Excessive kr

[hook]

I have an 08 Vette Coupe A6
ARH 1 7/8"
Corsa Sport
Super Bee M107 CAI
Vararam Power Wedge


I'm not sure if this is typical but I've pulled as much as 15 degrees in some cells dealing with KR. The car seems to be driving fine. It just wont quit popping up.

Another item that aught my attention was my LTFT Histogram. I dialed them in very close to 0, and repeatedly did short and long test runs to make sure they were solid and then after I enabled COT, PE and DFCO my averages are 5 and 6% some worse, WTF!

Maybe I need to crawl under there and make sure my headers aren't touching anything. I had to bend a little heat shield to make the ARH's fit.

I attached an excel spreadsheet with the difference between OEM Spark Adv and where it is now to reference.

[SultanHassanMasTuning]

make sure its actually knock, maybe burst knock. type of torque management

[hook]

I actually thought the same thing and disabled BK yesterday, but that's not what it is. I don't believe my KR Histogram is showing BK, could be wrong but from what I observed yesterday it isn't.

[Ranger6202]

skimmed through your scan. Noticed every time you had knock it was right after a lean condition. I noticed you run 18:1 quite often (if your WB is right). Your NB's are seeing it too as they're adding fuel in your trims. I checked your MAF curve/values since that's what you're strictly running, and some smoothing would help. When you tuned your MAF did you use your trims or WB?

[hook]

I used my MAF, but that was before I installed my WB. I think I'm going to start from scratch and just go off of the WB. Before I do that though Ill smooth out those areas some and see if it helps. I'm just kind of concerned now that I'm leaving HP on the table with that much timing pulled out.

[Ranger6202]

If you get your fueling right, you probably won't have to pull that timing. Lean will make you knock. If your WB was right, you need to add a lot of fuel in your 18:1 areas. In which case, the knock will probably go away and you'll keep your timing.

[hook]

I agree, thanks. I think your right the KR is being caused my lean conditions. I think its a result of me overshooting the VE table. I need to slow down and make gradual changes then smooth.

[Ranger6202]

Are you running the enhanced OS VE tables or using the Bluecat for the Gen IV Coefficient changes? I generally dial the maf in first with the gen iv's since its easier than the VVE crap if its not an enhanced OS. One word of caution on the WB tuning compared to the Fuel Trim tuning. If your WB's read slightly differently than your NB's, you will always see that error when put everything back for closed loop. Previously i used my WB for tuning my part throttle and idle, but got tired of chasing my tail as i would always have error one way or the other and sometimes real bad. Now that i use trims....i can tune PT and Idle in half the time it took me with the WB's. Of course though WB is a must for WOT.

[10_SS]

What's wrong with the log I downloaded? It shows no real knock.. only a few spots with like 0.3degrees of knock. Also one example of a lean spot on the WB at Frame 11302 but it's only showing max lean of 14.0AFR when the commanded is 12.99. I still see no knock here. I do see Burst knock right when you hit the throttle but that's normal.

The only time I see 18AFR is when your cruising, and that's normal as the fuel mixture swings back and forth from rich to lean... that's how stock 02's sense if it's rich or lean by switching back and forth across 14.67... your WB picks that up also but under normal cruising (closed loop, not PE mode) this is 100% normal. I do see some "Burst Knock" as the TPS is mashed, but this is also normal. Pic attached of what Im talking about...

But yes, it is lean during PE at a few frames, 11230, and others. One Frame# 36114, about 2300rpm-3000rpm, = 5500hz MAF (93kpa) - 5700hz MAF (91kpa).

So is my log not opening yours right? Or are you looking at the wrong things? Im pretty sure mine is right since small amounts of knock in other places looks compeltely normal... and your not able to reduce the knock because there's none to start with maybe?

For your reference, the only place there is real knock in the pic I showed is at these frames: 12018, 12481, and 12502. But this is very small (0.4-0.5degrees) and during cruise... normal!

My suggestion... get your knock seeing what Im seeing (which is nothing), leave the timing low... then get your fueling in line. Once your not that lean anymore, put timing back to stock then see how fueling is.

If you could take a snapshot of the knock your seeing with your "Table" also showing the knock, that'd be great cause in your table Im also not seeing it.

LEAN_NOKNOCK.PNG

[hook]

When I said "excessive KR" I meant repetitive. I've taken out as much as 15 degrees in some cells and every time i log I see more. Below is the Histogram I'm looking at for KR. There are a few others also.

