LS2 goes rich at 5100rpm???

[Jarren_b]

I have now taken timing down and added a little fuel back in.

attached is the latest. What is better, a lean mixture and low timing? or higher timing and a rich mixture?

[schpenxel]

You'll get different answers on that one..

Here's an article that gives some background info on fuel vs. spark

http://www.innovatemotorsports.com/resources/rich.php

[Jarren_b]

Ive done more logs than i can even count at this point. Ive changed fuel and slight timing adjustments and cant get rid of the small amount of knock at various parts of the rpm. I know that my timing and furl isnt that far off because it was tuned on the dyno successfully. Im currently running a tr55 plug and am going to change to a tr6 to see if that solves my problem. When we tuned it, it was much cooler outside than it is now. I checked the IAT timing table to make sure it wasnt interfering and it doesnt seem to be.

Hopefully after colder plugs i can put the original timing back in and shoot for 12.6 afr

[schpenxel]

How much are you seeing? I've never gotten 100% rid of it on mine--just 1-2* every once in a while with no real reason behind it. I've started ignoring it.

[Jarren_b]

How much are you seeing? I've never gotten 100% rid of it on mine--just 1-2* every once in a while with no real reason behind it. I've started ignoring it.

Well dang. I was only seeing about 1-2 degrees. I saw 3 once. Ive now taken about 2 degrees out everywhere 1 degree in some spots. I even took timing out when I saw .5 knock. Am I too paranoid about it?
My AFR is about a 12.2-12.3 across the board. Any leaner and I saw knock.

Does my timing seem low to you guys?

The only thing I can think of is that maybe when it was tuned on the dyno the cylinder pressure was lower due to the fact that my vararam is worthless on the dyno. Im sure there is a lot more air in there at 120mph.
Im on 91 octane

Mods are PRC CNC'd ls3 heads Milled down to 66cc from 69.6

Ls7 cam, vararam, ls3 intake, ls7 exhaust.

Attached you will find my last log, Final tune, and my first tune that was done professionally for a comparison.

[Jarren_b]

Bump. Anyone?

[schpenxel]

Can you add dynamic airflow and VE airflow to the log?

Also, add knock learn factor

The knock in the first log would worry me a bit honestly.

Something I notice is your MAF airflow readings are jumping around pretty bad. Swinging about 10%. I think if you had a really fast wideband you would see AFR jumping around more too.

Have you ever tried it in SD only to see if it's any better?

[Jarren_b]

Check out this most recent log and tune. I did this just today. Ill add those to the log and post another. How do I put it in speed density only?

Take a look at this when you have a second!

http://www.hptuners.com/forum/showth...iving-me-crazy

Thanks for all your help!

[schpenxel]

The 0.5 to 1* little blips I totally ignore. Mine sometimes does it too.. always has and doesn't seem to matter what I do, it still does it.. so I ignore those

Over that I pay attention to though. I've always wondered if the < 1* blips are some sort of knock sensor learning routine the computer does. I have no real idea if that's what it is.. just something I've wondered about.

To go SD only you have to fail the MAF. Engine diag-->airflow, MAF frequency fail high to 1hz

[Jarren_b]

If i can just ignore those, i could add quite a bit more timing back in.. did that last log i posted look any better to you as far as the maf is concerned? Cant i just unplug the maf?

[schpenxel]

If you have a separate IAT, then yes.. if not, then no. ECM needs IAT reading to calculate air density when in SD mode

MAF reading was still jumping around some. It may be being smoothed out though, that's why I was interested in seeing how dynamic airflow looked

[Jarren_b]

Attached is a new log with the parameters you suggested. I rarely have seen any more than 2 degree's. Is it possible to barely desensitize the knock sensors? or not worth the risk? Does the PCM have to relearn knock every time I reflash?

[schpenxel]

Knock learn factor being at ~0.13 means it's somewhat biasing timing towards the low octane table. Basically high octane table value * 0.87 + low octane table value * 0.13 = timing used. Knock learn of 0 means only using high octane table, knock learn of 1 means only use low octane.. everything in between is somewhere between the two. So, it's reducing timing some for you already based on previous knock. Keep an eye on it and see if knock is worse when it's closer to 0. If so, I'd think it's probably real. If not, then quite possibly not. You'll hear (or read) some people say that after knock it "switches" to the low octane table.. this is hog wash. It biases between the two based on knock. It then slowly tries to go back towards the high octane table until it encounters knock again... in which case knock learn factor is increased again and the cycle repeats.

Dynamic airflow looks good and smooth so it looks like it's doing its job there. So don't worry about what I said about the MAF fluctuations earlier

You can desensitize the knock sensors a little bit if you want. I wouldn't do that just yet.. but I think I increased the cylinder threshold multipliers by a small amount on mine and it made a big difference. I can't remember exactly what I did at this point, it has been a while

[Jarren_b]

I think Ive gotten it where I want it. What I have attached seems to be the most timing and leanest AFR I can throw at it without knock. I did have to take a good amount out in some spots compared to my first tune that was done on the dyno but thats life I guess. For the most part it was 1 degree everywhere which im not too upset about. I hope I didnt kill my torque with all this but it doesnt feel too much different than I can really tell.

AFR is about a 12.3-6

Timing ranges from 23 down to 20-21 and then back up to 23. Im still learning timing curves but It seems like its best to have it higher, then lowest at peak torque and then ramp back up.. Is that the correct way to do it? I dont trust myself to hit a dyno yet but the bottom line Is I have probably flashed 30 tunes over the past few days trying to get as much timing back in as I could get and shoot for a 12.5 ish AFR. I guess Its just the heat and changes from being on dyno or in a more real world scenario on the street.

Take a look at my last log and tune and let me know what you guys think or if there is anything else I should do to potentially help my timing situation, I sincerely appreciate all the help. This is my first week of tuning and ive learned quite a bit thanks to all the help!

[schpenxel]

It's not unusual to sort of "bottom out" around wherever peak torque is.. then go back up a little after that. If it works it works.

Did I post that youtube video that explains knock/detonation? I can't remember if I showed it to you or not. If not I'll dig it back up