have different rules though

The porcelain looks to be speck free of any sort, i scrutinized them pretty hard - but again FtrSpeedy if your seeing something im not let me know Id rather be wrong than melt a piston

my afr table is 14.2 @ 90kpa, 13.5 @ 100kpa, 12.6 @ 110kpa, 11.8 @120kpa, 11.5 @ 130 tp 15-kpa, and 11.0 @ 150+ kpa

I leaned out the 100 and 110kpa area since I make 1 to 3 psi at part throttle when accelrating lightly just cruising, it was killing my gas mileage. I guess that sounds more like a AE/PE issue huh?

 

The afr table is for closed loop fueling IIRC. I never ran closed loop, only open loop. Id rather tune it myself then let the ecm try to make up for my poor fueling tables.

Yea the AE/PE mode was a pita for me to get down too as it was way too much fueling in my case.

Happend to have a few gallons of race fuel?? That will tell you if its false KR or not...lol

Also keep in mind that if you start to take out so much timing that the car is super rich or is super rich from the AE then it will show false KR all day long and if you have the recovery down then it will take a while for it go away.

 

the afr table is just my target is is not used by the ECU in open loop. Its also used in autotune fwiw. i am past the autotune point with the tune, just tweaking now.

pulled 2 more degrees, added a bunch of fuel everywhere over 100kpa, beat on the car HARD today, 130 mile fun run cruising at 85+ the whole way, doing highway pulls in 3rd, 4thm and 5th the whole time. Only saw two cells with KR, one was 0.88* and was a one time event, the other was 18* and the whole row of data was all screwed up so it is not really knock.

I'm having another issue though, the AFR readings are not consistant, one day the tune will be right where I want it, then i let the car sit for a couple hours, and its back to rich everywhere. It is leaner when hot so im assuming all the temp based compensation tables are to blame. Has anyone had success with setting all the temp compensation tables to 1 or 0? just trying to simplify everything, i know thats not the idea way i just want to set everything to static conditions and change things as I get used to all the available features

 

autotune?? Your using tunerpro v4? Im on V5/6 so its all me, no autotune.

Not sure on your AFR problem but mines does go all over at times when its hot or changes to cold, but thats on the under 100kpa areas only. Boosted cells rarely change if its 50* out or 80* out.

 

yeah v4, I have issues data logging with v5 for whatever reason

and the afr inconsistency is only idle and up to 100kpa

 

I have the same inconsistant AFR problem from idle to 100kpa also. But mainly idle and 50Kpa and under is where i notice it the most. Its changes about 1.0 sometimes for no reason, but since its tuned for 14.5, I dont mind it changing i guess. Even though id really like to know why it does that.

 

I will see as low as 10:1 AFR, thats when the engine is not totally heat soaked. When its really good and hot, sometimes it will migrate to 13.5-14.8. After it gets to the good 13-14 range, if I shut if down, start it back up, it satays where I want it. Then I let the car cool, start it, heat it up and its back down to 11.5. No consistency.

 

wow. That alot more then what i see. I start it up and till its heat soaked its arround 12.5 Then after its heat soaked its where I want it 14.5 generaly. Have you ever had problems with the idleing hunting and surging when its heat soaked??

Sorry for over running the thread with other stuff.......

 

it bucks really bad in 1st when heat soaked, because its too lean

 

Ohh ok. No idle issues then. Have you ever played with the AE and PE

 

i mean it gets leaner in idle, but no issues with surging or dying. regardless of pe or ae, there has to be a compensation table somewhere based on temperature that changing fueling

 

And ideas on what F31 and F31m are under fueling??