Here is the strange thing. I've tuned and retuned the MAF from scratch probably 2 dozen time and I'm still seeing it. Yesterday I dialed them in on STFT only. The KR continues through the tune minimal though and picks right back up after I enable PE.

I'm starting to think it has something to do with my O2's. When I installed the headers and x-pipe they came with O2's from the seller who swore up and down they were new and off a same year vette. He also spliced them to reach. I've been looking closely at the sine waves and they seem a little slow. I think this is creating the lean and rich fuel trim swings even after I tuned the near 0. I went ahead and ordered the extensions and will install them this weekend and see if that helps.

I don't mind KR below 1 either and its not BK. Let me know what you think.



2014-08-28_21h54_26.jpg2014-08-28_21h55_32.jpg

[5FDP]

Why are you concerned with a minor blips of knock when you arent even getting on it???

They pose no threat to anything, it's just something that happens with any car really. Look at how long it lasts, MAYBE .5 to a full second and then it's completely gone. You couldnt tell anything happened it does it so quick.

You should be thankful you don't drive a gen 4 truck with a 5.3/6.2, they "knock" all the time while cruising or during weird throttle transitions.

[10_SS]

yea it looks like normal throttle transition knock... very small amounts, under high load and low rpm.... 100% normal. If you really want to see if it's real put some race gas in there see if it's gone 100%. You could also play with your burst knock to pull some timing during throttle transitions like that but it's not worth it. I get those small amounts especially at low RPM too. Lots of people do.

My wifes new 2013 direct injected Equinox knocks all the time... almost like they are advancing timing soo much and letting the knock system pull timing, to keep it right on the edge of max power.

[hook]

yea you guys are probably right. The more I research this the more common and unavoidable it looks. I'm going to throw in some racing gas and see what happens.

I just hate ignoring this stuff. Kind of drives me up the wall. What your saying makes sense, maybe that's why the KR Sensors are set so sensitive. I wish we knew more about this though because it seems to be very common.

[10_SS]

I posted some logs of a stock lS3 vette, earlier today on here someone wanted to see them.. Take a look you'll see tons of knock.

[Ranger6202]

my experience.....my '06 vmaxx....all of my burst knock is removed, and i'm running pretty high timing.....and i have no knock, nor have i messed with the knock sensitivity.
My friends '06 C6 with E-force and 3" pulley, had a little knock when we first started dialing in the fuel....since then....no knock, it is reduced timing and we haven't pushed it up yet, however, still NO knock. Both of us are only running 91 octane. He's pushing as much as 11#'s of boost. I do agree you could have false knock, but i disagree with those that say knock is normal on gen III trucks or any of the LS vehicles. The race gas should definitely tell you if its real knock, especially if your trims are still below the %5 and you're still seeing it or not.

[Ranger6202]

Went back through your scan, 10_SS is right, that knock is nothing to worry about, very minimal and not necessarily patterned to anything wrong per say. However when you are going lean, 18:1 and even a little more than that, you were in open loop still, tells me your MAF isn't calibrated in those areas....cause as soon as you o2's kick back on, it starts trimming and pulls it right back to stoich and adding around %10 fuel.
scan9.bmp

[10_SS]

Ranger I was going to say you must not have looked close at his log... but I think the area you showed in your pic is actually decel fuel cut? maybe?... RPM is steadily declining, TPS is bottomed out (not 0, but it never is on these cars), etc. Injector pulse doesn't go to 0 when fuel cut is active for some reason like the older cars does.

[Ranger6202]

10_SS you're right, i didn't look close enough. When i pulled the KR on the histogram it was definitely not worth worrying about. As for the frame i posted, alas you are right again. I added TPS and Vspeed to the trend so i didn't have to flip back and forth and it is definitely in a decel that it goes the leanest. However, now that i've looked a little more, yeah he needs to dial his maf in a little more. wberror2.jpg

[hook]

its mostly decal fuel cut and I think the rest is false and maybe some transient lean conditions. I'm going to put some racing gas in this week and see what happens. Ill have a look at those lean cells again and richen it up a tad. Thanks I didn't notice that.

[ingsteve]

Adjust fueling according to your stft (10-15 is very high) not with wideband. Calibrate again your wideband and use it only for wot. Then increase pe rate (your map was 85 but it didn't start richen to example 12.5afr so you experienced knock). Put back you timing values from stock map and repeat. 11degrees is too low in those areas.